diff --git a/lib/AST/CASTBridging.cpp b/lib/AST/CASTBridging.cpp
index e629b4057b0e9..dacb9bbc62f65 100644
--- a/lib/AST/CASTBridging.cpp
+++ b/lib/AST/CASTBridging.cpp
@@ -17,6 +17,8 @@ using namespace swift;
 
 namespace {
 struct BridgedDiagnosticImpl {
+  typedef llvm::MallocAllocator Allocator;
+
   InFlightDiagnostic inFlight;
   std::vector<StringRef> textBlobs;
 
@@ -31,8 +33,10 @@ struct BridgedDiagnosticImpl {
 
   ~BridgedDiagnosticImpl() {
     inFlight.flush();
+
+    Allocator allocator;
     for (auto text : textBlobs) {
-      free((void *)text.data());
+      allocator.Deallocate(text.data(), text.size());
     }
   }
 };
@@ -100,8 +104,8 @@ BridgedDiagnostic Diagnostic_create(BridgedDiagnosticEngine cDiags,
                                     BridgedSourceLoc cLoc,
                                     BridgedString cText) {
   StringRef origText = convertString(cText);
-  llvm::MallocAllocator mallocAlloc;
-  StringRef text = origText.copy(mallocAlloc);
+  BridgedDiagnosticImpl::Allocator alloc;
+  StringRef text = origText.copy(alloc);
 
   SourceLoc loc = convertSourceLoc(cLoc);
 
@@ -148,8 +152,8 @@ void Diagnostic_fixItReplace(BridgedDiagnostic cDiag,
   SourceLoc endLoc = convertSourceLoc(cEndLoc);
 
   StringRef origReplaceText = convertString(cReplaceText);
-  llvm::MallocAllocator mallocAlloc;
-  StringRef replaceText = origReplaceText.copy(mallocAlloc);
+  BridgedDiagnosticImpl::Allocator alloc;
+  StringRef replaceText = origReplaceText.copy(alloc);
 
   BridgedDiagnosticImpl *diag = convertDiagnostic(cDiag);
   diag->textBlobs.push_back(replaceText);
diff --git a/lib/ASTGen/Sources/ASTGen/Macros.swift b/lib/ASTGen/Sources/ASTGen/Macros.swift
index 96205f1d149e9..39d623207e286 100644
--- a/lib/ASTGen/Sources/ASTGen/Macros.swift
+++ b/lib/ASTGen/Sources/ASTGen/Macros.swift
@@ -170,6 +170,11 @@ func allocateUTF8String(
   }
 }
 
+@_cdecl("swift_ASTGen_freeString")
+public func freeString(pointer: UnsafePointer<UInt8>?) {
+  pointer?.deallocate()
+}
+
 /// Diagnostics produced here.
 enum ASTGenMacroDiagnostic: DiagnosticMessage, FixItMessage {
   case thrownError(Error)
@@ -413,6 +418,14 @@ 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/Sema/TypeCheckMacros.cpp b/lib/Sema/TypeCheckMacros.cpp
index b25177e43cd8d..c73a6b5c6a374 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) {
@@ -1065,7 +1070,7 @@ 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);
@@ -1343,7 +1348,7 @@ 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);