diff --git a/cmake/modules/AddPureSwift.cmake b/cmake/modules/AddPureSwift.cmake
index fc7ded0db64b5..ad177634dbca9 100644
--- a/cmake/modules/AddPureSwift.cmake
+++ b/cmake/modules/AddPureSwift.cmake
@@ -5,17 +5,16 @@ function(force_target_link_libraries TARGET)
   cmake_parse_arguments(ARGS "" "" "PUBLIC" ${ARGN})
 
   foreach(DEPENDENCY ${ARGS_PUBLIC})
-    target_link_libraries(${TARGET} PRIVATE
-      ${DEPENDENCY}
-    )
+    target_link_libraries(${TARGET} PRIVATE ${DEPENDENCY})
     add_dependencies(${TARGET} ${DEPENDENCY})
 
-    add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/forced-${DEPENDENCY}-dep.swift
-      COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_BINARY_DIR}/forced-${DEPENDENCY}-dep.swift
+    string(REGEX REPLACE [<>:\"/\\|?*] _ sanitized ${DEPENDENCY})
+    add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/forced-${sanitized}-dep.swift
+      COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_BINARY_DIR}/forced-${sanitized}-dep.swift
       DEPENDS ${DEPENDENCY}
       )
     target_sources(${TARGET} PRIVATE
-      ${CMAKE_CURRENT_BINARY_DIR}/forced-${DEPENDENCY}-dep.swift
+      ${CMAKE_CURRENT_BINARY_DIR}/forced-${sanitized}-dep.swift
     )
   endforeach()
 endfunction()
@@ -270,7 +269,8 @@ function(add_pure_swift_host_tool name)
 
   # Option handling
   set(options)
-  set(single_parameter_options)
+  set(single_parameter_options
+    SWIFT_COMPONENT)
   set(multiple_parameter_options
         DEPENDENCIES
         SWIFT_DEPENDENCIES)
@@ -324,6 +324,17 @@ function(add_pure_swift_host_tool name)
   target_include_directories(${name} PUBLIC
     ${SWIFT_HOST_LIBRARIES_DEST_DIR})
 
-  # Export this target.
-  set_property(GLOBAL APPEND PROPERTY SWIFT_EXPORTS ${name})
+  if(NOT APSHT_SWIFT_COMPONENT STREQUAL no_component)
+    add_dependencies(${APSHT_SWIFT_COMPONENT} ${name})
+    swift_install_in_component(TARGETS ${name}
+      COMPONENT ${APSHT_SWIFT_COMPONENT}
+      RUNTIME DESTINATION bin)
+    swift_is_installing_component(${APSHT_SWIFT_COMPONENT} is_installing)
+  endif()
+
+  if(NOT is_installing)
+    set_property(GLOBAL APPEND PROPERTY SWIFT_BUILDTREE_EXPORTS ${name})
+  else()
+    set_property(GLOBAL APPEND PROPERTY SWIFT_EXPORTS ${name})
+  endif()
 endfunction()
diff --git a/cmake/modules/AddSwift.cmake b/cmake/modules/AddSwift.cmake
index 328af19adc60d..35faa2ddb9adf 100644
--- a/cmake/modules/AddSwift.cmake
+++ b/cmake/modules/AddSwift.cmake
@@ -570,6 +570,9 @@ function(_add_swift_runtime_link_flags target relpath_to_lib_dir bootstrapping)
     else()
       message(FATAL_ERROR "Unknown BOOTSTRAPPING_MODE '${ASRLF_BOOTSTRAPPING_MODE}'")
     endif()
+  else()
+    target_link_directories(${target} PRIVATE
+      ${SWIFT_PATH_TO_SWIFT_SDK}/usr/lib/swift/${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}/${SWIFT_HOST_VARIANT_ARCH})
   endif()
 
   if(SWIFT_SWIFT_PARSER)
diff --git a/include/swift/AST/CASTBridging.h b/include/swift/AST/CASTBridging.h
index 4699a291a1fc2..e30951d490749 100644
--- a/include/swift/AST/CASTBridging.h
+++ b/include/swift/AST/CASTBridging.h
@@ -39,12 +39,9 @@
 
 SWIFT_BEGIN_NULLABILITY_ANNOTATIONS
 
-typedef long SwiftInt;
-typedef unsigned long SwiftUInt;
-
 typedef struct {
   const void *_Nullable data;
-  long numElements;
+  SwiftInt numElements;
 } BridgedArrayRef;
 
 typedef struct {
@@ -65,7 +62,7 @@ typedef struct {
   void *_Nullable TrailingCommaLoc;
 } BridgedTupleTypeElement;
 
-typedef enum ENUM_EXTENSIBILITY_ATTR(open) BridgedRequirementReprKind : long {
+typedef enum ENUM_EXTENSIBILITY_ATTR(open) BridgedRequirementReprKind : SwiftInt {
   /// A type bound T : P, where T is a type that depends on a generic
   /// parameter and P is some type that should bound T, either as a concrete
   /// supertype or a protocol to which T must conform.
@@ -92,7 +89,7 @@ typedef struct {
 } BridgedRequirementRepr;
 
 /// Diagnostic severity when reporting diagnostics.
-typedef enum ENUM_EXTENSIBILITY_ATTR(open) BridgedDiagnosticSeverity : long {
+typedef enum ENUM_EXTENSIBILITY_ATTR(open) BridgedDiagnosticSeverity : SwiftInt {
   BridgedFatalError,
   BridgedError,
   BridgedWarning,
@@ -102,7 +99,7 @@ typedef enum ENUM_EXTENSIBILITY_ATTR(open) BridgedDiagnosticSeverity : long {
 
 typedef void* BridgedDiagnostic;
 
-typedef enum ENUM_EXTENSIBILITY_ATTR(open) BridgedMacroDefinitionKind : long {
+typedef enum ENUM_EXTENSIBILITY_ATTR(open) BridgedMacroDefinitionKind : SwiftInt {
   /// An expanded macro.
   BridgedExpandedMacro = 0,
   /// An external macro, spelled with either the old spelling (Module.Type)
@@ -130,7 +127,7 @@ BridgedDiagnostic SwiftDiagnostic_create(void *diagnosticEngine,
                                          BridgedDiagnosticSeverity severity,
                                          const void *_Nullable sourceLoc,
                                          const unsigned char *_Nullable text,
-                                         long textLen);
+                                         SwiftInt textLen);
 
 /// Highlight a source range as part of the diagnostic.
 void SwiftDiagnostic_highlight(
@@ -141,14 +138,14 @@ void SwiftDiagnostic_fixItReplace(BridgedDiagnostic diag,
                                   const void *_Nullable replaceStartLoc,
                                   const void *_Nullable replaceEndLoc,
                                   const unsigned char *_Nullable newText,
-                                  long newTextLen);
+                                  SwiftInt newTextLen);
 
 /// Finish the given diagnostic and emit it.
 void SwiftDiagnostic_finish(BridgedDiagnostic diag);
 
 BridgedIdentifier
 SwiftASTContext_getIdentifier(void *ctx, const unsigned char *_Nullable str,
-                              long len);
+                              SwiftInt len);
 
 void *SwiftImportDecl_create(void *, void *, void *, char, void *,
                              BridgedArrayRef, BridgedArrayRef);
@@ -173,11 +170,11 @@ void *SwiftIdentifierExpr_create(void *ctx, BridgedIdentifier base, void *loc);
 
 void *SwiftStringLiteralExpr_create(void *ctx,
                                     const unsigned char *_Nullable string,
-                                    long len, void *TokenLoc);
+                                    SwiftInt len, void *TokenLoc);
 
 void *SwiftIntegerLiteralExpr_create(void *ctx,
                                      const unsigned char *_Nullable string,
-                                     long len, void *TokenLoc);
+                                     SwiftInt len, void *TokenLoc);
 
 void *SwiftBooleanLiteralExpr_create(void *ctx, _Bool value, void *TokenLoc);
 
@@ -194,7 +191,7 @@ void *SingleValueStmtExpr_createWithWrappedBranches(void *ctx, void *S,
 void *IfStmt_create(void *ctx, void *ifLoc, void *cond, void *_Nullable then,
                     void *_Nullable elseLoc, void *_Nullable elseStmt);
 
-typedef enum ENUM_EXTENSIBILITY_ATTR(open) ASTNodeKind : long {
+typedef enum ENUM_EXTENSIBILITY_ATTR(open) ASTNodeKind : SwiftInt {
   ASTNodeKindExpr,
   ASTNodeKindStmt,
   ASTNodeKindDecl
@@ -208,7 +205,7 @@ struct ASTNodeBridged {
 void *BraceStmt_create(void *ctx, void *lbloc, BridgedArrayRef elements,
                        void *rbloc);
 
-void *BridgedSourceLoc_advanced(void *loc, long len);
+void *BridgedSourceLoc_advanced(void *loc, SwiftInt len);
 
 void *ParamDecl_create(void *ctx, void *loc, void *_Nullable argLoc,
                        void *_Nullable argName, void *_Nullable paramLoc,
@@ -282,7 +279,7 @@ void *GenericParamList_create(void *ctx, void *lAngleLoc,
                               BridgedArrayRef reqs, void *rAngleLoc);
 void *GenericTypeParamDecl_create(void *ctx, void *declContext,
                                   BridgedIdentifier name, void *nameLoc,
-                                  void *_Nullable eachLoc, long index,
+                                  void *_Nullable eachLoc, SwiftInt index,
                                   _Bool isParameterPack);
 void GenericTypeParamDecl_setInheritedType(void *ctx, void *Param, void *ty);
 
diff --git a/include/swift/AST/PluginRegistry.h b/include/swift/AST/PluginRegistry.h
index e2f1fcb0f64a6..8ee553c8903c4 100644
--- a/include/swift/AST/PluginRegistry.h
+++ b/include/swift/AST/PluginRegistry.h
@@ -52,14 +52,13 @@ class LoadedExecutablePlugin {
 
   /// Represents the current process of the executable plugin.
   struct PluginProcess {
-    const llvm::sys::procid_t pid;
-    const int inputFileDescriptor;
-    const int outputFileDescriptor;
+    const llvm::sys::ProcessInfo process;
+    const int input;
+    const int output;
     bool isStale = false;
 
-    PluginProcess(llvm::sys::procid_t pid, int inputFileDescriptor,
-                  int outputFileDescriptor);
-
+    PluginProcess(llvm::sys::ProcessInfo process, int input, int output)
+        : process(process), input(input), output(output) {}
     ~PluginProcess();
 
     ssize_t write(const void *buf, size_t nbyte) const;
@@ -138,7 +137,8 @@ class LoadedExecutablePlugin {
     llvm::erase_value(onReconnect, fn);
   }
 
-  llvm::sys::procid_t getPid() { return Process->pid; }
+  llvm::sys::procid_t getPid() { return Process->process.Pid; }
+  llvm::sys::process_t getProcess() { return Process->process.Process; }
 
   NullTerminatedStringRef getExecutablePath() {
     return {ExecutablePath.c_str(), ExecutablePath.size()};
diff --git a/include/swift/Basic/CBasicBridging.h b/include/swift/Basic/CBasicBridging.h
index 86e7d5081d6dc..0835b111bee69 100644
--- a/include/swift/Basic/CBasicBridging.h
+++ b/include/swift/Basic/CBasicBridging.h
@@ -20,6 +20,69 @@
 // it causes importing the "Darwin"/"Glibc" overlay module. That violates
 // layering. i.e. Darwin overlay is created by Swift compiler.
 
+// NOTE: Partially ported from SwiftShim's SwiftStdint.h. We cannot include
+// that header here because it belongs to the runtime, but we need the same
+// logic for interoperability with Swift code in the compiler itself.
+// stdint.h is provided by Clang, but it dispatches to libc's stdint.h.  As a
+// result, using stdint.h here would pull in Darwin module (which includes
+// libc). This creates a dependency cycle, so we can't use stdint.h in
+// SwiftShims.
+// On Linux, the story is different. We get the error message
+// "/usr/include/x86_64-linux-gnu/sys/types.h:146:10: error: 'stddef.h' file not
+// found"
+// This is a known Clang/Ubuntu bug.
+
+// Clang has been defining __INTxx_TYPE__ macros for a long time.
+// __UINTxx_TYPE__ are defined only since Clang 3.5.
+#if defined(_MSC_VER) && !defined(__clang__)
+typedef __int64 __swiftc_int64_t;
+typedef unsigned __int64 __swiftc_uint64_t;
+typedef int __swiftc_int32_t;
+typedef unsigned int __swiftc_uint32_t;
+#elif !defined(__APPLE__) && !defined(__linux__) && !defined(__OpenBSD__) && !defined(__wasi__)
+#include <stdint.h>
+typedef int64_t __swiftc_int64_t;
+typedef uint64_t __swiftc_uint64_t;
+typedef int32_t __swiftc_int32_t;
+typedef uint32_t __swiftc_uint32_t;
+typedef intptr_t __swiftc_intptr_t;
+typedef uintptr_t __swiftc_uintptr_t;
+#else
+typedef __INT64_TYPE__ __swiftc_int64_t;
+#ifdef __UINT64_TYPE__
+typedef __UINT64_TYPE__ __swiftc_uint64_t;
+#else
+typedef unsigned __INT64_TYPE__ __swiftc_uint64_t;
+#endif
+
+typedef __INT32_TYPE__ __swiftc_int32_t;
+#ifdef __UINT32_TYPE__
+typedef __UINT32_TYPE__ __swiftc_uint32_t;
+#else
+typedef unsigned __INT32_TYPE__ __swiftc_uint32_t;
+#endif
+#endif
+
+#define __swiftc_join3(a,b,c) a ## b ## c
+
+#define __swiftc_intn_t(n) __swiftc_join3(__swiftc_int, n, _t)
+#define __swiftc_uintn_t(n) __swiftc_join3(__swiftc_uint, n, _t)
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#if defined(_WIN64)
+typedef __swiftc_int64_t SwiftInt;
+typedef __swiftc_uint64_t SwiftUInt;
+#elif defined(_WIN32)
+typedef __swiftc_int32_t SwiftInt;
+typedef __swiftc_uint32_t SwiftUInt;
+#else
+#error unknown windows pointer width
+#endif
+#else
+typedef __swiftc_intn_t(__INTPTR_WIDTH__) SwiftInt;
+typedef __swiftc_uintn_t(__INTPTR_WIDTH__) SwiftUInt;
+#endif
+
 #if __clang__
 // Provide macros to temporarily suppress warning about the use of
 // _Nullable and _Nonnull.
@@ -48,7 +111,7 @@ extern "C" {
 
 typedef struct BridgedData {
   const char *_Nullable baseAddress;
-  unsigned long size;
+  SwiftUInt size;
 } BridgedData;
 
 void BridgedData_free(BridgedData data);
diff --git a/include/swift/Basic/Program.h b/include/swift/Basic/Program.h
index 0a4acffe23f82..6efa12b40773a 100644
--- a/include/swift/Basic/Program.h
+++ b/include/swift/Basic/Program.h
@@ -40,14 +40,12 @@ int ExecuteInPlace(const char *Program, const char **args,
                    const char **env = nullptr);
 
 struct ChildProcessInfo {
-  llvm::sys::procid_t Pid;
-  int WriteFileDescriptor;
-  int ReadFileDescriptor;
+  llvm::sys::ProcessInfo ProcessInfo;
+  int Write;
+  int Read;
 
-  ChildProcessInfo(llvm::sys::procid_t Pid, int WriteFileDescriptor,
-                   int ReadFileDescriptor)
-      : Pid(Pid), WriteFileDescriptor(WriteFileDescriptor),
-        ReadFileDescriptor(ReadFileDescriptor) {}
+  ChildProcessInfo(llvm::sys::ProcessInfo ProcessInfo, int Write, int Read)
+      : ProcessInfo(ProcessInfo), Write(Write), Read(Read) {}
 };
 
 /// This function executes the program using the argument provided.
diff --git a/include/swift/Driver/ToolChain.h b/include/swift/Driver/ToolChain.h
index b50c720ead1e3..5829dd543fd40 100644
--- a/include/swift/Driver/ToolChain.h
+++ b/include/swift/Driver/ToolChain.h
@@ -340,7 +340,10 @@ class ToolChain {
   void addLinkRuntimeLib(const llvm::opt::ArgList &Args,
                          llvm::opt::ArgStringList &Arguments,
                          StringRef LibName) const;
-    
+
+  virtual void addPluginArguments(const llvm::opt::ArgList &Args,
+                                  llvm::opt::ArgStringList &Arguments) const {}
+
   /// Validates arguments passed to the toolchain.
   ///
   /// An override point for platform-specific subclasses to customize the
diff --git a/lib/AST/CASTBridging.cpp b/lib/AST/CASTBridging.cpp
index 5b935d4cebb11..85a10183a0ac4 100644
--- a/lib/AST/CASTBridging.cpp
+++ b/lib/AST/CASTBridging.cpp
@@ -27,6 +27,8 @@ static SourceLoc getSourceLocFromPointer(const void *loc) {
 
 namespace {
   struct BridgedDiagnosticImpl {
+    typedef llvm::MallocAllocator Allocator;
+
     InFlightDiagnostic inFlight;
     std::vector<StringRef> textBlobs;
 
@@ -37,8 +39,10 @@ namespace {
 
     ~BridgedDiagnosticImpl() {
       inFlight.flush();
+
+      Allocator allocator;
       for (auto text: textBlobs) {
-        free((void*)text.data());
+        allocator.Deallocate(text.data(), text.size());
       }
     }
   };
@@ -48,11 +52,11 @@ BridgedDiagnostic SwiftDiagnostic_create(void *diagnosticEngine,
                                          BridgedDiagnosticSeverity severity,
                                          const void *sourceLocPtr,
                                          const unsigned char *textPtr,
-                                         long textLen) {
+                                         SwiftInt textLen) {
   StringRef origText{
     reinterpret_cast<const char *>(textPtr), size_t(textLen)};
-  llvm::MallocAllocator mallocAlloc;
-  StringRef text = origText.copy(mallocAlloc);
+  BridgedDiagnosticImpl::Allocator alloc;
+  StringRef text = origText.copy(alloc);
 
   SourceLoc loc = getSourceLocFromPointer(sourceLocPtr);
 
@@ -95,15 +99,15 @@ void SwiftDiagnostic_fixItReplace(BridgedDiagnostic diagPtr,
                                   const void *replaceStartLocPtr,
                                   const void *replaceEndLocPtr,
                                   const unsigned char *newTextPtr,
-                                  long newTextLen) {
+                                  SwiftInt newTextLen) {
 
   SourceLoc startLoc = getSourceLocFromPointer(replaceStartLocPtr);
   SourceLoc endLoc = getSourceLocFromPointer(replaceEndLocPtr);
 
   StringRef origReplaceText{
     reinterpret_cast<const char *>(newTextPtr), size_t(newTextLen)};
-  llvm::MallocAllocator mallocAlloc;
-  StringRef replaceText = origReplaceText.copy(mallocAlloc);
+  BridgedDiagnosticImpl::Allocator alloc;
+  StringRef replaceText = origReplaceText.copy(alloc);
 
   BridgedDiagnosticImpl *impl = static_cast<BridgedDiagnosticImpl *>(diagPtr);
   impl->textBlobs.push_back(replaceText);
@@ -118,7 +122,7 @@ void SwiftDiagnostic_finish(BridgedDiagnostic diagPtr) {
 
 BridgedIdentifier
 SwiftASTContext_getIdentifier(void *ctx, const unsigned char *_Nullable str,
-                              long len) {
+                              SwiftInt len) {
   return const_cast<void *>(
       static_cast<ASTContext *>(ctx)
           ->getIdentifier(
@@ -145,7 +149,7 @@ void *SwiftImportDecl_create(void *ctx, void *dc, void *importLoc, char kind,
       getSourceLocFromPointer(kindLoc), std::move(importPath).get());
 }
 
-void *BridgedSourceLoc_advanced(void *loc, long len) {
+void *BridgedSourceLoc_advanced(void *loc, SwiftInt len) {
   SourceLoc l = getSourceLocFromPointer(loc).getAdvancedLoc(len);
   return const_cast<void *>(l.getOpaquePointerValue());
 }
@@ -216,7 +220,7 @@ void *SwiftIdentifierExpr_create(void *ctx, BridgedIdentifier base, void *loc) {
 
 void *SwiftStringLiteralExpr_create(void *ctx,
                                     const unsigned char *_Nullable string,
-                                    long len, void *TokenLoc) {
+                                    SwiftInt len, void *TokenLoc) {
   ASTContext &Context = *static_cast<ASTContext *>(ctx);
   auto stringRef = Context.AllocateCopy(
       StringRef{reinterpret_cast<const char *>(string), size_t(len)});
@@ -226,7 +230,7 @@ void *SwiftStringLiteralExpr_create(void *ctx,
 
 void *SwiftIntegerLiteralExpr_create(void *ctx,
                                      const unsigned char *_Nullable string,
-                                     long len, void *TokenLoc) {
+                                     SwiftInt len, void *TokenLoc) {
   ASTContext &Context = *static_cast<ASTContext *>(ctx);
   auto stringRef = Context.AllocateCopy(
       StringRef{reinterpret_cast<const char *>(string), size_t(len)});
@@ -582,7 +586,7 @@ void *GenericParamList_create(void *ctx, void *lAngleLoc,
 
 void *GenericTypeParamDecl_create(void *ctx, void *declContext,
                                   BridgedIdentifier name, void *nameLoc,
-                                  void *_Nullable eachLoc, long index,
+                                  void *_Nullable eachLoc, SwiftInt index,
                                   bool isParameterPack) {
   return GenericTypeParamDecl::createParsed(
       static_cast<DeclContext *>(declContext),
@@ -695,6 +699,6 @@ bool Plugin_waitForNextMessage(PluginHandle handle, BridgedData *out) {
   auto size = message.size();
   auto outPtr = malloc(size);
   memcpy(outPtr, message.data(), size);
-  *out = BridgedData{(const char *)outPtr, (unsigned long)size};
+  *out = BridgedData{(const char *)outPtr, (SwiftUInt)size};
   return false;
 }
diff --git a/lib/AST/PluginLoader.cpp b/lib/AST/PluginLoader.cpp
index 2f89336577107..3a78138fb766f 100644
--- a/lib/AST/PluginLoader.cpp
+++ b/lib/AST/PluginLoader.cpp
@@ -41,8 +41,13 @@ PluginRegistry *PluginLoader::getRegistry() {
 static StringRef pluginModuleNameStringFromPath(StringRef path) {
   // Plugin library must be named 'lib${module name}(.dylib|.so|.dll)'.
   // FIXME: Shared library prefix might be different between platforms.
+#if defined(_WIN32)
+  constexpr StringRef libPrefix{};
+  constexpr StringRef libSuffix = ".dll";
+#else
   constexpr StringRef libPrefix = "lib";
   constexpr StringRef libSuffix = LTDL_SHLIB_EXT;
+#endif
 
   StringRef filename = llvm::sys::path::filename(path);
   if (filename.starts_with(libPrefix) && filename.ends_with(libSuffix)) {
diff --git a/lib/AST/PluginRegistry.cpp b/lib/AST/PluginRegistry.cpp
index 25cdcf62d6fe5..beceff366b7d2 100644
--- a/lib/AST/PluginRegistry.cpp
+++ b/lib/AST/PluginRegistry.cpp
@@ -75,7 +75,9 @@ void *LoadedLibraryPlugin::getAddressOfSymbol(const char *symbolName) {
   auto &cached = resolvedSymbols[symbolName];
   if (cached)
     return cached;
-#if !defined(_WIN32)
+#if defined(_WIN32)
+  cached = GetProcAddress(static_cast<HMODULE>(handle), symbolName);
+#else
   cached = dlsym(handle, symbolName);
 #endif
   return cached;
@@ -153,9 +155,8 @@ llvm::Error LoadedExecutablePlugin::spawnIfNeeded() {
     return llvm::errorCodeToError(childInfo.getError());
   }
 
-  Process = std::make_unique<PluginProcess>(childInfo->Pid,
-                                            childInfo->ReadFileDescriptor,
-                                            childInfo->WriteFileDescriptor);
+  Process = std::make_unique<PluginProcess>(childInfo->ProcessInfo,
+                                            childInfo->Read, childInfo->Write);
 
   // Call "on reconnect" callbacks.
   for (auto *callback : onReconnect) {
@@ -165,15 +166,15 @@ llvm::Error LoadedExecutablePlugin::spawnIfNeeded() {
   return llvm::Error::success();
 }
 
-LoadedExecutablePlugin::PluginProcess::PluginProcess(llvm::sys::procid_t pid,
-                                                     int inputFileDescriptor,
-                                                     int outputFileDescriptor)
-    : pid(pid), inputFileDescriptor(inputFileDescriptor),
-      outputFileDescriptor(outputFileDescriptor) {}
-
 LoadedExecutablePlugin::PluginProcess::~PluginProcess() {
-  close(inputFileDescriptor);
-  close(outputFileDescriptor);
+#if defined(_WIN32)
+  _close(input);
+  _close(output);
+  CloseHandle(process.Process);
+#else
+  close(input);
+  close(output);
+#endif
 }
 
 LoadedExecutablePlugin::~LoadedExecutablePlugin() {
@@ -184,6 +185,17 @@ LoadedExecutablePlugin::~LoadedExecutablePlugin() {
 
 ssize_t LoadedExecutablePlugin::PluginProcess::read(void *buf,
                                                     size_t nbyte) const {
+#if defined(_WIN32)
+  size_t nread = 0;
+  while (nread < nbyte) {
+    int n = _read(input, static_cast<char*>(buf) + nread,
+                  std::min(static_cast<size_t>(UINT32_MAX), nbyte - nread));
+    if (n <= 0)
+      break;
+    nread += n;
+  }
+  return nread;
+#else
   ssize_t bytesToRead = nbyte;
   void *ptr = buf;
 
@@ -195,7 +207,7 @@ ssize_t LoadedExecutablePlugin::PluginProcess::read(void *buf,
 
   while (bytesToRead > 0) {
     ssize_t readingSize = std::min(ssize_t(INT32_MAX), bytesToRead);
-    ssize_t readSize = ::read(inputFileDescriptor, ptr, readingSize);
+    ssize_t readSize = ::read(input, ptr, readingSize);
     if (readSize <= 0) {
       // 0: EOF (the plugin exited?), -1: error (e.g. broken pipe.)
       // FIXME: Mark the plugin 'stale' and relaunch later.
@@ -206,10 +218,22 @@ ssize_t LoadedExecutablePlugin::PluginProcess::read(void *buf,
   }
 
   return nbyte - bytesToRead;
+#endif
 }
 
 ssize_t LoadedExecutablePlugin::PluginProcess::write(const void *buf,
                                                      size_t nbyte) const {
+#if defined(_WIN32)
+  size_t nwritten = 0;
+  while (nwritten < nbyte) {
+    int n = _write(output, static_cast<const char *>(buf) + nwritten,
+                   std::min(static_cast<size_t>(UINT32_MAX), nbyte - nwritten));
+    if (n <= 0)
+      break;
+    nwritten += n;
+  }
+  return nwritten;
+#else
   ssize_t bytesToWrite = nbyte;
   const void *ptr = buf;
 
@@ -221,7 +245,7 @@ ssize_t LoadedExecutablePlugin::PluginProcess::write(const void *buf,
 
   while (bytesToWrite > 0) {
     ssize_t writingSize = std::min(ssize_t(INT32_MAX), bytesToWrite);
-    ssize_t writtenSize = ::write(outputFileDescriptor, ptr, writingSize);
+    ssize_t writtenSize = ::write(output, ptr, writingSize);
     if (writtenSize <= 0) {
       // -1: error (e.g. broken pipe,)
       // FIXME: Mark the plugin 'stale' and relaunch later.
@@ -231,13 +255,14 @@ ssize_t LoadedExecutablePlugin::PluginProcess::write(const void *buf,
     bytesToWrite -= writtenSize;
   }
   return nbyte - bytesToWrite;
+#endif
 }
 
 llvm::Error LoadedExecutablePlugin::sendMessage(llvm::StringRef message) const {
   ssize_t writtenSize = 0;
 
   if (dumpMessaging) {
-    llvm::dbgs() << "->(plugin:" << Process->pid << ") " << message << "\n";
+    llvm::dbgs() << "->(plugin:" << Process->process.Pid << ") " << message << '\n';
   }
 
   const char *data = message.data();
@@ -297,7 +322,7 @@ llvm::Expected<std::string> LoadedExecutablePlugin::waitForNextMessage() const {
   }
 
   if (dumpMessaging) {
-    llvm::dbgs() << "<-(plugin:" << Process->pid << ") " << message << "\n";
+    llvm::dbgs() << "<-(plugin:" << Process->process.Pid << ") " << message << "\n";
   }
 
   return message;
diff --git a/lib/ASTGen/Sources/ASTGen/ASTGen.swift b/lib/ASTGen/Sources/ASTGen/ASTGen.swift
index 4aa3321190403..7a57715000942 100644
--- a/lib/ASTGen/Sources/ASTGen/ASTGen.swift
+++ b/lib/ASTGen/Sources/ASTGen/ASTGen.swift
@@ -1,11 +1,12 @@
 import CASTBridging
+import CBasicBridging
 import SwiftParser
 import SwiftSyntax
 
 extension Array {
   public func withBridgedArrayRef<T>(_ c: (BridgedArrayRef) -> T) -> T {
     withUnsafeBytes { buf in
-      c(BridgedArrayRef(data: buf.baseAddress!, numElements: count))
+      c(BridgedArrayRef(data: buf.baseAddress!, numElements: SwiftInt(count)))
     }
   }
 }
diff --git a/lib/ASTGen/Sources/ASTGen/Decls.swift b/lib/ASTGen/Sources/ASTGen/Decls.swift
index 815bb696b137b..6c725e5642ef0 100644
--- a/lib/ASTGen/Sources/ASTGen/Decls.swift
+++ b/lib/ASTGen/Sources/ASTGen/Decls.swift
@@ -1,4 +1,5 @@
 import CASTBridging
+import CBasicBridging
 import SwiftParser
 import SwiftSyntax
 
@@ -8,7 +9,7 @@ extension ASTGenVisitor {
     let equalLoc = self.base.advanced(by: node.initializer.equal.position.utf8Offset).raw
     var nameText = node.identifier.text
     let name = nameText.withUTF8 { buf in
-      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
     }
     let nameLoc = self.base.advanced(by: node.identifier.position.utf8Offset).raw
     let genericParams = node.genericParameterClause.map { self.visit($0).rawValue }
@@ -29,7 +30,7 @@ extension ASTGenVisitor {
     let loc = self.base.advanced(by: node.position.utf8Offset).raw
     var nameText = node.identifier.text
     let name = nameText.withUTF8 { buf in
-      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
     }
 
     let genericParams = node.genericParameterClause
@@ -52,7 +53,7 @@ extension ASTGenVisitor {
     let loc = self.base.advanced(by: node.position.utf8Offset).raw
     var nameText = node.identifier.text
     let name = nameText.withUTF8 { buf in
-      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
     }
 
     let out = ClassDecl_create(ctx, loc, name, loc, declContext)
@@ -95,7 +96,7 @@ extension ASTGenVisitor {
       // Swift AST represents "_" as nil.
       var text = nodeFirstName.text
       firstName = text.withUTF8 { buf in
-        SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+        SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
       }
     } else {
       firstName = nil
@@ -104,7 +105,7 @@ extension ASTGenVisitor {
     if let nodeSecondName = node.secondName {
       var text = nodeSecondName.text
       secondName = text.withUTF8 { buf in
-        SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+        SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
       }
     } else {
       secondName = nil
@@ -124,7 +125,7 @@ extension ASTGenVisitor {
 
     var nameText = node.identifier.text
     let name = nameText.withUTF8 { buf in
-      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
     }
 
     let returnType: ASTNode?
diff --git a/lib/ASTGen/Sources/ASTGen/Diagnostics.swift b/lib/ASTGen/Sources/ASTGen/Diagnostics.swift
index 7071029c43983..e0a41b819d7b4 100644
--- a/lib/ASTGen/Sources/ASTGen/Diagnostics.swift
+++ b/lib/ASTGen/Sources/ASTGen/Diagnostics.swift
@@ -1,4 +1,5 @@
 import CASTBridging
+import CBasicBridging
 import SwiftDiagnostics
 import SwiftSyntax
 
@@ -37,7 +38,7 @@ fileprivate func emitDiagnosticParts(
   let diag = mutableMessage.withUTF8 { messageBuffer in
     SwiftDiagnostic_create(
       diagEnginePtr, bridgedSeverity, sourceLoc(at: position),
-      messageBuffer.baseAddress, messageBuffer.count
+      messageBuffer.baseAddress, SwiftInt(messageBuffer.count)
     )
   }
 
@@ -76,7 +77,7 @@ fileprivate func emitDiagnosticParts(
     newText.withUTF8 { textBuffer in
       SwiftDiagnostic_fixItReplace(
         diag, replaceStartLoc, replaceEndLoc,
-        textBuffer.baseAddress, textBuffer.count
+        textBuffer.baseAddress, SwiftInt(textBuffer.count)
       )
     }
   }
@@ -149,7 +150,7 @@ extension SourceManager {
       SwiftDiagnostic_create(
         cxxDiagnosticEngine, bridgedSeverity,
         cxxSourceLocation(for: node, at: position),
-        messageBuffer.baseAddress, messageBuffer.count
+        messageBuffer.baseAddress, SwiftInt(messageBuffer.count)
       )
     }
 
@@ -202,7 +203,7 @@ extension SourceManager {
       newText.withUTF8 { textBuffer in
         SwiftDiagnostic_fixItReplace(
           diag, replaceStartLoc, replaceEndLoc,
-          textBuffer.baseAddress, textBuffer.count
+          textBuffer.baseAddress, SwiftInt(textBuffer.count)
         )
       }
     }
diff --git a/lib/ASTGen/Sources/ASTGen/Exprs.swift b/lib/ASTGen/Sources/ASTGen/Exprs.swift
index 38097c72cc218..b02ad452a37e6 100644
--- a/lib/ASTGen/Sources/ASTGen/Exprs.swift
+++ b/lib/ASTGen/Sources/ASTGen/Exprs.swift
@@ -1,4 +1,5 @@
 import CASTBridging
+import CBasicBridging
 import SwiftParser
 import SwiftSyntax
 
@@ -34,7 +35,7 @@ extension ASTGenVisitor {
 
     var text = node.identifier.text
     let id = text.withUTF8 { buf in
-      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
     }
 
     return .expr(SwiftIdentifierExpr_create(ctx, id, loc))
@@ -45,7 +46,7 @@ extension ASTGenVisitor {
 
     var text = node.identifier.text
     let id = text.withUTF8 { buf in
-      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
     }
 
     return .expr(SwiftIdentifierExpr_create(ctx, id, loc))
@@ -56,7 +57,7 @@ extension ASTGenVisitor {
     let base = visit(node.base!).rawValue
     var nameText = node.name.text
     let name = nameText.withUTF8 { buf in
-      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
     }
 
     return .expr(UnresolvedDotExpr_create(ctx, base, loc, name, loc))
@@ -78,7 +79,7 @@ extension ASTGenVisitor {
         return nil
       }
       return name.withUTF8 { buf in
-        SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+        SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
       }
     }
     let labelLocs: [UnsafeMutableRawPointer] = node.map {
diff --git a/lib/ASTGen/Sources/ASTGen/Generics.swift b/lib/ASTGen/Sources/ASTGen/Generics.swift
index 22163381143b0..4976560b85f91 100644
--- a/lib/ASTGen/Sources/ASTGen/Generics.swift
+++ b/lib/ASTGen/Sources/ASTGen/Generics.swift
@@ -1,4 +1,5 @@
 import CASTBridging
+import CBasicBridging
 import SwiftParser
 import SwiftSyntax
 
@@ -18,7 +19,7 @@ extension ASTGenVisitor {
   func visit(_ node: GenericParameterSyntax) -> ASTNode {
     var nodeName = node.name.text
     let name = nodeName.withUTF8 { buf in
-      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
     }
     let nameLoc = self.base.advanced(by: node.name.position.utf8Offset).raw
     let eachLoc = node.each.map { self.base.advanced(by: $0.position.utf8Offset).raw }
@@ -36,7 +37,7 @@ extension ASTGenVisitor {
 
     return .decl(
       GenericTypeParamDecl_create(
-        self.ctx, self.declContext, name, nameLoc, eachLoc, genericParameterIndex,
+        self.ctx, self.declContext, name, nameLoc, eachLoc, SwiftInt(genericParameterIndex),
         eachLoc != nil))
   }
 }
diff --git a/lib/ASTGen/Sources/ASTGen/Literals.swift b/lib/ASTGen/Sources/ASTGen/Literals.swift
index 1653d09ac348d..c80eedf8ee1a2 100644
--- a/lib/ASTGen/Sources/ASTGen/Literals.swift
+++ b/lib/ASTGen/Sources/ASTGen/Literals.swift
@@ -1,4 +1,5 @@
 import CASTBridging
+import CBasicBridging
 import SwiftParser
 import SwiftSyntax
 
@@ -8,7 +9,7 @@ extension ASTGenVisitor {
     var segment = node.segments.first!.as(StringSegmentSyntax.self)!.content.text
     return .expr(
       segment.withUTF8 { buf in
-        return SwiftStringLiteralExpr_create(ctx, buf.baseAddress, buf.count, loc)
+        return SwiftStringLiteralExpr_create(ctx, buf.baseAddress, SwiftInt(buf.count), loc)
       })
   }
 
@@ -17,7 +18,7 @@ extension ASTGenVisitor {
     var segment = node.digits.text
     return .expr(
       segment.withUTF8 { buf in
-        return SwiftIntegerLiteralExpr_create(ctx, buf.baseAddress, buf.count, loc)
+        return SwiftIntegerLiteralExpr_create(ctx, buf.baseAddress, SwiftInt(buf.count), loc)
       })
   }
 
diff --git a/lib/ASTGen/Sources/ASTGen/Macros.swift b/lib/ASTGen/Sources/ASTGen/Macros.swift
index 4ee025884bd42..4ead5f21ecc98 100644
--- a/lib/ASTGen/Sources/ASTGen/Macros.swift
+++ b/lib/ASTGen/Sources/ASTGen/Macros.swift
@@ -167,6 +167,11 @@ func allocateUTF8String(
   }
 }
 
+@_cdecl("swift_ASTGen_freeString")
+public func freeString(pointer: UnsafePointer<UInt8>?) {
+  pointer?.deallocate()
+}
+
 /// Diagnostics produced here.
 enum ASTGenMacroDiagnostic: DiagnosticMessage, FixItMessage {
   case thrownError(Error)
@@ -178,7 +183,11 @@ enum ASTGenMacroDiagnostic: DiagnosticMessage, FixItMessage {
   var message: String {
     switch self {
     case .thrownError(let error):
-      return String(describing: error)
+      if let err = error as? PluginError {
+        return err.description
+      } else {
+        return String(describing: error)
+      }
 
     case .oldStyleExternalMacro:
       return "external macro definitions are now written using #externalMacro"
@@ -278,7 +287,7 @@ func checkMacroDefinition(
       if module == "Builtin" {
         switch type {
         case "ExternalMacro":
-          return BridgedMacroDefinitionKind.builtinExternalMacro.rawValue
+          return Int(BridgedMacroDefinitionKind.builtinExternalMacro.rawValue)
 
         default:
           // Warn about the unknown builtin.
@@ -323,7 +332,7 @@ func checkMacroDefinition(
           ]
         )
       )
-      return BridgedMacroDefinitionKind.externalMacro.rawValue
+      return Int(BridgedMacroDefinitionKind.externalMacro.rawValue)
 
     case let .expansion(expansionSyntax, replacements: _)
         where expansionSyntax.macro.text == "externalMacro":
@@ -362,7 +371,7 @@ func checkMacroDefinition(
       // Form the "ModuleName.TypeName" result string.
       (externalMacroPointer.pointee, externalMacroLength.pointee) =
         allocateUTF8String("\(module).\(type)", nullTerminated: true)
-      return BridgedMacroDefinitionKind.externalMacro.rawValue
+      return Int(BridgedMacroDefinitionKind.externalMacro.rawValue)
 
     case let .expansion(expansionSyntax, replacements: replacements):
       // Provide the expansion syntax.
@@ -373,7 +382,7 @@ func checkMacroDefinition(
 
       // If there are no replacements, we're done.
       if replacements.isEmpty {
-        return BridgedMacroDefinitionKind.expandedMacro.rawValue
+        return Int(BridgedMacroDefinitionKind.expandedMacro.rawValue)
       }
 
       // The replacements are triples: (startOffset, endOffset, parameter index).
@@ -388,7 +397,7 @@ func checkMacroDefinition(
 
       replacementsPtr.pointee = replacementBuffer.baseAddress
       numReplacementsPtr.pointee = replacements.count
-      return BridgedMacroDefinitionKind.expandedMacro.rawValue
+      return Int(BridgedMacroDefinitionKind.expandedMacro.rawValue)
     }
   } catch let errDiags as DiagnosticsError {
     let srcMgr = SourceManager(cxxDiagnosticEngine: diagEnginePtr)
@@ -410,6 +419,14 @@ func checkMacroDefinition(
   }
 }
 
+@_cdecl("swift_ASTGen_freeExpansionReplacements")
+public func freeExpansionReplacements(
+  pointer: UnsafeMutablePointer<Int>?,
+  numReplacements: Int
+) {
+  UnsafeMutableBufferPointer(start: pointer, count: numReplacements).deallocate()
+}
+
 // Make an expansion result for '@_cdecl' function caller.
 func makeExpansionOutputResult(
   expandedSource: String?,
diff --git a/lib/ASTGen/Sources/ASTGen/Misc.swift b/lib/ASTGen/Sources/ASTGen/Misc.swift
index bb63fd0b1b181..422821744e6b1 100644
--- a/lib/ASTGen/Sources/ASTGen/Misc.swift
+++ b/lib/ASTGen/Sources/ASTGen/Misc.swift
@@ -1,4 +1,5 @@
 import CASTBridging
+import CBasicBridging
 import SwiftParser
 import SwiftSyntax
 
diff --git a/lib/ASTGen/Sources/ASTGen/PluginHost.swift b/lib/ASTGen/Sources/ASTGen/PluginHost.swift
index 33a87ca898eb2..7edb51aaf0854 100644
--- a/lib/ASTGen/Sources/ASTGen/PluginHost.swift
+++ b/lib/ASTGen/Sources/ASTGen/PluginHost.swift
@@ -121,7 +121,7 @@ struct CompilerPlugin {
 
   private func sendMessage(_ message: HostToPluginMessage) throws {
     let hadError = try LLVMJSON.encoding(message) { (data) -> Bool in
-      return Plugin_sendMessage(opaqueHandle, BridgedData(baseAddress: data.baseAddress, size: UInt(data.count)))
+      return Plugin_sendMessage(opaqueHandle, BridgedData(baseAddress: data.baseAddress, size: SwiftUInt(data.count)))
     }
     if hadError {
       throw PluginError.failedToSendMessage
@@ -277,7 +277,7 @@ class PluginDiagnosticsEngine {
       SwiftDiagnostic_create(
         cxxDiagnosticEngine, bridgedSeverity,
         cxxSourceLocation(at: position),
-        messageBuffer.baseAddress, messageBuffer.count)
+        messageBuffer.baseAddress, SwiftInt(messageBuffer.count))
     }
 
     // Emit highlights
@@ -296,7 +296,7 @@ class PluginDiagnosticsEngine {
       var newText = change.newText
       newText.withUTF8 { textBuffer in
         SwiftDiagnostic_fixItReplace(
-          diag, startLoc, endLoc, textBuffer.baseAddress, textBuffer.count)
+          diag, startLoc, endLoc, textBuffer.baseAddress, SwiftInt(textBuffer.count))
       }
     }
 
diff --git a/lib/ASTGen/Sources/ASTGen/SourceManager+MacroExpansionContext.swift b/lib/ASTGen/Sources/ASTGen/SourceManager+MacroExpansionContext.swift
index 9f74cb212aa62..b42fbc6186d7d 100644
--- a/lib/ASTGen/Sources/ASTGen/SourceManager+MacroExpansionContext.swift
+++ b/lib/ASTGen/Sources/ASTGen/SourceManager+MacroExpansionContext.swift
@@ -43,7 +43,13 @@ extension String {
   /// Retrieve the base name of a string that represents a path, removing the
   /// directory.
   var basename: String {
-    guard let lastSlash = lastIndex(of: "/") else {
+    guard let lastSlash = lastIndex(where: {
+#if os(iOS) || os(macOS) || os(tvOS) || os(watchOS) || os(Android) || os(Linux)
+        ["/"].contains($0)
+#else
+        ["/", "\\"].contains($0)
+#endif
+    }) else {
       return self
     }
 
diff --git a/lib/ASTGen/Sources/ASTGen/Types.swift b/lib/ASTGen/Sources/ASTGen/Types.swift
index eb2be48a8a89b..3bb73ef19d184 100644
--- a/lib/ASTGen/Sources/ASTGen/Types.swift
+++ b/lib/ASTGen/Sources/ASTGen/Types.swift
@@ -1,4 +1,5 @@
 import CASTBridging
+import CBasicBridging
 import SwiftParser
 import SwiftSyntax
 
@@ -8,7 +9,7 @@ extension ASTGenVisitor {
 
     var text = node.name.text
     let id = text.withUTF8 { buf in
-      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+      return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
     }
 
     guard let generics = node.genericArgumentClause else {
@@ -38,7 +39,7 @@ extension ASTGenVisitor {
 
       var nameText = nameToken.text
       let name = nameText.withUTF8 { buf in
-        return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+        return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
       }
       let nameLoc = self.base.advanced(by: nameToken.position.utf8Offset).raw
 
@@ -175,12 +176,12 @@ extension ASTGenVisitor {
     for element in elementList {
       var nameText = element.name?.text
       let name = nameText?.withUTF8 { buf in
-        return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+        return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
       }
       let nameLoc = element.name.map { self.base.advanced(by: $0.position.utf8Offset).raw }
       var secondNameText = element.secondName?.text
       let secondName = secondNameText?.withUTF8 { buf in
-        return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, buf.count)
+        return SwiftASTContext_getIdentifier(ctx, buf.baseAddress, SwiftInt(buf.count))
       }
       let secondNameLoc = element.secondName.map {
         self.base.advanced(by: $0.position.utf8Offset).raw
diff --git a/lib/ASTGen/Sources/LLVMJSON/LLVMJSON.swift b/lib/ASTGen/Sources/LLVMJSON/LLVMJSON.swift
index c0b98123881d9..1ab7a991c5e43 100644
--- a/lib/ASTGen/Sources/LLVMJSON/LLVMJSON.swift
+++ b/lib/ASTGen/Sources/LLVMJSON/LLVMJSON.swift
@@ -41,7 +41,7 @@ public struct LLVMJSON {
 
   /// Decode a JSON data to a Swift value.
   public static func decode<T: Decodable>(_ type: T.Type, from json: UnsafeBufferPointer<Int8>) throws -> T {
-    let data = BridgedData(baseAddress: json.baseAddress, size: UInt(json.count))
+    let data = BridgedData(baseAddress: json.baseAddress, size: SwiftUInt(json.count))
     let valuePtr = JSON_deserializedValue(data)
     defer { JSON_value_delete(valuePtr) }
 
diff --git a/lib/Basic/Program.cpp b/lib/Basic/Program.cpp
index 8c322f865a6fa..ac82fe52d4657 100644
--- a/lib/Basic/Program.cpp
+++ b/lib/Basic/Program.cpp
@@ -18,7 +18,11 @@
 #include "llvm/Config/config.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Program.h"
+#if defined(_WIN32)
+#include "llvm/Support/Windows/WindowsSupport.h"
+#endif
 
+#include <memory>
 #include <system_error>
 
 #if HAVE_POSIX_SPAWN
@@ -29,6 +33,12 @@
 #include <unistd.h>
 #endif
 
+#if defined(_WIN32)
+#define WIN32_LEAN_AND_MEAN
+#include <Windows.h>
+#include <io.h>
+#endif
+
 using namespace swift;
 
 int swift::ExecuteInPlace(const char *Program, const char **args,
@@ -175,7 +185,100 @@ swift::ExecuteWithPipe(llvm::StringRef program,
 #endif
   close(p1.read);
   close(p2.write);
-  return ChildProcessInfo(pid, p1.write, p2.read);
+  llvm::sys::ProcessInfo proc;
+  proc.Pid = pid;
+  return ChildProcessInfo(proc, p1.write, p2.read);
+}
+
+#elif defined(_WIN32)
+
+llvm::ErrorOr<swift::ChildProcessInfo>
+swift::ExecuteWithPipe(llvm::StringRef program,
+                       llvm::ArrayRef<llvm::StringRef> args,
+                       llvm::Optional<llvm::ArrayRef<llvm::StringRef>> env) {
+  using unique_handle = std::unique_ptr<void, decltype(&CloseHandle)>;
+  enum { PI_READ, PI_WRITE };
+
+  unique_handle input[2] = {
+    {INVALID_HANDLE_VALUE, CloseHandle},
+    {INVALID_HANDLE_VALUE, CloseHandle},
+  };
+  unique_handle output[2] = {
+    {INVALID_HANDLE_VALUE, CloseHandle},
+    {INVALID_HANDLE_VALUE, CloseHandle},
+  };
+  unique_handle error{INVALID_HANDLE_VALUE, CloseHandle};
+  HANDLE hRead = INVALID_HANDLE_VALUE, hWrite = INVALID_HANDLE_VALUE;
+  SECURITY_ATTRIBUTES saAttrs{sizeof(SECURITY_ATTRIBUTES), NULL, TRUE};
+
+  if (!CreatePipe(&hRead, &hWrite, &saAttrs, 0))
+    return std::error_code(GetLastError(), std::system_category());
+  output[PI_READ].reset(hRead);
+  output[PI_WRITE].reset(hWrite);
+
+  if (!SetHandleInformation(output[PI_READ].get(), HANDLE_FLAG_INHERIT, FALSE))
+    return std::error_code(GetLastError(), std::system_category());
+
+  if (!CreatePipe(&hRead, &hWrite, &saAttrs, 0))
+    return std::error_code(GetLastError(), std::system_category());
+  input[PI_READ].reset(hRead);
+  input[PI_WRITE].reset(hWrite);
+
+  if (!SetHandleInformation(input[PI_WRITE].get(), HANDLE_FLAG_INHERIT, FALSE))
+    return std::error_code(GetLastError(), std::system_category());
+
+  if (!DuplicateHandle(GetCurrentProcess(), GetStdHandle(STD_ERROR_HANDLE),
+                       GetCurrentProcess(), &hWrite, DUPLICATE_SAME_ACCESS,
+                       TRUE, DUPLICATE_SAME_ACCESS))
+    return std::error_code(GetLastError(), std::system_category());
+  error.reset(hWrite);
+
+  STARTUPINFO si = {0};
+  si.cb = sizeof(si);
+  si.hStdInput = input[PI_READ].get();
+  si.hStdOutput = output[PI_WRITE].get();
+  si.hStdError = error.get();
+  si.dwFlags = STARTF_USESTDHANDLES;
+
+  llvm::SmallVector<wchar_t, MAX_PATH> executable;
+  if (std::error_code ec = llvm::sys::windows::widenPath(program, executable))
+    return ec;
+
+  std::vector<StringRef> components;
+  components.push_back(program);
+  components.assign(args.begin(), args.end());
+  llvm::ErrorOr<std::wstring> commandline =
+      llvm::sys::flattenWindowsCommandLine(components);
+  if (!commandline)
+    return commandline.getError();
+
+  std::vector<wchar_t> command(commandline->size() + 1, 0);
+  std::copy(commandline->begin(), commandline->end(), command.begin());
+
+  PROCESS_INFORMATION pi = {0};
+  if (!CreateProcessW(executable.data(),
+                      command.data(), nullptr, nullptr, TRUE, 0, nullptr,
+                      nullptr, &si, &pi))
+    return std::error_code(GetLastError(), std::system_category());
+
+  unique_handle hThread{pi.hThread, CloseHandle};
+  unique_handle hProcess{pi.hProcess, CloseHandle};
+
+  int ifd = _open_osfhandle(reinterpret_cast<intptr_t>(input[PI_WRITE].get()), 0);
+  if (ifd < 0)
+    return std::error_code(errno, std::system_category());
+  input[PI_WRITE].release();
+
+  int ofd = _open_osfhandle(reinterpret_cast<intptr_t>(output[PI_READ].get()), 0);
+  if (ofd < 0) {
+    _close(ifd);
+    return std::error_code(errno, std::system_category());
+  }
+  output[PI_READ].release();
+
+  llvm::sys::ProcessInfo proc;
+  proc.Process = pi.hProcess;
+  return ChildProcessInfo(proc, ifd, ofd);
 }
 
 #else // HAVE_UNISTD_H
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 846d165345b56..7d61c18522a1c 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -43,12 +43,18 @@ if (SWIFT_SWIFT_PARSER)
 
   # Determine the SwiftSyntax shared library files that were built as
   # part of earlyswiftsyntax.
-  list(TRANSFORM SWIFT_SYNTAX_MODULES PREPEND ${CMAKE_SHARED_LIBRARY_PREFIX}
+  list(TRANSFORM SWIFT_SYNTAX_MODULES PREPEND "${CMAKE_SHARED_LIBRARY_PREFIX}"
        OUTPUT_VARIABLE SWIFT_SYNTAX_SHARED_LIBRARIES)
   list(TRANSFORM SWIFT_SYNTAX_SHARED_LIBRARIES APPEND
-       ${CMAKE_SHARED_LIBRARY_SUFFIX}
+       "${CMAKE_SHARED_LIBRARY_SUFFIX}"
        OUTPUT_VARIABLE SWIFT_SYNTAX_SHARED_LIBRARIES)
 
+  list(TRANSFORM SWIFT_SYNTAX_MODULES PREPEND "${CMAKE_IMPORT_LIBRARY_PREFIX}"
+    OUTPUT_VARIABLE SWIFT_SYNTAX_IMPORT_LIBRARIES)
+  list(TRANSFORM SWIFT_SYNTAX_IMPORT_LIBRARIES APPEND
+    "${CMAKE_IMPORT_LIBRARY_SUFFIX}" OUTPUT_VARIABLE
+    SWIFT_SYNTAX_IMPORT_LIBRARIES)
+
   # Interface library to collect swiftinterfaces and swiftmodules from
   # SwiftSyntax
   add_library(swiftSyntaxLibraries INTERFACE)
@@ -67,27 +73,47 @@ if (SWIFT_SWIFT_PARSER)
       )
     endif()
 
-    add_custom_command(
-      OUTPUT "${SWIFT_HOST_LIBRARIES_DEST_DIR}/${sharedlib}"
-      DEPENDS "${SWIFT_SYNTAX_LIBRARIES_BUILD_DIR}/${sharedlib}"
-      COMMAND ${CMAKE_COMMAND} -E copy_if_different ${SWIFT_SYNTAX_LIBRARIES_BUILD_DIR}/${sharedlib} ${SWIFT_HOST_LIBRARIES_DEST_DIR}/${sharedlib}
-      ${add_origin_rpath}
-    )
-
-    add_custom_target(copy_swiftSyntaxLibrary_${sharedlib}
-      DEPENDS "${SWIFT_HOST_LIBRARIES_DEST_DIR}/${sharedlib}"
-      COMMENT "Copying ${sharedlib}"
-    )
-
-    swift_install_in_component(
-      PROGRAMS "${SWIFT_HOST_LIBRARIES_DEST_DIR}/${sharedlib}"
-      DESTINATION "lib${LLVM_LIBDIR_SUFFIX}/swift/host"
-      COMPONENT compiler
-    )
+    if(CMAKE_SYSTEM_NAME MATCHES Windows)
+      add_custom_command(OUTPUT ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${sharedlib}
+                         DEPENDS "${SWIFT_PATH_TO_EARLYSWIFTSYNTAX_BUILD_DIR}/bin/${sharedlib}"
+                         COMMAND ${CMAKE_COMMAND} -E copy_if_different ${SWIFT_PATH_TO_EARLYSWIFTSYNTAX_BUILD_DIR}/bin/${sharedlib} ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${sharedlib})
+      add_custom_target(copy_swiftSyntaxLibrary_${sharedlib}
+                        DEPENDS ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${sharedlib}
+                        COMMENT "copying ${sharedlib}")
+      swift_install_in_component(PROGRAMS ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${sharedlib}
+                                 DESTINATION bin
+                                 COMPONENT compiler)
+    else()
+      add_custom_command(OUTPUT "${SWIFT_HOST_LIBRARIES_DEST_DIR}/${sharedlib}"
+                         DEPENDS "${SWIFT_SYNTAX_LIBRARIES_BUILD_DIR}/${sharedlib}"
+                         COMMAND ${CMAKE_COMMAND} -E copy_if_different ${SWIFT_SYNTAX_LIBRARIES_BUILD_DIR}/${sharedlib} ${SWIFT_HOST_LIBRARIES_DEST_DIR}/${sharedlib}
+                         ${add_origin_rpath})
+      add_custom_target(copy_swiftSyntaxLibrary_${sharedlib}
+                        DEPENDS "${SWIFT_HOST_LIBRARIES_DEST_DIR}/${sharedlib}"
+                        COMMENT "Copying ${sharedlib}")
+      swift_install_in_component(PROGRAMS "${SWIFT_HOST_LIBRARIES_DEST_DIR}/${sharedlib}"
+                                 DESTINATION "lib${LLVM_LIBDIR_SUFFIX}/swift/host"
+                                 COMPONENT compiler)
+    endif()
 
     add_dependencies(swiftSyntaxLibraries copy_swiftSyntaxLibrary_${sharedlib})
   endforeach()
 
+  if(CMAKE_SYSTEM_NAME MATCHES Windows)
+    foreach(implib ${SWIFT_SYNTAX_IMPORT_LIBRARIES})
+      add_custom_command(OUTPUT ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/swift/windows/${SWIFT_HOST_VARIANT_ARCH}/${implib}
+        DEPENDS ${SWIFT_PATH_TO_EARLYSWIFTSYNTAX_BUILD_DIR}/lib/swift/host/${implib}
+        COMMAND "${CMAKE_COMMAND}" -E copy_if_different ${SWIFT_PATH_TO_EARLYSWIFTSYNTAX_BUILD_DIR}/lib/swift/host/${implib} ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/swift/windows/${SWIFT_HOST_VARIANT_ARCH}/${implib})
+      add_custom_target(copy_swiftSyntaxLibrary_${implib}
+        DEPENDS ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/swift/windows/${SWIFT_HOST_VARIANT_ARCH}/${implib}
+        COMMENT "Copying ${implib}")
+      swift_install_in_component(PROGRAMS ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/swift/windows/${SWIFT_HOST_VARIANT_ARCH}/${implib}
+        DESTINATION lib
+        COMPONENT compiler)
+      add_dependencies(swiftSyntaxLibraries copy_swiftSyntaxLibrary_${implib})
+    endforeach()
+  endif()
+
   # Copy all of the Swift modules from earlyswiftsyntax so they can be found
   # in the same relative place within the build directory as in the final
   # toolchain.
diff --git a/lib/Driver/DarwinToolChains.cpp b/lib/Driver/DarwinToolChains.cpp
index a06f1cc77d0b0..9dc66f83a6ead 100644
--- a/lib/Driver/DarwinToolChains.cpp
+++ b/lib/Driver/DarwinToolChains.cpp
@@ -24,6 +24,7 @@
 #include "swift/Driver/Compilation.h"
 #include "swift/Driver/Driver.h"
 #include "swift/Driver/Job.h"
+#include "swift/IDETool/CompilerInvocation.h"
 #include "swift/Option/Options.h"
 #include "clang/Basic/DarwinSDKInfo.h"
 #include "clang/Basic/Version.h"
@@ -123,6 +124,31 @@ std::string toolchains::Darwin::sanitizerRuntimeLibName(StringRef Sanitizer,
       .str();
 }
 
+void
+toolchains::Darwin::addPluginArguments(const ArgList &Args,
+                                       ArgStringList &Arguments) const {
+  SmallString<64> pluginPath;
+  auto programPath = getDriver().getSwiftProgramPath();
+  CompilerInvocation::computeRuntimeResourcePathFromExecutablePath(
+      programPath, /*shared=*/true, pluginPath);
+
+  auto defaultPluginPath = pluginPath;
+  llvm::sys::path::append(defaultPluginPath, "host", "plugins");
+
+  // Default plugin path.
+  Arguments.push_back("-plugin-path");
+  Arguments.push_back(Args.MakeArgString(defaultPluginPath));
+
+  // Local plugin path.
+  llvm::sys::path::remove_filename(pluginPath); // Remove "swift"
+  llvm::sys::path::remove_filename(pluginPath); // Remove "lib"
+  llvm::sys::path::append(pluginPath, "local", "lib");
+  llvm::sys::path::append(pluginPath, "swift");
+  llvm::sys::path::append(pluginPath, "host", "plugins");
+  Arguments.push_back("-plugin-path");
+  Arguments.push_back(Args.MakeArgString(pluginPath));
+}
+
 static void addLinkRuntimeLibRPath(const ArgList &Args,
                                    ArgStringList &Arguments,
                                    StringRef DarwinLibName,
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index e232a46962a9c..a290cc5e1d27b 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -376,30 +376,8 @@ void ToolChain::addCommonFrontendArgs(const OutputInfo &OI,
   // options.
   inputArgs.AddAllArgs(arguments, options::OPT_plugin_search_Group);
   addPlatformSpecificPluginFrontendArgs(OI, output, inputArgs, arguments);
-  
-  // Toolchain-relative plugin paths
-  {
-    SmallString<64> pluginPath;
-    auto programPath = getDriver().getSwiftProgramPath();
-    CompilerInvocation::computeRuntimeResourcePathFromExecutablePath(
-        programPath, /*shared=*/true, pluginPath);
 
-    auto defaultPluginPath = pluginPath;
-    llvm::sys::path::append(defaultPluginPath, "host", "plugins");
-
-    // Default plugin path.
-    arguments.push_back("-plugin-path");
-    arguments.push_back(inputArgs.MakeArgString(defaultPluginPath));
-
-    // Local plugin path.
-    llvm::sys::path::remove_filename(pluginPath); // Remove "swift"
-    llvm::sys::path::remove_filename(pluginPath); // Remove "lib"
-    llvm::sys::path::append(pluginPath, "local", "lib");
-    llvm::sys::path::append(pluginPath, "swift");
-    llvm::sys::path::append(pluginPath, "host", "plugins");
-    arguments.push_back("-plugin-path");
-    arguments.push_back(inputArgs.MakeArgString(pluginPath));
-  }
+  addPluginArguments(inputArgs, arguments);
 
   // Pass through any subsystem flags.
   inputArgs.AddAllArgs(arguments, options::OPT_Xllvm);
diff --git a/lib/Driver/ToolChains.h b/lib/Driver/ToolChains.h
index c552d6b81246e..a7aab90990a1d 100644
--- a/lib/Driver/ToolChains.h
+++ b/lib/Driver/ToolChains.h
@@ -65,7 +65,10 @@ class LLVM_LIBRARY_VISIBILITY Darwin : public ToolChain {
                                      const JobContext &context) const override;
   InvocationInfo constructInvocation(const StaticLinkJobAction &job,
                                      const JobContext &context) const override;
-    
+
+  void addPluginArguments(const llvm::opt::ArgList &Args,
+                          llvm::opt::ArgStringList &Arguments) const override;
+
   void validateArguments(DiagnosticEngine &diags,
                          const llvm::opt::ArgList &args,
                          StringRef defaultTarget) const override;
@@ -113,8 +116,12 @@ class LLVM_LIBRARY_VISIBILITY Windows : public ToolChain {
 public:
   Windows(const Driver &D, const llvm::Triple &Triple) : ToolChain(D, Triple) {}
   ~Windows() = default;
+
   std::string sanitizerRuntimeLibName(StringRef Sanitizer,
                                       bool shared = true) const override;
+
+  void addPluginArguments(const llvm::opt::ArgList &Args,
+                          llvm::opt::ArgStringList &Arguments) const override;
 };
 
 class LLVM_LIBRARY_VISIBILITY WebAssembly : public ToolChain {
@@ -168,6 +175,9 @@ class LLVM_LIBRARY_VISIBILITY GenericUnix : public ToolChain {
   ~GenericUnix() = default;
   std::string sanitizerRuntimeLibName(StringRef Sanitizer,
                                       bool shared = true) const override;
+
+  void addPluginArguments(const llvm::opt::ArgList &Args,
+                          llvm::opt::ArgStringList &Arguments) const override;
 };
 
 class LLVM_LIBRARY_VISIBILITY Android : public GenericUnix {
diff --git a/lib/Driver/UnixToolChains.cpp b/lib/Driver/UnixToolChains.cpp
index 389afb821dd61..61498c144a28b 100644
--- a/lib/Driver/UnixToolChains.cpp
+++ b/lib/Driver/UnixToolChains.cpp
@@ -21,6 +21,7 @@
 #include "swift/Driver/Compilation.h"
 #include "swift/Driver/Driver.h"
 #include "swift/Driver/Job.h"
+#include "swift/IDETool/CompilerInvocation.h"
 #include "swift/Option/Options.h"
 #include "swift/Option/SanitizerOptions.h"
 #include "clang/Basic/Version.h"
@@ -47,6 +48,31 @@ toolchains::GenericUnix::sanitizerRuntimeLibName(StringRef Sanitizer,
       .str();
 }
 
+void
+toolchains::GenericUnix::addPluginArguments(const ArgList &Args,
+                                            ArgStringList &Arguments) const {
+  SmallString<64> pluginPath;
+  auto programPath = getDriver().getSwiftProgramPath();
+  CompilerInvocation::computeRuntimeResourcePathFromExecutablePath(
+      programPath, /*shared=*/true, pluginPath);
+
+  auto defaultPluginPath = pluginPath;
+  llvm::sys::path::append(defaultPluginPath, "host", "plugins");
+
+  // Default plugin path.
+  Arguments.push_back("-plugin-path");
+  Arguments.push_back(Args.MakeArgString(defaultPluginPath));
+
+  // Local plugin path.
+  llvm::sys::path::remove_filename(pluginPath); // Remove "swift"
+  llvm::sys::path::remove_filename(pluginPath); // Remove "lib"
+  llvm::sys::path::append(pluginPath, "local", "lib");
+  llvm::sys::path::append(pluginPath, "swift");
+  llvm::sys::path::append(pluginPath, "host", "plugins");
+  Arguments.push_back("-plugin-path");
+  Arguments.push_back(Args.MakeArgString(pluginPath));
+}
+
 ToolChain::InvocationInfo
 toolchains::GenericUnix::constructInvocation(const InterpretJobAction &job,
                                              const JobContext &context) const {
diff --git a/lib/Driver/WindowsToolChains.cpp b/lib/Driver/WindowsToolChains.cpp
index 5001fa33fd2a5..481daa7ba3640 100644
--- a/lib/Driver/WindowsToolChains.cpp
+++ b/lib/Driver/WindowsToolChains.cpp
@@ -44,6 +44,17 @@ std::string toolchains::Windows::sanitizerRuntimeLibName(StringRef Sanitizer,
       .str();
 }
 
+void
+toolchains::Windows::addPluginArguments(const ArgList &Args,
+                                        ArgStringList &Arguments) const {
+  SmallString<261> LibraryPath = StringRef(getDriver().getSwiftProgramPath());
+  llvm::sys::path::remove_filename(LibraryPath); // Remove `swift`
+
+  // Default plugin path.
+  Arguments.push_back("-plugin-path");
+  Arguments.push_back(Args.MakeArgString(LibraryPath));
+}
+
 ToolChain::InvocationInfo
 toolchains::Windows::constructInvocation(const DynamicLinkJobAction &job,
                                          const JobContext &context) const {
diff --git a/lib/Sema/TypeCheckMacros.cpp b/lib/Sema/TypeCheckMacros.cpp
index 07eeebbc10baf..385dac2818162 100644
--- a/lib/Sema/TypeCheckMacros.cpp
+++ b/lib/Sema/TypeCheckMacros.cpp
@@ -49,6 +49,8 @@ using namespace swift;
 extern "C" void *swift_ASTGen_resolveMacroType(const void *macroType);
 extern "C" void swift_ASTGen_destroyMacro(void *macro);
 
+extern "C" void swift_ASTGen_freeString(const char *str);
+
 extern "C" void *swift_ASTGen_resolveExecutableMacro(
     const char *moduleName, ptrdiff_t moduleNameLength,
     const char *typeName, ptrdiff_t typeNameLength,
@@ -64,6 +66,9 @@ extern "C" ptrdiff_t swift_ASTGen_checkMacroDefinition(
     ptrdiff_t **replacementsPtr,
     ptrdiff_t *numReplacements
 );
+extern "C" void swift_ASTGen_freeExpansionReplacements(
+    ptrdiff_t *replacementsPtr,
+    ptrdiff_t numReplacements);
 
 extern "C" ptrdiff_t swift_ASTGen_expandFreestandingMacro(
     void *diagEngine, void *macro, uint8_t externalKind,
@@ -197,8 +202,8 @@ MacroDefinition MacroDefinitionRequest::evaluate(
 
   // Clean up after the call.
   SWIFT_DEFER {
-    free(externalMacroNamePtr);
-    free(replacements);
+    swift_ASTGen_freeString(externalMacroNamePtr);
+    swift_ASTGen_freeExpansionReplacements(replacements, numReplacements);
   };
 
   if (checkResult < 0 && ctx.CompletionCallback) {
@@ -1054,7 +1059,7 @@ evaluateFreestandingMacro(FreestandingMacroExpansion *expansion,
     evaluatedSource = llvm::MemoryBuffer::getMemBufferCopy(
         {evaluatedSourceAddress, (size_t)evaluatedSourceLength},
         adjustMacroExpansionBufferName(*discriminator));
-    free((void *)evaluatedSourceAddress);
+    swift_ASTGen_freeString(evaluatedSourceAddress);
     break;
 #else
     ctx.Diags.diagnose(loc, diag::macro_unsupported);
@@ -1333,7 +1338,7 @@ static SourceFile *evaluateAttachedMacro(MacroDecl *macro, Decl *attachedTo,
     evaluatedSource = llvm::MemoryBuffer::getMemBufferCopy(
         {evaluatedSourceAddress, (size_t)evaluatedSourceLength},
         adjustMacroExpansionBufferName(*discriminator));
-    free((void *)evaluatedSourceAddress);
+    swift_ASTGen_freeString(evaluatedSourceAddress);
     break;
 #else
     attachedTo->diagnose(diag::macro_unsupported);
diff --git a/stdlib/public/SwiftShims/swift/shims/SwiftStdint.h b/stdlib/public/SwiftShims/swift/shims/SwiftStdint.h
index 7b83e90d72799..cd8d808cbd6a2 100644
--- a/stdlib/public/SwiftShims/swift/shims/SwiftStdint.h
+++ b/stdlib/public/SwiftShims/swift/shims/SwiftStdint.h
@@ -71,12 +71,12 @@ typedef unsigned __INT8_TYPE__ __swift_uint8_t;
 #define __swift_uintn_t(n) __swift_join3(__swift_uint, n, _t)
 
 #if defined(_MSC_VER) && !defined(__clang__)
-#if defined(_WIN32)
-typedef __swift_int32_t __swift_intptr_t;
-typedef __swift_uint32_t __swift_uintptr_t;
-#elif defined(_WIN64)
+#if defined(_WIN64)
 typedef __swift_int64_t __swift_intptr_t;
 typedef __swift_uint64_t __swift_uintptr_t;
+#elif defined(_WIN32)
+typedef __swift_int32_t __swift_intptr_t;
+typedef __swift_uint32_t __swift_uintptr_t;
 #else
 #error unknown windows pointer width
 #endif
diff --git a/stdlib/public/stubs/LibcShims.cpp b/stdlib/public/stubs/LibcShims.cpp
index 4c6e29e2a64b3..0350c515503bd 100644
--- a/stdlib/public/stubs/LibcShims.cpp
+++ b/stdlib/public/stubs/LibcShims.cpp
@@ -22,6 +22,7 @@
 #endif
 
 #include <stdio.h>
+#include <stdlib.h>
 
 #include "swift/shims/LibcShims.h"
 
diff --git a/test/ClangImporter/pch-bridging-header-deps-fine.swift b/test/ClangImporter/pch-bridging-header-deps-fine.swift
index 4f21828ba3d32..4dbb1fea1812c 100644
--- a/test/ClangImporter/pch-bridging-header-deps-fine.swift
+++ b/test/ClangImporter/pch-bridging-header-deps-fine.swift
@@ -1,30 +1,26 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: rm -f %t.*
-//
+
 // Generate a bridging PCH, use it in a swift file, and check that the swift file's .swiftdeps
 // mention the .h the PCH was generated from, and any .h files included in it.
-//
+
 // RUN: %target-swift-frontend -emit-pch -o %t.pch %/S/Inputs/chained-unit-test-bridging-header-to-pch.h
 // RUN: %target-swift-frontend -module-name test -c -emit-dependencies-path %t.d -emit-reference-dependencies-path %t.swiftdeps -primary-file %s -import-objc-header %t.pch
 // RUN: %FileCheck --check-prefix CHECK-DEPS %s < %t.d
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck --check-prefix CHECK-SWIFTDEPS --enable-yaml-compatibility %s < %t-processed.swiftdeps
 // RUN: %FileCheck --check-prefix CHECK-SWIFTDEPS2 --enable-yaml-compatibility %s < %t-processed.swiftdeps
 
 // RUN: %target-swift-frontend -module-name test -c -emit-dependencies-path %t.persistent.d -emit-reference-dependencies-path %t.persistent.swiftdeps -primary-file %s -import-objc-header %/S/Inputs/chained-unit-test-bridging-header-to-pch.h -pch-output-dir %t/pch
 // RUN: %FileCheck --check-prefix CHECK-DEPS %s < %t.persistent.d
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.persistent.swiftdeps %t-processed.persistent.swiftdeps
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.persistent.swiftdeps > %t-processed.persistent.swiftdeps
 // RUN: %FileCheck --check-prefix CHECK-SWIFTDEPS  --enable-yaml-compatibility %s < %t-processed.persistent.swiftdeps
 // RUN: %FileCheck --check-prefix CHECK-SWIFTDEPS2 --enable-yaml-compatibility %s < %t-processed.persistent.swiftdeps
 
 print(app_function(1))
 
-// CHECK-DEPS: pch-bridging-header-deps-fine.o : {{.*}}SOURCE_DIR{{/|\\}}test{{/|\\}}ClangImporter{{/|\\}}Inputs{{/|\\}}app-bridging-header-to-pch.h {{.*}}SOURCE_DIR{{/|\\}}test{{/|\\}}ClangImporter{{/|\\}}Inputs{{/|\\}}chained-unit-test-bridging-header-to-pch.h
+// CHECK-DEPS: pch-bridging-header-deps-fine.o : {{.*}}{{/|\\}}test{{/|\\}}ClangImporter{{/|\\}}Inputs{{/|\\}}app-bridging-header-to-pch.h {{.*}}{{/|\\}}test{{/|\\}}ClangImporter{{/|\\}}Inputs{{/|\\}}chained-unit-test-bridging-header-to-pch.h
 
-// CHECK-SWIFTDEPS: externalDepend {{.*}} 'SOURCE_DIR{{/|\\\\}}test{{/|\\\\}}ClangImporter{{/|\\\\}}Inputs{{/|\\\\}}app-bridging-header-to-pch.h'
-// CHECK-SWIFTDEPS: externalDepend {{.*}} 'SOURCE_DIR{{/|\\\\}}test{{/|\\\\}}ClangImporter{{/|\\\\}}Inputs{{/|\\\\}}chained-unit-test-bridging-header-to-pch.h'
+// CHECK-SWIFTDEPS: externalDepend {{.*}} '{{.*}}{{/|\\}}test{{/|\\}}ClangImporter{{/|\\}}Inputs{{/|\\}}app-bridging-header-to-pch.h'
+// CHECK-SWIFTDEPS: externalDepend {{.*}} '{{.*}}{{/|\\}}test{{/|\\}}ClangImporter{{/|\\}}Inputs{{/|\\}}chained-unit-test-bridging-header-to-pch.h'
 
 // CHECK-SWIFTDEPS2-NOT: {{.*}}.pch
diff --git a/test/Driver/windows-link-job.swift b/test/Driver/windows-link-job.swift
index eb2cb06891a73..78fe8873b0ac2 100644
--- a/test/Driver/windows-link-job.swift
+++ b/test/Driver/windows-link-job.swift
@@ -1,10 +1,11 @@
 // RUN: %empty-directory(%t/DISTINCTIVE-WINDOWS-PATH/usr/bin)
 // RUN: %empty-directory(%t/DISTINCTIVE-WINDOWS-PATH/usr/lib)
 // RUN: %hardlink-or-copy(from: %swift_frontend_plain, to: %t/DISTINCTIVE-WINDOWS-PATH/usr/bin/swiftc)
-// RUN: %host-library-env PATH= %t/DISTINCTIVE-WINDOWS-PATH/usr/bin/swiftc -target x86_64-unknown-windows-msvc -### -module-name link -emit-library %s 2>&1 | %FileCheck %s
+// RUN: env PATH= %t/DISTINCTIVE-WINDOWS-PATH/usr/bin/swiftc -target x86_64-unknown-windows-msvc -### -module-name link -emit-library %s 2>&1 | %FileCheck %s
 
 // swift-frontend cannot be copied to another location with bootstrapping because
 // it will not find the libswiftCore library with its relative RPATH.
 // UNSUPPORTED: swift_in_compiler
+// UNSUPPORTED: swift_swift_parser
 
 // CHECK: {{^}}clang
diff --git a/test/Frontend/dependencies-fine.swift b/test/Frontend/dependencies-fine.swift
index f7256e925cfb0..e540d1b59f5f2 100644
--- a/test/Frontend/dependencies-fine.swift
+++ b/test/Frontend/dependencies-fine.swift
@@ -1,17 +1,13 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %empty-directory(%t)
 
 // RUN: %target-swift-frontend -emit-dependencies-path - -resolve-imports "%S/../Inputs/empty file.swift" | %FileCheck -check-prefix=CHECK-BASIC %s
 // RUN: %target-swift-frontend -emit-reference-dependencies-path - -typecheck -primary-file "%S/../Inputs/empty file.swift" > %t.swiftdeps
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-BASIC-YAML %s <%t-processed.swiftdeps
 
 // RUN: %target-swift-frontend -emit-dependencies-path %t.d -emit-reference-dependencies-path %t.swiftdeps -typecheck -primary-file "%S/../Inputs/empty file.swift"
 // RUN: %FileCheck -check-prefix=CHECK-BASIC %s < %t.d
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-BASIC-YAML %s < %t-processed.swiftdeps
 
 // CHECK-BASIC-LABEL: - :
@@ -20,7 +16,7 @@
 // CHECK-BASIC-NOT: {{ }}:{{ }}
 
 // CHECK-BASIC-YAML-NOT: externalDepend {{.*}}empty
-// CHECK-BASIC-YAML: externalDepend {{.*}} '{{.*}}Swift.swiftmodule{{(/.+[.]swiftmodule)?}}'
+// CHECK-BASIC-YAML: externalDepend {{.*}} '{{.*}}Swift.swiftmodule{{/|\\}}{{(.+[.]swiftmodule)?}}'
 
 
 // RUN: %target-swift-frontend -emit-dependencies-path %t.d -emit-reference-dependencies-path %t.swiftdeps -typecheck "%S/../Inputs/empty file.swift" 2>&1 | %FileCheck -check-prefix=NO-PRIMARY-FILE %s
@@ -48,7 +44,7 @@
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-objc-interop -disable-objc-attr-requires-foundation-module -import-objc-header %S/Inputs/dependencies/extra-header.h -track-system-dependencies -emit-dependencies-path - -resolve-imports %s | %FileCheck -check-prefix=CHECK-IMPORT-TRACK-SYSTEM %s
 
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-objc-interop -disable-objc-attr-requires-foundation-module -import-objc-header %S/Inputs/dependencies/extra-header.h -emit-reference-dependencies-path %t.swiftdeps -typecheck -primary-file %s
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-IMPORT-YAML %s <%t-processed.swiftdeps
 
 // CHECK-IMPORT-LABEL: - :
@@ -87,14 +83,14 @@
 // CHECK-IMPORT-TRACK-SYSTEM-NOT: {{[^\\]}}:
 
 // CHECK-IMPORT-YAML-NOT: externalDepend {{.*}}dependencies-fine.swift
-// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}{{/|\\}}Swift.swiftmodule{{(/.+[.]swiftmodule)?}}'
+// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}{{/|\\}}Swift.swiftmodule{{/|\\}}{{(.+[.]swiftmodule)?}}'
 // CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}Inputs/dependencies/$$$$$.h'
-// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}Inputs/dependencies{{/|\\\\}}UserClangModule.h'
+// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}Inputs/dependencies{{/|\\}}UserClangModule.h'
 // CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}Inputs/dependencies/extra-header.h'
-// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}Inputs/dependencies{{/|\\\\}}module.modulemap'
-// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}{{/|\\\\}}ObjectiveC.swift'
-// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}{{/|\\\\}}Foundation.swift'
-// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}{{/|\\\\}}CoreGraphics.swift'
+// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}Inputs/dependencies{{/|\\}}module.modulemap'
+// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}{{/|\\}}ObjectiveC.swift'
+// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}{{/|\\}}Foundation.swift'
+// CHECK-IMPORT-YAML-DAG: externalDepend {{.*}} '{{.*}}{{/|\\}}CoreGraphics.swift'
 
 // CHECK-ERROR-YAML: # Dependencies are unknown because a compilation error occurred.
 
diff --git a/test/Frontend/dependencies-preservation-fine.swift b/test/Frontend/dependencies-preservation-fine.swift
index 4e2a29865a789..ab54154aeba37 100644
--- a/test/Frontend/dependencies-preservation-fine.swift
+++ b/test/Frontend/dependencies-preservation-fine.swift
@@ -1,7 +1,3 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // This test verifies that copies of dependency files are preserved after a
 // compilation. For example, if the first compilation produces 'foo.swiftdeps',
 // a second compilation should move 'foo.swiftdeps' to 'foo.swiftdeps~', then
@@ -11,7 +7,7 @@
 
 // First, produce the dependency files and verify their contents.
 // RUN: %target-swift-frontend -emit-reference-dependencies-path %t.swiftdeps -typecheck -primary-file "%S/../Inputs/empty file.swift"
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK %s < %t-processed.swiftdeps
 
 // CHECK-NOT: topLevel{{.*}}EmptyStruct{{.*}}true
@@ -22,7 +18,7 @@
 // file.
 // RUN: %target-swift-frontend -emit-reference-dependencies-path %t.swiftdeps -typecheck -primary-file %S/../Inputs/global_resilience.swift
 // RUN: %FileCheck -check-prefix=CHECK %s < %t.swiftdeps~
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-OVERWRITTEN %s < %t-processed.swiftdeps
 
 // CHECK-OVERWRITTEN:topLevel{{.*}}EmptyStruct{{.*}}true
diff --git a/test/IDE/complete_optionset.swift b/test/IDE/complete_optionset.swift
index 271e618324efd..fd3917c37e2d4 100644
--- a/test/IDE/complete_optionset.swift
+++ b/test/IDE/complete_optionset.swift
@@ -1,6 +1,7 @@
-// REQUIRES: swift_swift_parser
 // RUN: %empty-directory(%t)
-// RUN: %target-swift-ide-test -batch-code-completion -source-filename %s -filecheck %raw-FileCheck -completion-output-dir %t -plugin-path %swift-host-lib-dir/plugins
+// RUN: %target-swift-ide-test -batch-code-completion -source-filename %s -filecheck %raw-FileCheck -completion-output-dir %t -plugin-path %swift-plugin-dir
+
+// REQUIRES: swift_swift_parser
 
 @OptionSet<UInt8>
 struct ShippingOptions {
diff --git a/test/Incremental/Dependencies/function-fine.swift b/test/Incremental/Dependencies/function-fine.swift
index e72ab6f29cc53..42cf0b00f9f24 100644
--- a/test/Incremental/Dependencies/function-fine.swift
+++ b/test/Incremental/Dependencies/function-fine.swift
@@ -1,13 +1,9 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DOLD -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-OLD
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DNEW -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-NEW
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 private func testParamType(_: InterestingType) {}
diff --git a/test/Incremental/Dependencies/function-return-type-fine.swift b/test/Incremental/Dependencies/function-return-type-fine.swift
index f9ffb1d4f3c90..0852a9b06dc3a 100644
--- a/test/Incremental/Dependencies/function-return-type-fine.swift
+++ b/test/Incremental/Dependencies/function-return-type-fine.swift
@@ -1,13 +1,9 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DOLD -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-OLD
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DNEW -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-NEW
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 private func testReturnType() -> InterestingType { fatalError() }
diff --git a/test/Incremental/Dependencies/protocol-conformer-ext-fine.swift b/test/Incremental/Dependencies/protocol-conformer-ext-fine.swift
index 49330bda51a75..53b3ea9745d9e 100644
--- a/test/Incremental/Dependencies/protocol-conformer-ext-fine.swift
+++ b/test/Incremental/Dependencies/protocol-conformer-ext-fine.swift
@@ -1,13 +1,9 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DOLD -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-OLD
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DNEW -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-NEW
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 private struct Test {}
diff --git a/test/Incremental/Dependencies/protocol-conformer-fine.swift b/test/Incremental/Dependencies/protocol-conformer-fine.swift
index 9642793aee895..f73f340739dae 100644
--- a/test/Incremental/Dependencies/protocol-conformer-fine.swift
+++ b/test/Incremental/Dependencies/protocol-conformer-fine.swift
@@ -1,13 +1,9 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DOLD -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-OLD
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DNEW -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-NEW
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 private struct Test : InterestingProto {}
diff --git a/test/Incremental/Dependencies/reference-dependencies-dynamic-lookup-fine.swift b/test/Incremental/Dependencies/reference-dependencies-dynamic-lookup-fine.swift
index 3c0c74e79c9eb..2d24d68b8d1c1 100644
--- a/test/Incremental/Dependencies/reference-dependencies-dynamic-lookup-fine.swift
+++ b/test/Incremental/Dependencies/reference-dependencies-dynamic-lookup-fine.swift
@@ -1,15 +1,11 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %empty-directory(%t)
 // RUN: cp %s %t/main.swift
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -typecheck -primary-file %t/main.swift -emit-reference-dependencies-path - > %t.swiftdeps
 
 // Check that the output is deterministic.
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -typecheck -primary-file %t/main.swift -emit-reference-dependencies-path - > %t-2.swiftdeps
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t-2.swiftdeps %t-2-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t-2.swiftdeps > %t-2-processed.swiftdeps
 // RUN: diff %t-processed.swiftdeps %t-2-processed.swiftdeps
 
 // RUN: %FileCheck %s < %t-processed.swiftdeps
diff --git a/test/Incremental/Dependencies/reference-dependencies-fine.swift b/test/Incremental/Dependencies/reference-dependencies-fine.swift
index e2fba6628bf13..1081e31a7f309 100644
--- a/test/Incremental/Dependencies/reference-dependencies-fine.swift
+++ b/test/Incremental/Dependencies/reference-dependencies-fine.swift
@@ -1,7 +1,3 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %empty-directory(%t)
 // RUN: cp %s %t/main.swift
 
@@ -10,8 +6,8 @@
 // RUN: %target-swift-frontend -typecheck -primary-file %t/main.swift %S/../Inputs/reference-dependencies-helper.swift -emit-reference-dependencies-path - > %t-2.swiftdeps
 
 // Merge each entry onto one line and sort to overcome order differences
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t-2.swiftdeps %t-2-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t-2.swiftdeps > %t-2-processed.swiftdeps
 // RUN: diff %t-processed.swiftdeps %t-2-processed.swiftdeps
 
 // RUN: %FileCheck -check-prefix=NEGATIVE %s < %t-processed.swiftdeps
diff --git a/test/Incremental/Dependencies/reference-dependencies-members-fine.swift b/test/Incremental/Dependencies/reference-dependencies-members-fine.swift
index 0fec187e1d91d..bfe167373208d 100644
--- a/test/Incremental/Dependencies/reference-dependencies-members-fine.swift
+++ b/test/Incremental/Dependencies/reference-dependencies-members-fine.swift
@@ -1,15 +1,11 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %empty-directory(%t)
 // RUN: cp %s %t/main.swift
 
 // RUN: %target-swift-frontend -typecheck -primary-file %t/main.swift %S/../Inputs/reference-dependencies-members-helper.swift -emit-reference-dependencies-path - > %t.swiftdeps
 
 // RUN: %target-swift-frontend -typecheck -primary-file %t/main.swift %S/../Inputs/reference-dependencies-members-helper.swift -emit-reference-dependencies-path - > %t-2.swiftdeps
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t-2.swiftdeps %t-2-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t-2.swiftdeps > %t-2-processed.swiftdeps
 
 // RUN: diff %t-processed.swiftdeps %t-2-processed.swiftdeps
 
diff --git a/test/Incremental/Dependencies/struct-member-fine.swift b/test/Incremental/Dependencies/struct-member-fine.swift
index 629d5e4ed3b10..b723c68989f5e 100644
--- a/test/Incremental/Dependencies/struct-member-fine.swift
+++ b/test/Incremental/Dependencies/struct-member-fine.swift
@@ -1,13 +1,9 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DOLD -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-OLD
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DNEW -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-NEW
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 private struct Wrapper {
diff --git a/test/Incremental/Dependencies/subscript-fine.swift b/test/Incremental/Dependencies/subscript-fine.swift
index 8907034198080..994a4bd61cfe1 100644
--- a/test/Incremental/Dependencies/subscript-fine.swift
+++ b/test/Incremental/Dependencies/subscript-fine.swift
@@ -1,13 +1,9 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DOLD -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-OLD
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DNEW -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-NEW
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 struct Wrapper {
diff --git a/test/Incremental/Dependencies/typealias-fine.swift b/test/Incremental/Dependencies/typealias-fine.swift
index b9e27e265b69f..af140c8605b83 100644
--- a/test/Incremental/Dependencies/typealias-fine.swift
+++ b/test/Incremental/Dependencies/typealias-fine.swift
@@ -1,13 +1,9 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DOLD -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-OLD
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DNEW -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-NEW
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
 private struct Wrapper {
diff --git a/test/Incremental/Dependencies/var-fine.swift b/test/Incremental/Dependencies/var-fine.swift
index 89aafb9452132..90b1d75a83bd1 100644
--- a/test/Incremental/Dependencies/var-fine.swift
+++ b/test/Incremental/Dependencies/var-fine.swift
@@ -1,10 +1,6 @@
-// REQUIRES: shell
-// Also uses awk:
-// XFAIL OS=windows
-
 // RUN: %target-swift-frontend -emit-silgen -primary-file %s %S/Inputs/InterestingType.swift -DOLD -emit-reference-dependencies-path %t.swiftdeps -module-name main | %FileCheck %s -check-prefix=CHECK-OLD
 
-// RUN: %S/../../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t.swiftdeps %t-processed.swiftdeps
+// RUN: %{python} %S/../../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t.swiftdeps > %t-processed.swiftdeps
 
 // RUN: %FileCheck -check-prefix=CHECK-DEPS %s < %t-processed.swiftdeps
 
diff --git a/test/Inputs/process_fine_grained_swiftdeps.py b/test/Inputs/process_fine_grained_swiftdeps.py
new file mode 100644
index 0000000000000..5396d68c2aadb
--- /dev/null
+++ b/test/Inputs/process_fine_grained_swiftdeps.py
@@ -0,0 +1,36 @@
+
+import subprocess
+import sys
+
+# Fine-grained swiftdeps files use multiple lines for each graph node.
+# Compress such a file so that each entry is one line of the form:
+# <kind> <aspect> <context> <name> <isProvides>
+# Also sort for consistency, since the node order can vary.
+
+output = subprocess.run(
+    [
+        sys.argv[1],
+        "--to-yaml",
+        "--input-filename={}".format(sys.argv[2]),
+        "--output-filename=-",
+    ],
+    stdout=subprocess.PIPE,
+)
+entries = []
+k = a = c = n = s = p = ""
+for line in output.stdout.decode("utf-8").split("\n"):
+    if "kind:" in line:
+        k = line.split()[1]
+    if "aspect:" in line:
+        a = line.split()[1]
+    if "context:" in line:
+        c = line.split()[1]
+    if "name:" in line:
+        n = ' '.join(line.split()[1:])
+    if "sequenceNumber:" in line:
+        s = line.split()[1]
+    if "isProvides:" in line:
+        p = line.split()[1]
+        entries.append(' '.join([k, a, c, n, p]))
+entries.sort()
+print("\n".join(entries))
diff --git a/test/Inputs/process_fine_grained_swiftdeps.sh b/test/Inputs/process_fine_grained_swiftdeps.sh
deleted file mode 100755
index fb91c3875e95e..0000000000000
--- a/test/Inputs/process_fine_grained_swiftdeps.sh
+++ /dev/null
@@ -1,9 +0,0 @@
-#!/usr/bin/env sh
-# Fine-grained swiftdeps files use multiple lines for each graph node.
-# Compress such a file so that each entry is one line of the form:
-# <kind> <aspect> <context> <name> <isProvides>
-# Also sort for consistency, since the node order can vary.
-
-${1} --to-yaml --input-filename=${2} --output-filename=${3}.tmp
-
-awk '/kind:/ {k = $2}; /aspect:/ {a = $2}; /context:/ {c = $2}; /name/ {n = $2}; /sequenceNumber/ {s = $2}; /isProvides:/ {print k, a, c, n, $2}' < ${3}.tmp | sort > ${3}
\ No newline at end of file
diff --git a/test/Macros/lit.local.cfg b/test/Macros/lit.local.cfg
index 521ceea67705e..1ae3d3a80fb24 100644
--- a/test/Macros/lit.local.cfg
+++ b/test/Macros/lit.local.cfg
@@ -1,3 +1,30 @@
 # '-enable-experimental-feature Macros' requires an asserts build.
 if 'asserts' not in config.available_features:
     config.unsupported = True
+
+config.subsitutions = list(config.substitutions)
+
+def get_target_os():
+    import re
+    (run_cpu, run_vendor, run_os, run_version) = re.match('([^-]+)-([^-]+)-([^0-9]+)(.*)', config.variant_triple).groups()
+    return run_os
+
+if get_target_os() in ['windows-msvc']:
+    config.substitutions.insert(0, ('%target-abi', 'WIN'))
+    config.substitutions.insert(
+        0,
+        (
+            '%swift-build-cxx-plugin',
+            '%clang -isysroot %host_sdk -I %swift_src_root/include -L %swift-lib-dir -l_swiftMockPlugin'
+        )
+    )
+else:
+    # FIXME(compnerd) do all the targets we currently support use SysV ABI?
+    config.substitutions.insert(0, ('%target-abi', 'SYSV'))
+    config.substitutions.insert(
+        0,
+        (
+            '%swift-build-cxx-plugin',
+            '%clang -isysroot %host_sdk -I %swift_src_root/include -L %swift-lib-dir -l_swiftMockPlugin -Xlinker -rpath -Xlinker %swift-lib-dir'
+        )
+    )
diff --git a/test/Macros/macro_expand.swift b/test/Macros/macro_expand.swift
index 0ed70ec49448d..1e98a656e5db3 100644
--- a/test/Macros/macro_expand.swift
+++ b/test/Macros/macro_expand.swift
@@ -1,7 +1,7 @@
 // REQUIRES: swift_swift_parser, executable_test
 
 // RUN: %empty-directory(%t)
-// RUN: %host-build-swift -swift-version 5 -emit-library -o %t/%target-library-name(MacroDefinition) -module-name=MacroDefinition %S/Inputs/syntax_macro_definitions.swift -g -no-toolchain-stdlib-rpath -swift-version 5
+// RUN: %host-build-swift -swift-version 5 -emit-library -o %t/%target-library-name(MacroDefinition) -module-name=MacroDefinition %S/Inputs/syntax_macro_definitions.swift
 
 // Diagnostics testing
 // RUN: %target-typecheck-verify-swift -swift-version 5 -load-plugin-library %t/%target-library-name(MacroDefinition) -module-name MacroUser -DTEST_DIAGNOSTICS
diff --git a/test/Macros/macro_expand_other.swift b/test/Macros/macro_expand_other.swift
index d6c21f7e0f3f2..cac2ca04f9983 100644
--- a/test/Macros/macro_expand_other.swift
+++ b/test/Macros/macro_expand_other.swift
@@ -1,15 +1,16 @@
 // Expanding macros that are defined in terms of other macros.
 
 // RUN: %empty-directory(%t)
-// RUN: %host-build-swift -swift-version 5 -emit-library -o %t/%target-library-name(MacroDefinition) -parse-as-library -module-name=MacroDefinition %S/Inputs/syntax_macro_definitions.swift -g -no-toolchain-stdlib-rpath
+// RUN: %host-build-swift -swift-version 5 -emit-library -o %t/%target-library-name(MacroDefinition) -parse-as-library -module-name=MacroDefinition %S/Inputs/syntax_macro_definitions.swift
 
 // Diagnostics testing
-// RUN: %target-typecheck-verify-swift -swift-version 5 -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir -module-name MacroUser -DTEST_DIAGNOSTICS
+// RUN: %target-typecheck-verify-swift -swift-version 5 -load-plugin-library %t/%target-library-name(MacroDefinition) -module-name MacroUser -DTEST_DIAGNOSTICS
 
 // Execution testing
-// RUN: %target-build-swift -swift-version 5 -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir -L %swift-host-lib-dir %s -o %t/main -module-name MacroUser
+// RUN: %target-build-swift -swift-version 5 -load-plugin-library %t/%target-library-name(MacroDefinition) %s -o %t/main -module-name MacroUser
 // RUN: %target-codesign %t/main
 // RUN: %target-run %t/main | %FileCheck %s
+
 // REQUIRES: swift_swift_parser, executable_test
 
 @freestanding(expression) macro stringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "MacroDefinition", type: "StringifyMacro")
diff --git a/test/Macros/macro_plugin_basic.swift b/test/Macros/macro_plugin_basic.swift
index 1280c11f937a1..6bcfa7a89d264 100644
--- a/test/Macros/macro_plugin_basic.swift
+++ b/test/Macros/macro_plugin_basic.swift
@@ -3,30 +3,24 @@
 // RUN: %empty-directory(%t)
 // RUN: split-file %s %t
 
-// RUN: %clang \
-// RUN:  -isysroot %host_sdk \
-// RUN:  -I %swift_src_root/include \
-// RUN:  -L %swift-lib-dir -l_swiftMockPlugin \
-// RUN:  -Wl,-rpath,%swift-lib-dir \
-// RUN:  -o %t/mock-plugin \
-// RUN:  %t/plugin.c
+// RUN: %swift-build-cxx-plugin -o %t/mock-plugin %t/plugin.c
 
-// RUN: SWIFT_DUMP_PLUGIN_MESSAGING=1 %swift-target-frontend \
+// RUN: env SWIFT_DUMP_PLUGIN_MESSAGING=1 %swift-target-frontend \
 // RUN:   -typecheck -verify \
 // RUN:   -swift-version 5 \
 // RUN:   -load-plugin-executable %t/mock-plugin#TestPlugin \
 // RUN:   -module-name MyApp \
 // RUN:   %t/test.swift \
-// RUN:   2>&1 | tee %t/macro-expansions.txt
+// RUN:   > %t/macro-expansions.txt 2>&1
 
 // RUN: %FileCheck -strict-whitespace %s < %t/macro-expansions.txt
 
 // CHECK: ->(plugin:[[#PID:]]) {"getCapability":{"capability":{"protocolVersion":[[#PROTOCOL_VERSION:]]}}}
 // CHECK: <-(plugin:[[#PID]]) {"getCapabilityResult":{"capability":{"protocolVersion":1}}}
-// CHECK: ->(plugin:[[#PID]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"testString","typeName":"TestStringMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"BUILD_DIR{{.+}}test.swift","line":5,"offset":301},"source":"#testString(123)"}}}
+// CHECK: ->(plugin:[[#PID]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"testString","typeName":"TestStringMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"{{.+}}test.swift","line":5,"offset":301},"source":"#testString(123)"}}}
 // CHECK: <-(plugin:[[#PID]]) {"expandFreestandingMacroResult":{"diagnostics":[],"expandedSource":"\"123\"\n  +   \"foo  \""}}
-// CHECK: ->(plugin:[[#PID]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"testStringWithError","typeName":"TestStringWithErrorMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"BUILD_DIR{{.+}}test.swift","line":6,"offset":336},"source":"#testStringWithError(321)"}}}
-// CHECK: <-(plugin:[[#PID]]) {"expandFreestandingMacroResult":{"diagnostics":[{"fixIts":[],"highlights":[],"message":"message from plugin","notes":[],"position":{"fileName":"BUILD_DIR{{.*}}test.swift","offset":336},"severity":"error"}],"expandedSource":"\"bar\""}}
+// CHECK: ->(plugin:[[#PID]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"testStringWithError","typeName":"TestStringWithErrorMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"{{.+}}test.swift","line":6,"offset":336},"source":"#testStringWithError(321)"}}}
+// CHECK: <-(plugin:[[#PID]]) {"expandFreestandingMacroResult":{"diagnostics":[{"fixIts":[],"highlights":[],"message":"message from plugin","notes":[],"position":{"fileName":"{{.*}}test.swift","offset":336},"severity":"error"}],"expandedSource":"\"bar\""}}
 
 //--- test.swift
 @freestanding(expression) macro testString(_: Any) -> String = #externalMacro(module: "TestPlugin", type: "TestStringMacro")
diff --git a/test/Macros/macro_plugin_broken.swift b/test/Macros/macro_plugin_broken.swift
index 6ec89f4050ffb..cd20d18a96c83 100644
--- a/test/Macros/macro_plugin_broken.swift
+++ b/test/Macros/macro_plugin_broken.swift
@@ -6,8 +6,7 @@
 // RUN: %host-build-swift \
 // RUN:   -swift-version 5 -o %t/broken-plugin \
 // RUN:   -module-name=TestPlugin \
-// RUN:   %t/broken_plugin.swift \
-// RUN:   -g -no-toolchain-stdlib-rpath -swift-version 5
+// RUN:   %t/broken_plugin.swift
 
 // RUN: not %swift-target-frontend \
 // RUN:   -typecheck \
diff --git a/test/Macros/macro_plugin_error.swift b/test/Macros/macro_plugin_error.swift
index ebab709d4798c..e50edef4dc89b 100644
--- a/test/Macros/macro_plugin_error.swift
+++ b/test/Macros/macro_plugin_error.swift
@@ -3,34 +3,28 @@
 // RUN: %empty-directory(%t)
 // RUN: split-file %s %t
 
-// RUN: %clang \
-// RUN:  -isysroot %host_sdk \
-// RUN:  -I %swift_src_root/include \
-// RUN:  -L %swift-lib-dir -l_swiftMockPlugin \
-// RUN:  -Wl,-rpath,%swift-lib-dir \
-// RUN:  -o %t/mock-plugin \
-// RUN:  %t/plugin.c
+// RUN: %swift-build-cxx-plugin -o %t/mock-plugin %t/plugin.c
 
-// RUN: SWIFT_DUMP_PLUGIN_MESSAGING=1 %swift-target-frontend \
+// RUN: env SWIFT_DUMP_PLUGIN_MESSAGING=1 %swift-target-frontend \
 // RUN:   -typecheck -verify \
 // RUN:   -swift-version 5 -enable-experimental-feature Macros \
 // RUN:   -load-plugin-executable %t/mock-plugin#TestPlugin \
 // RUN:   -module-name MyApp \
 // RUN:   %t/test.swift \
-// RUN:   2>&1 | tee %t/macro-expansions.txt
+// RUN:   > %t/macro-expansions.txt 2>&1
 
 // RUN: %FileCheck -strict-whitespace %s < %t/macro-expansions.txt
 
 // CHECK: ->(plugin:[[#PID1:]]) {"getCapability":{"capability":{"protocolVersion":[[#PROTOCOL_VERSION:]]}}}
 // CHECK-NEXT: <-(plugin:[[#PID1]]) {"getCapabilityResult":{"capability":{"protocolVersion":1}}}
-// CHECK-NEXT: ->(plugin:[[#PID1]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"fooMacro","typeName":"FooMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"BUILD_DIR{{.+}}test.swift","line":6,"offset":[[#]]},"source":"#fooMacro(1)"}}}
+// CHECK-NEXT: ->(plugin:[[#PID1]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"fooMacro","typeName":"FooMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"{{.+}}test.swift","line":6,"offset":[[#]]},"source":"#fooMacro(1)"}}}
 // CHECK-NEXT: <-(plugin:[[#PID1]]) {"invalidResponse":{}}
-// CHECK-NEXT: ->(plugin:[[#PID1]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"fooMacro","typeName":"FooMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"BUILD_DIR{{.+}}test.swift","line":8,"offset":[[#]]},"source":"#fooMacro(2)"}}}
+// CHECK-NEXT: ->(plugin:[[#PID1]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"fooMacro","typeName":"FooMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"{{.+}}test.swift","line":8,"offset":[[#]]},"source":"#fooMacro(2)"}}}
 // ^ This messages causes the mock plugin exit because there's no matching expected message.
 
 // CHECK: ->(plugin:[[#PID2:]]) {"getCapability":{"capability":{"protocolVersion":[[#PROTOCOL_VERSION]]}}}
 // CHECK-NEXT: <-(plugin:[[#PID2]]) {"getCapabilityResult":{"capability":{"protocolVersion":1}}}
-// CHECK-NEXT: ->(plugin:[[#PID2]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"fooMacro","typeName":"FooMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"BUILD_DIR{{.+}}test.swift","line":10,"offset":[[#]]},"source":"#fooMacro(3)"}}}
+// CHECK-NEXT: ->(plugin:[[#PID2]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","macro":{"moduleName":"TestPlugin","name":"fooMacro","typeName":"FooMacro"},"macroRole":"expression","syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"{{.+}}test.swift","line":10,"offset":[[#]]},"source":"#fooMacro(3)"}}}
 // CHECK-NEXT: <-(plugin:[[#PID2:]]) {"expandFreestandingMacroResult":{"diagnostics":[],"expandedSource":"3.description"}}
 
 //--- test.swift
diff --git a/test/Macros/macro_plugin_searchorder.swift b/test/Macros/macro_plugin_searchorder.swift
index 562144fa86b48..2373e09c95ac2 100644
--- a/test/Macros/macro_plugin_searchorder.swift
+++ b/test/Macros/macro_plugin_searchorder.swift
@@ -18,8 +18,7 @@
 // RUN:   -emit-library -o %t/lib/plugins/%target-library-name(MacroDefinition) \
 // RUN:   -module-name MacroDefinition \
 // RUN:   -D PLUGIN_PATH \
-// RUN:   %t/src/MacroDefinition.swift \
-// RUN:   -g -no-toolchain-stdlib-rpath
+// RUN:   %t/src/MacroDefinition.swift
 
 //#-- For -load-plugin-library
 // RUN: %host-build-swift \
@@ -27,8 +26,7 @@
 // RUN:   -emit-library -o %t/lib/tmp/%target-library-name(MacroDefinition) \
 // RUN:   -module-name MacroDefinition \
 // RUN:   -D LOAD_PLUGIN_LIBRARY \
-// RUN:   %t/src/MacroDefinition.swift \
-// RUN:   -g -no-toolchain-stdlib-rpath
+// RUN:   %t/src/MacroDefinition.swift
 
 //#-- For -external-plugin-path
 // RUN: %host-build-swift \
@@ -36,17 +34,10 @@
 // RUN:   -emit-library -o %t/external/%target-library-name(MacroDefinition) \
 // RUN:   -module-name MacroDefinition \
 // RUN:   -D EXTERNAL_PLUGIN_PATH \
-// RUN:   %t/src/MacroDefinition.swift \
-// RUN:   -g -no-toolchain-stdlib-rpath
+// RUN:   %t/src/MacroDefinition.swift
 
 //#-- For -load-plugin-executable
-// RUN: %clang \
-// RUN:  -isysroot %host_sdk \
-// RUN:  -I %swift_src_root/include \
-// RUN:  -L %swift-lib-dir -l_swiftMockPlugin \
-// RUN:  -Wl,-rpath,%swift-lib-dir \
-// RUN:  -o %t/libexec/MacroDefinitionPlugin \
-// RUN:  %t/src/MacroDefinition.c
+// RUN: %swift-build-cxx-plugin -o %t/libexec/MacroDefinitionPlugin %t/src/MacroDefinition.c
 
 //#-- Expect -load-plugin-library
 // RUN: %target-build-swift %t/src/test.swift \
diff --git a/test/Macros/macro_swiftdeps.swift b/test/Macros/macro_swiftdeps.swift
index 2b6438e7ffada..118ef1cc364ad 100644
--- a/test/Macros/macro_swiftdeps.swift
+++ b/test/Macros/macro_swiftdeps.swift
@@ -12,17 +12,10 @@
 // RUN:   -swift-version 5 \
 // RUN:   -emit-library -o %t/plugin/%target-library-name(MacroDefinition) \
 // RUN:   -module-name MacroDefinition \
-// RUN:   %S/Inputs/syntax_macro_definitions.swift \
-// RUN:   -g -no-toolchain-stdlib-rpath
+// RUN:   %S/Inputs/syntax_macro_definitions.swift
 
 //#-- Prepare the macro executable plugin.
-// RUN: %clang \
-// RUN:  -isysroot %host_sdk \
-// RUN:  -I %swift_src_root/include \
-// RUN:  -L %swift-lib-dir -l_swiftMockPlugin \
-// RUN:  -Wl,-rpath,%swift-lib-dir \
-// RUN:  -o %t/mock-plugin \
-// RUN:  %t/src/plugin.c
+// RUN: %swift-build-cxx-plugin -o %t/mock-plugin %t/src/plugin.c
 
 //#-- Prepare the macro library.
 // RUN: %target-swift-frontend \
@@ -34,7 +27,7 @@
 // RUN:   -primary-file %t/src/macro_library.swift \
 // RUN:   -emit-reference-dependencies-path %t/macro_library.swiftdeps \
 // RUN:   -emit-dependencies-path %t/macro_library.d
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t/macro_library.swiftdeps %t/macro_library.swiftdeps.processed
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t/macro_library.swiftdeps > %t/macro_library.swiftdeps.processed
 // RUN: %FileCheck --check-prefix WITH_PLUGIN %s < %t/macro_library.swiftdeps.processed
 
 //#-- Without macro (no -D USE_MACRO)
@@ -46,7 +39,7 @@
 // RUN:   -load-plugin-executable %t/mock-plugin#TestPlugin \
 // RUN:   -emit-reference-dependencies-path %t/without_macro.swiftdeps \
 // RUN:   -emit-dependencies-path %t/without_macro.d
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t/without_macro.swiftdeps %t/without_macro.swiftdeps.processed
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t/without_macro.swiftdeps > %t/without_macro.swiftdeps.processed
 // RUN: %FileCheck --check-prefix WITHOUT_PLUGIN %s < %t/without_macro.swiftdeps.processed
 
 //#-- With macro - primary (-D USE_MACRO)
@@ -59,7 +52,7 @@
 // RUN:   -load-plugin-executable %t/mock-plugin#TestPlugin \
 // RUN:   -emit-reference-dependencies-path %t/with_macro_primary.swiftdeps \
 // RUN:   -emit-dependencies-path %t/with_macro_primary.d
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t/with_macro_primary.swiftdeps %t/with_macro_primary.swiftdeps.processed
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t/with_macro_primary.swiftdeps > %t/with_macro_primary.swiftdeps.processed
 // RUN: %FileCheck --check-prefix WITH_PLUGIN %s < %t/with_macro_primary.swiftdeps.processed
 
 //#-- With macro - non-primary (-D USE_MACRO)
@@ -72,11 +65,11 @@
 // RUN:   -load-plugin-executable %t/mock-plugin#TestPlugin \
 // RUN:   -emit-reference-dependencies-path %t/with_macro_nonprimary.swiftdeps \
 // RUN:   -emit-dependencies-path %t/with_macro_nonprimary.d
-// RUN: %S/../Inputs/process_fine_grained_swiftdeps.sh %swift-dependency-tool %t/with_macro_nonprimary.swiftdeps %t/with_macro_nonprimary.swiftdeps.processed
+// RUN: %{python} %S/../Inputs/process_fine_grained_swiftdeps.py %swift-dependency-tool %t/with_macro_nonprimary.swiftdeps > %t/with_macro_nonprimary.swiftdeps.processed
 // RUN: %FileCheck --check-prefix WITHOUT_PLUGIN %s < %t/with_macro_nonprimary.swiftdeps.processed
 
-// WITH_PLUGIN: externalDepend interface '' 'BUILD_DIR{{.*}}mock-plugin' false
-// WITH_PLUGIN: externalDepend interface '' 'BUILD_DIR{{.*}}libMacroDefinition.{{(dylib|so|dll)}}' false
+// WITH_PLUGIN: externalDepend interface '' '{{.*}}mock-plugin' false
+// WITH_PLUGIN: externalDepend interface '' '{{.*}}MacroDefinition.{{(dylib|so|dll)}}' false
 
 // WITHOUT_PLUGIN-NOT:  MacroDefinition
 // WITHOUT_PLUGIN-NOT:  mock-plugin
diff --git a/test/Macros/option_set.swift b/test/Macros/option_set.swift
index eda8136594651..ce9d87ba81a50 100644
--- a/test/Macros/option_set.swift
+++ b/test/Macros/option_set.swift
@@ -1,6 +1,6 @@
 // REQUIRES: swift_swift_parser, executable_test
 
-// RUN: %target-run-simple-swift(-Xfrontend -plugin-path -Xfrontend %swift-host-lib-dir/plugins -emit-tbd -emit-tbd-path %t.tbd)
+// RUN: %target-run-simple-swift(-Xfrontend -plugin-path -Xfrontend %swift-plugin-dir -emit-tbd -emit-tbd-path %t.tbd)
 
 import Swift
 
diff --git a/test/Macros/serialize_plugin_search_paths.swift b/test/Macros/serialize_plugin_search_paths.swift
index cd4b53fc4725f..9295e124f8e46 100644
--- a/test/Macros/serialize_plugin_search_paths.swift
+++ b/test/Macros/serialize_plugin_search_paths.swift
@@ -16,5 +16,5 @@
 // CHECK:     -external-plugin-path {{.*}}plugins#{{.*}}swift-plugin-server
 // CHECK:     -load-plugin-library {{.*}}MacroDefinition.{{dylib|so|dll}}
 // CHECK:     -load-plugin-executable {{.*}}mock-plugin#TestPlugin
-// CHECK:     -plugin-path {{.*}}plugins
-// CHECK:     -plugin-path {{.*}}plugins
+// CHECK-SYSV:-plugin-path {{.*}}plugins
+// CHECK-SYSV:-plugin-path {{.*}}plugins
diff --git a/test/ModuleInterface/Observable.swift b/test/ModuleInterface/Observable.swift
index 59a571a226659..ce62c8d99be32 100644
--- a/test/ModuleInterface/Observable.swift
+++ b/test/ModuleInterface/Observable.swift
@@ -1,5 +1,5 @@
 // RUN: %empty-directory(%t)
-// RUN: %target-swift-emit-module-interface(%t/Library.swiftinterface) %s -module-name Library -plugin-path %swift-host-lib-dir/plugins -disable-availability-checking
+// RUN: %target-swift-emit-module-interface(%t/Library.swiftinterface) %s -module-name Library -plugin-path %swift-plugin-dir -disable-availability-checking
 // RUN: %target-swift-typecheck-module-from-interface(%t/Library.swiftinterface) -module-name Library -disable-availability-checking
 // RUN: %FileCheck %s < %t/Library.swiftinterface
 
diff --git a/test/lit.cfg b/test/lit.cfg
index 76d61f614b7dd..35d6ac55029a7 100644
--- a/test/lit.cfg
+++ b/test/lit.cfg
@@ -524,7 +524,14 @@ shutil.rmtree(completion_cache_path, ignore_errors=True)
 ccp_opt = "-completion-cache-path %r" % completion_cache_path
 lit_config.note("Using code completion cache: " + completion_cache_path)
 
-config.swift_host_lib_dir = make_path(config.swift_lib_dir, 'swift', 'host')
+if kIsWindows:
+    config.swift_plugin_dir = config.swift_bin_dir
+    # FIXME: this is a workaround for the collsion between the build toolchain
+    # and the current build, this should be `make_path(config.swift_lib_dir, 'swift')`
+    config.swift_build_lib_dir = make_path(config.swift_lib_dir, 'swift', 'host')
+else:
+    config.swift_plugin_dir = make_path(config.swift_lib_dir, 'swift', 'host', 'plugins')
+    config.swift_build_lib_dir = make_path(config.swift_lib_dir, 'swift', 'host')
 
 if platform.system() == 'Darwin':
     config.swift_driver = (
@@ -534,8 +541,14 @@ if platform.system() == 'Darwin':
         "env SDKROOT=%s %r -toolchain-stdlib-rpath -Xlinker -rpath -Xlinker /usr/lib/swift %s %s %s"
         % (shell_quote(config.host_sdkroot), config.swiftc, mcp_opt, config.swift_test_options, config.swift_driver_test_options))
     config.host_build_swift = (
-        "%s -sdk %s -target %s -I %s -L %s"
-        % (config.swiftc_driver, config.host_sdkroot, config.host_triple, config.swift_host_lib_dir, config.swift_host_lib_dir))
+        "%s -sdk %s -target %s -no-toolchain-stdlib-rpath -I %s -L %s" % (
+            config.swiftc_driver,
+            config.host_sdkroot,
+            config.host_triple,
+            config.swift_build_lib_dir,
+            config.swift_build_lib_dir
+        )
+    )
 else:
     config.swift_driver = (
         "%r %s %s %s"
@@ -543,18 +556,31 @@ else:
     if kIsWindows:
         config.swift_driver += " -libc " + config.swift_stdlib_msvc_runtime
     config.swiftc_driver = (
-        "%r -toolchain-stdlib-rpath %s %s %s"
-        % (config.swiftc, mcp_opt, config.swift_test_options, config.swift_driver_test_options))
+        "%r %s %s %s %s" % (
+            config.swiftc,
+            '' if kIsWindows else '-toolchain-stdlib-rpath',
+            mcp_opt,
+            config.swift_test_options,
+            config.swift_driver_test_options,
+        )
+    )
     # Parse the host triple.
     (host_cpu, host_vendor, host_os, host_vers) = re.match('([^-]+)-([^-]+)-([^0-9-]+)(.*)', config.host_triple).groups()
     toolchain_lib_dir = make_path(config.swift_lib_dir, 'swift', host_os)
     config.host_build_swift = (
-        "%s -target %s -I %s -L %s -Xlinker -rpath -Xlinker %s"
-        % (config.swiftc_driver, config.host_triple, config.swift_host_lib_dir, config.swift_host_lib_dir, toolchain_lib_dir))
+        "%s -target %s -g %s -I %s -L %s %s" % (
+            config.swiftc_driver,
+            config.host_triple,
+            '' if kIsWindows else '-no-toolchain-stdlib-rpath',
+            config.swift_build_lib_dir,
+            config.swift_build_lib_dir,
+            '' if kIsWindows else '-Xlinker -rpath -Xlinker {}'.format(toolchain_lib_dir)
+        )
+    )
 
 config.substitutions.append( ('%llvm_obj_root', config.llvm_obj_root) )
 config.substitutions.append( ('%swift-lib-dir', config.swift_lib_dir) )
-config.substitutions.append( ('%swift-host-lib-dir', config.swift_host_lib_dir))
+config.substitutions.append( ('%swift-plugin-dir', config.swift_plugin_dir) )
 config.substitutions.append( ('%llvm_src_root', config.llvm_src_root) )
 config.substitutions.append( ('%swift_obj_root', config.swift_obj_root) )
 config.substitutions.append( ('%swift_src_root', config.swift_src_root) )
@@ -2651,9 +2677,9 @@ config.substitutions.append(('%llvm-cov', config.llvm_cov))
 if hasattr(config, 'target_library_path_var'):
   host_library_env = (
           "/usr/bin/env " +
-          construct_library_path_env([config.swift_host_lib_dir]))
+          construct_library_path_env([make_path(config.swift_lib_dir, 'swift', 'host')]))
 else:
-  host_library_env = "env"
+  host_library_env = ""
 
 config.substitutions.append(('%host-library-env', host_library_env))
 
diff --git a/test/stdlib/Observation/Observable.swift b/test/stdlib/Observation/Observable.swift
index 83fa7dca33103..a01117ebb5431 100644
--- a/test/stdlib/Observation/Observable.swift
+++ b/test/stdlib/Observation/Observable.swift
@@ -1,9 +1,9 @@
 // REQUIRES: swift_swift_parser, executable_test
 
-// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -parse-as-library -enable-experimental-feature Macros -enable-experimental-feature ExtensionMacros -Xfrontend -plugin-path -Xfrontend %swift-host-lib-dir/plugins)
+// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -parse-as-library -enable-experimental-feature Macros -enable-experimental-feature ExtensionMacros -Xfrontend -plugin-path -Xfrontend %swift-plugin-dir)
 
 // Run this test via the swift-plugin-server
-// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -parse-as-library -enable-experimental-feature Macros -enable-experimental-feature ExtensionMacros -Xfrontend -external-plugin-path -Xfrontend %swift-host-lib-dir/plugins#%swift-plugin-server)
+// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -parse-as-library -enable-experimental-feature Macros -enable-experimental-feature ExtensionMacros -Xfrontend -external-plugin-path -Xfrontend %swift-plugin-dir#%swift-plugin-server)
 
 // REQUIRES: observation
 // REQUIRES: concurrency
diff --git a/test/stdlib/Observation/ObservableAvailabilityCycle.swift b/test/stdlib/Observation/ObservableAvailabilityCycle.swift
index 74a305d7216f3..7e1f20bd352fb 100644
--- a/test/stdlib/Observation/ObservableAvailabilityCycle.swift
+++ b/test/stdlib/Observation/ObservableAvailabilityCycle.swift
@@ -1,8 +1,8 @@
 // REQUIRES: swift_swift_parser
 
-// RUN: %target-swift-frontend -typecheck -parse-as-library -external-plugin-path %swift-host-lib-dir/plugins#%swift-plugin-server -primary-file %s %S/Inputs/ObservableClass.swift
+// RUN: %target-swift-frontend -typecheck -parse-as-library -external-plugin-path %swift-plugin-dir#%swift-plugin-server -primary-file %s %S/Inputs/ObservableClass.swift
 
-// RUN: %target-swift-frontend -typecheck -parse-as-library -external-plugin-path %swift-host-lib-dir/plugins#%swift-plugin-server %s -primary-file %S/Inputs/ObservableClass.swift
+// RUN: %target-swift-frontend -typecheck -parse-as-library -external-plugin-path %swift-plugin-dir#%swift-plugin-server %s -primary-file %S/Inputs/ObservableClass.swift
 
 // REQUIRES: observation
 // REQUIRES: concurrency
diff --git a/test/stdlib/Observation/ObservableDidSetWillSet.swift b/test/stdlib/Observation/ObservableDidSetWillSet.swift
index ffa9ecb649700..e990d2d1881e8 100644
--- a/test/stdlib/Observation/ObservableDidSetWillSet.swift
+++ b/test/stdlib/Observation/ObservableDidSetWillSet.swift
@@ -1,6 +1,6 @@
 // REQUIRES: swift_swift_parser, executable_test
 
-// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -enable-experimental-feature Macros -enable-experimental-feature ExtensionMacros -Xfrontend -plugin-path -Xfrontend %swift-host-lib-dir/plugins) | %FileCheck %s
+// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -enable-experimental-feature Macros -enable-experimental-feature ExtensionMacros -Xfrontend -plugin-path -Xfrontend %swift-plugin-dir) | %FileCheck %s
 
 // REQUIRES: observation
 // REQUIRES: concurrency
diff --git a/tools/SourceKit/cmake/modules/AddSwiftSourceKit.cmake b/tools/SourceKit/cmake/modules/AddSwiftSourceKit.cmake
index 7e2e1bc16e763..5514431eea9ce 100644
--- a/tools/SourceKit/cmake/modules/AddSwiftSourceKit.cmake
+++ b/tools/SourceKit/cmake/modules/AddSwiftSourceKit.cmake
@@ -162,6 +162,9 @@ function(add_sourcekit_swift_runtime_link_flags target path HAS_SWIFT_MODULES)
       file(RELATIVE_PATH relative_hostlib_path "${path}" "${SWIFTLIB_DIR}/host")
       list(APPEND RPATH_LIST "$ORIGIN/${relative_hostlib_path}")
     endif()
+  else()
+    target_link_directories(${target} PRIVATE
+      ${SWIFT_PATH_TO_SWIFT_SDK}/usr/lib/swift/${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}/${SWIFT_HOST_VARIANT_ARCH})
   endif()
 
   if(SWIFT_SWIFT_PARSER)
diff --git a/tools/SourceKit/tools/sourcekitd-test/sourcekitd-test.cpp b/tools/SourceKit/tools/sourcekitd-test/sourcekitd-test.cpp
index ff383ae105462..1f72f36c5f9e6 100644
--- a/tools/SourceKit/tools/sourcekitd-test/sourcekitd-test.cpp
+++ b/tools/SourceKit/tools/sourcekitd-test/sourcekitd-test.cpp
@@ -427,7 +427,7 @@ static bool setSyntacticMacroExpansions(sourcekitd_object_t req,
   SmallVector<sourcekitd_object_t, 4> expansions;
   for (std::string &opt : opts.RequestOptions) {
     SmallVector<StringRef, 3> args;
-    StringRef(opt).split(args, ":");
+    StringRef(opt).split(args, ":", /*maxSplits=*/2);
     unsigned line, column;
 
     if (args.size() != 3 || args[0].getAsInteger(10, line) ||
diff --git a/tools/driver/CMakeLists.txt b/tools/driver/CMakeLists.txt
index 649510e8771fa..9c2e5ed6486a9 100644
--- a/tools/driver/CMakeLists.txt
+++ b/tools/driver/CMakeLists.txt
@@ -5,6 +5,8 @@
 # parser is built in.
 function(add_swift_parser_link_libraries target)
   if(SWIFT_SWIFT_PARSER)
+    target_link_directories(${target} PRIVATE
+      ${SWIFT_PATH_TO_SWIFT_SDK}/usr/lib/swift/${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}/${SWIFT_HOST_VARIANT_ARCH})
     target_link_libraries(${target}
                           PRIVATE swiftCore)
 
diff --git a/tools/swift-plugin-server/CMakeLists.txt b/tools/swift-plugin-server/CMakeLists.txt
index 09332309b10c9..1d1b88b22bd8a 100644
--- a/tools/swift-plugin-server/CMakeLists.txt
+++ b/tools/swift-plugin-server/CMakeLists.txt
@@ -16,6 +16,8 @@ if (SWIFT_SWIFT_PARSER)
     DEPENDENCIES
       swiftDemangling
       $<TARGET_OBJECTS:_swiftCSwiftPluginServer>
+    SWIFT_COMPONENT
+      compiler
     SWIFT_DEPENDENCIES
       SwiftSyntax::SwiftSyntaxMacros
       SwiftSyntax::SwiftSyntaxMacroExpansion
@@ -25,9 +27,4 @@ if (SWIFT_SWIFT_PARSER)
   target_include_directories(swift-plugin-server PRIVATE
     Sources/CSwiftPluginServer/include
   )
-  swift_install_in_component(TARGETS swift-plugin-server
-    RUNTIME
-      DESTINATION bin
-      COMPONENT compiler
-  )
 endif()
diff --git a/tools/swift-plugin-server/Sources/CSwiftPluginServer/PluginServer.cpp b/tools/swift-plugin-server/Sources/CSwiftPluginServer/PluginServer.cpp
index 707b40a5d182c..a689f18d8ebc8 100644
--- a/tools/swift-plugin-server/Sources/CSwiftPluginServer/PluginServer.cpp
+++ b/tools/swift-plugin-server/Sources/CSwiftPluginServer/PluginServer.cpp
@@ -13,11 +13,17 @@
 #include "PluginServer.h"
 #include "swift/ABI/MetadataValues.h"
 #include "swift/Demangling/Demangle.h"
+#include "llvm/Support/DynamicLibrary.h"
 
+#if defined(_WIN32)
+#include <io.h>
+#elif defined(__unix__) || defined(__APPLE__)
 #include <dlfcn.h>
+#include <unistd.h>
+#endif
+
 #include <errno.h>
 #include <string.h>
-#include <unistd.h>
 
 using namespace swift;
 
@@ -32,6 +38,46 @@ struct ConnectionHandle {
 } // namespace
 
 const void *PluginServer_createConnection(const char **errorMessage) {
+#if defined(_WIN32)
+  struct unique_fd {
+    unique_fd(int fd) : fd_(fd) {}
+    unique_fd(const unique_fd &) = delete;
+    unique_fd &operator=(const unique_fd &) = delete;
+    unique_fd &operator=(unique_fd &&) = delete;
+    unique_fd(unique_fd &&uf) : fd_(uf.fd_) { uf.fd_ = -1; }
+    ~unique_fd() { if (fd_ > 0) _close(fd_); }
+
+    int operator*() const { return fd_; }
+    int release() { int fd = fd_; fd_ = -1; return fd; }
+
+  private:
+    int fd_;
+  };
+
+  unique_fd ifd{_dup(_fileno(stdin))};
+  if (*ifd < 0) {
+    *errorMessage = _strerror(nullptr);
+    return nullptr;
+  }
+
+  if (_close(_fileno(stdin)) < 0) {
+    *errorMessage = _strerror(nullptr);
+    return nullptr;
+  }
+
+  unique_fd ofd{_dup(_fileno(stdout))};
+  if (*ofd < 0) {
+    *errorMessage = _strerror(nullptr);
+    return nullptr;
+  }
+
+  if (_dup2(_fileno(stderr), _fileno(stdout)) < 0) {
+    *errorMessage = _strerror(nullptr);
+    return nullptr;
+  }
+
+  return new ConnectionHandle(ifd.release(), ofd.release());
+#else
   // Duplicate the `stdin` file descriptor, which we will then use for
   // receiving messages from the plugin host.
   auto inputFD = dup(STDIN_FILENO);
@@ -65,37 +111,48 @@ const void *PluginServer_createConnection(const char **errorMessage) {
 
   // Open a message channel for communicating with the plugin host.
   return new ConnectionHandle(inputFD, outputFD);
+#endif
 }
 
-void PluginServer_destroyConnection(const void *connHandle) {
-  const auto *conn = static_cast<const ConnectionHandle *>(connHandle);
-  delete conn;
+void PluginServer_destroyConnection(const void *server) {
+  delete static_cast<const ConnectionHandle *>(server);
 }
 
-long PluginServer_read(const void *connHandle, void *data,
-                       unsigned long nbyte) {
-  const auto *conn = static_cast<const ConnectionHandle *>(connHandle);
-  return ::read(conn->inputFD, data, nbyte);
+SwiftInt PluginServer_read(const void *server, void *data, SwiftUInt nbyte) {
+  const auto *connection = static_cast<const ConnectionHandle *>(server);
+#if defined(_WIN32)
+  return _read(connection->inputFD, data, nbyte);
+#else
+  return ::read(connection->inputFD, data, nbyte);
+#endif
 }
 
-long PluginServer_write(const void *connHandle, const void *data,
-                        unsigned long nbyte) {
-  const auto *conn = static_cast<const ConnectionHandle *>(connHandle);
-  return ::write(conn->outputFD, data, nbyte);
+SwiftInt PluginServer_write(const void *server, const void *data, SwiftUInt nbyte) {
+  const auto *connection = static_cast<const ConnectionHandle *>(server);
+#if defined(_WIN32)
+  return _write(connection->outputFD, data, nbyte);
+#else
+  return ::write(connection->outputFD, data, nbyte);
+#endif
 }
 
-void *PluginServer_dlopen(const char *filename, const char **errorMessage) {
-  auto *handle = ::dlopen(filename, RTLD_LAZY | RTLD_LOCAL);
-  if (!handle) {
-    *errorMessage = dlerror();
-  }
-  return handle;
+void *PluginServer_load(const char *plugin, const char **errorMessage) {
+  // Use a static allocation for the error as the client will not release the
+  // string.  POSIX 2008 (IEEE-1003.1-2008) specifies that it is implementation
+  // defined if `dlerror` is re-entrant.  Take advantage of that and make it
+  // thread-unsafe.  This ensures that the string outlives the call permitting
+  // the client to duplicate it.
+  static std::string error;
+  auto library = llvm::sys::DynamicLibrary::getLibrary(plugin, &error);
+  if (library.isValid())
+    return library.getOSSpecificHandle();
+  *errorMessage = error.c_str();
+  return nullptr;
 }
 
 const void *PluginServer_lookupMacroTypeMetadataByExternalName(
     const char *moduleName, const char *typeName, void *libraryHint,
     const char **errorMessage) {
-
   // Look up the type metadata accessor as a struct, enum, or class.
   const Demangle::Node::Kind typeKinds[] = {
       Demangle::Node::Kind::Structure,
@@ -108,8 +165,12 @@ const void *PluginServer_lookupMacroTypeMetadataByExternalName(
     auto symbolName =
         mangledNameForTypeMetadataAccessor(moduleName, typeName, typeKind);
 
-    auto *handle = libraryHint ? libraryHint : RTLD_DEFAULT;
-    accessorAddr = ::dlsym(handle, symbolName.c_str());
+#if !defined(_WIN32)
+    if (libraryHint == nullptr)
+      libraryHint = RTLD_DEFAULT;
+#endif
+    accessorAddr = llvm::sys::DynamicLibrary{libraryHint}
+                      .getAddressOfSymbol(symbolName.c_str());
     if (accessorAddr)
       break;
   }
diff --git a/tools/swift-plugin-server/Sources/CSwiftPluginServer/include/PluginServer.h b/tools/swift-plugin-server/Sources/CSwiftPluginServer/include/PluginServer.h
index dba78fedf8139..d30c48b86dbc9 100644
--- a/tools/swift-plugin-server/Sources/CSwiftPluginServer/include/PluginServer.h
+++ b/tools/swift-plugin-server/Sources/CSwiftPluginServer/include/PluginServer.h
@@ -13,6 +13,69 @@
 #ifndef SWIFT_PLUGINSERVER_PLUGINSERVER_H
 #define SWIFT_PLUGINSERVER_PLUGINSERVER_H
 
+// NOTE: Partially ported from SwiftShim's SwiftStdint.h. We cannot include
+// that header here because it belongs to the runtime, but we need the same
+// logic for interoperability with Swift code in the compiler itself.
+// stdint.h is provided by Clang, but it dispatches to libc's stdint.h.  As a
+// result, using stdint.h here would pull in Darwin module (which includes
+// libc). This creates a dependency cycle, so we can't use stdint.h in
+// SwiftShims.
+// On Linux, the story is different. We get the error message
+// "/usr/include/x86_64-linux-gnu/sys/types.h:146:10: error: 'stddef.h' file not
+// found"
+// This is a known Clang/Ubuntu bug.
+
+// Clang has been defining __INTxx_TYPE__ macros for a long time.
+// __UINTxx_TYPE__ are defined only since Clang 3.5.
+#if defined(_MSC_VER) && !defined(__clang__)
+typedef __int64 __swiftc_int64_t;
+typedef unsigned __int64 __swiftc_uint64_t;
+typedef int __swiftc_int32_t;
+typedef unsigned int __swiftc_uint32_t;
+#elif !defined(__APPLE__) && !defined(__linux__) && !defined(__OpenBSD__) && !defined(__wasi__)
+#include <stdint.h>
+typedef int64_t __swiftc_int64_t;
+typedef uint64_t __swiftc_uint64_t;
+typedef int32_t __swiftc_int32_t;
+typedef uint32_t __swiftc_uint32_t;
+typedef intptr_t __swiftc_intptr_t;
+typedef uintptr_t __swiftc_uintptr_t;
+#else
+typedef __INT64_TYPE__ __swiftc_int64_t;
+#ifdef __UINT64_TYPE__
+typedef __UINT64_TYPE__ __swiftc_uint64_t;
+#else
+typedef unsigned __INT64_TYPE__ __swiftc_uint64_t;
+#endif
+
+typedef __INT32_TYPE__ __swiftc_int32_t;
+#ifdef __UINT32_TYPE__
+typedef __UINT32_TYPE__ __swiftc_uint32_t;
+#else
+typedef unsigned __INT32_TYPE__ __swiftc_uint32_t;
+#endif
+#endif
+
+#define __swiftc_join3(a,b,c) a ## b ## c
+
+#define __swiftc_intn_t(n) __swiftc_join3(__swiftc_int, n, _t)
+#define __swiftc_uintn_t(n) __swiftc_join3(__swiftc_uint, n, _t)
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#if defined(_WIN64)
+typedef __swiftc_int64_t SwiftInt;
+typedef __swiftc_uint64_t SwiftUInt;
+#elif defined(_WIN32)
+typedef __swiftc_int32_t SwiftInt;
+typedef __swiftc_uint32_t SwiftUInt;
+#else
+#error unknown windows pointer width
+#endif
+#else
+typedef __swiftc_intn_t(__INTPTR_WIDTH__) SwiftInt;
+typedef __swiftc_uintn_t(__INTPTR_WIDTH__) SwiftUInt;
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -29,18 +92,17 @@ const void *PluginServer_createConnection(const char **errorMessage);
 void PluginServer_destroyConnection(const void *connHandle);
 
 /// Read bytes from the IPC communication handle.
-long PluginServer_read(const void *connHandle, void *data, unsigned long nbyte);
+SwiftInt PluginServer_read(const void *connHandle, void *data, SwiftUInt nbyte);
 
 /// Write bytes to the IPC communication handle.
-long PluginServer_write(const void *connHandle, const void *data,
-                        unsigned long nbyte);
+SwiftInt PluginServer_write(const void *connHandle, const void *data, SwiftUInt nbyte);
 
 //===----------------------------------------------------------------------===//
 // Dynamic link
 //===----------------------------------------------------------------------===//
 
 /// Load a dynamic link library, and return the handle.
-void *PluginServer_dlopen(const char *filename, const char **errorMessage);
+void *PluginServer_load(const char *filename, const char **errorMessage);
 
 /// Resolve a type metadata by a pair of the module name and the type name.
 /// 'libraryHint' is a
diff --git a/tools/swift-plugin-server/Sources/swift-plugin-server/swift-plugin-server.swift b/tools/swift-plugin-server/Sources/swift-plugin-server/swift-plugin-server.swift
index e1f8bae8b898a..ad117e4d8e50e 100644
--- a/tools/swift-plugin-server/Sources/swift-plugin-server/swift-plugin-server.swift
+++ b/tools/swift-plugin-server/Sources/swift-plugin-server/swift-plugin-server.swift
@@ -47,7 +47,7 @@ extension SwiftPluginServer: PluginProvider {
   /// Load a macro implementation from the dynamic link library.
   func loadPluginLibrary(libraryPath: String, moduleName: String) throws {
     var errorMessage: UnsafePointer<CChar>?
-    guard let dlHandle = PluginServer_dlopen(libraryPath, &errorMessage) else {
+    guard let dlHandle = PluginServer_load(libraryPath, &errorMessage) else {
       throw PluginServerError(message: String(cString: errorMessage!))
     }
     loadedLibraryPlugins[moduleName] = dlHandle
@@ -172,13 +172,13 @@ final class PluginHostConnection: MessageConnection {
     var ptr = buffer.baseAddress!
 
     while (bytesToWrite > 0) {
-      let writtenSize = PluginServer_write(handle, ptr, UInt(bytesToWrite))
+      let writtenSize = PluginServer_write(handle, ptr, SwiftUInt(bytesToWrite))
       if (writtenSize <= 0) {
         // error e.g. broken pipe.
         break
       }
-      ptr = ptr.advanced(by: writtenSize)
-      bytesToWrite -= writtenSize
+      ptr = ptr.advanced(by: Int(writtenSize))
+      bytesToWrite -= Int(writtenSize)
     }
     return buffer.count - bytesToWrite
   }
@@ -193,13 +193,13 @@ final class PluginHostConnection: MessageConnection {
     var ptr = buffer.baseAddress!
 
     while bytesToRead > 0 {
-      let readSize = PluginServer_read(handle, ptr, UInt(bytesToRead))
+      let readSize = PluginServer_read(handle, ptr, SwiftUInt(bytesToRead))
       if (readSize <= 0) {
         // 0: EOF (the host closed), -1: Broken pipe (the host crashed?)
         break;
       }
-      ptr = ptr.advanced(by: readSize)
-      bytesToRead -= readSize
+      ptr = ptr.advanced(by: Int(readSize))
+      bytesToRead -= Int(readSize)
     }
     return buffer.count - bytesToRead
   }