diff --git a/stdlib/public/Platform/CMakeLists.txt b/stdlib/public/Platform/CMakeLists.txt
index c7e7bac10925d..a7a60a063d9aa 100644
--- a/stdlib/public/Platform/CMakeLists.txt
+++ b/stdlib/public/Platform/CMakeLists.txt
@@ -119,6 +119,13 @@ foreach(sdk ${SWIFT_SDKS})
       list(APPEND glibc_modulemap_target_list ${copy_glibc_modulemap_static})
     endif()
 
+    set(glibc_header_out "${module_dir}/SwiftGlibc.h")
+    handle_gyb_source_single(glibc_header_target
+        SOURCE "SwiftGlibc.h.gyb"
+        OUTPUT "${glibc_header_out}"
+        FLAGS "-DCMAKE_SDK=${sdk}")
+    list(APPEND glibc_modulemap_target_list ${glibc_header_target})
+
     # If this SDK is a target for a non-native host, except if it's for Android
     # with its own native sysroot, create a native modulemap without a sysroot
     # prefix. This is the one we'll install instead.
@@ -150,11 +157,17 @@ foreach(sdk ${SWIFT_SDKS})
     swift_install_in_component(FILES "${glibc_modulemap_out}"
                                DESTINATION "lib/swift/${arch_subdir}"
                                COMPONENT sdk-overlay)
+    swift_install_in_component(FILES "${glibc_header_out}"
+                               DESTINATION "lib/swift/${arch_subdir}"
+                               COMPONENT sdk-overlay)
 
     if(SWIFT_BUILD_STATIC_STDLIB)
       swift_install_in_component(FILES "${glibc_modulemap_out}"
                                  DESTINATION "lib/swift_static/${arch_subdir}"
                                  COMPONENT sdk-overlay)
+      swift_install_in_component(FILES "${glibc_header_out}"
+                                 DESTINATION "lib/swift_static/${arch_subdir}"
+                                 COMPONENT sdk-overlay)
     endif()
   endforeach()
 endforeach()
diff --git a/stdlib/public/Platform/SwiftGlibc.h.gyb b/stdlib/public/Platform/SwiftGlibc.h.gyb
new file mode 100644
index 0000000000000..3391eaee29934
--- /dev/null
+++ b/stdlib/public/Platform/SwiftGlibc.h.gyb
@@ -0,0 +1,107 @@
+%{
+headers = [
+  'stdc-predef.h',
+  'features.h',
+
+  # C standard library
+  'complex.h',
+  'ctype.h',
+  'errno.h',
+  'fenv.h',
+  'float.h',
+  'inttypes.h',
+  'iso646.h',
+  'libutil.h',
+  'limits.h',
+  'locale.h',
+  'math.h',
+  'pty.h',
+  'setjmp.h',
+  'signal.h',
+  'stdarg.h',
+  'stdbool.h',
+  'stddef.h',
+  'stdint.h',
+  'stdio.h',
+  'stdlib.h',
+  'string.h',
+  'tgmath.h',
+  'time.h',
+  'utmp.h',
+  'utmpx.h',
+
+  # POSIX
+  'aio.h',
+  'arpa/inet.h',
+  'bsd/ifaddrs.h',
+  'bsd/pty.h',
+  'cpio.h',
+  'dirent.h',
+  'dlfcn.h',
+  'fcntl.h',
+  'fmtmsg.h',
+  'fnmatch.h',
+  'ftw.h',
+  'glob.h',
+  'grp.h',
+  'iconv.h',
+  'ifaddrs.h',
+  'langinfo.h',
+  'libgen.h',
+  'link.h',
+  'monetary.h',
+  'net/if.h',
+  'netdb.h',
+  'netinet/in.h',
+  'netinet/tcp.h',
+  'nl_types.h',
+  'poll.h',
+  'pthread.h',
+  'pwd.h',
+  'regex.h',
+  'sched.h',
+  'search.h',
+  'semaphore.h',
+  'spawn.h',
+  'strings.h',
+  'sys/event.h',
+  'sys/file.h',
+  'sys/inotify.h',
+  'sys/ioctl.h',
+  'sys/ipc.h',
+  'sys/mman.h',
+  'sys/msg.h',
+  'sys/resource.h',
+  'sys/select.h',
+  'sys/sem.h',
+  'sys/sendfile.h',
+  'sys/shm.h',
+  'sys/socket.h',
+  'sys/stat.h',
+  'sys/statvfs.h',
+  'sys/time.h',
+  'sys/times.h',
+  'sys/types.h',
+  'sys/uio.h',
+  'sys/un.h',
+  'sys/user.h',
+  'sys/utsname.h',
+  'sys/wait.h',
+  'sysexits.h',
+  'syslog.h',
+  'tar.h',
+  'termios.h',
+  'ulimit.h',
+  'unistd.h',
+  'utime.h',
+  'utmpx.h',
+  'wait.h',
+  'wordexp.h',
+]
+}%
+
+% for header in headers:
+#if __has_include(<${header}>)
+#include <${header}>
+#endif
+% end
diff --git a/stdlib/public/Platform/glibc.modulemap.gyb b/stdlib/public/Platform/glibc.modulemap.gyb
index 9a88a108c74c3..455dd111e2ce3 100644
--- a/stdlib/public/Platform/glibc.modulemap.gyb
+++ b/stdlib/public/Platform/glibc.modulemap.gyb
@@ -19,6 +19,9 @@
 /// It's not named just Glibc so that it doesn't conflict in the event of a
 /// future official glibc modulemap.
 module SwiftGlibc [system] {
+% if CMAKE_SDK == "LINUX":
+      link "m"
+% end
 % if CMAKE_SDK in ["LINUX", "FREEBSD", "CYGWIN"]:
   link "pthread"
   // FIXME: util contains rarely used functions and not usually needed. Unfortunately
@@ -36,506 +39,8 @@ module SwiftGlibc [system] {
   link "execinfo"
 % end
 
-  // C standard library
-  module C {
-% if CMAKE_SDK in ["LINUX", "CYGWIN"]:
-    module features {
-% if CMAKE_SDK == "LINUX":
-      header "${GLIBC_INCLUDE_PATH}/stdc-predef.h"
-% end
-      header "${GLIBC_INCLUDE_PATH}/features.h"
-      export *
-    }
-% end
-% if CMAKE_SDK in ["LINUX", "FREEBSD", "CYGWIN", "HAIKU"]:
-    module complex {
-      header "${GLIBC_INCLUDE_PATH}/complex.h"
-      export *
-    }
-% end
-% if CMAKE_SDK in ["LINUX", "CYGWIN"]:
-    module pty {
-      header "${GLIBC_INCLUDE_PATH}/pty.h"
-      export *
-    }
-    module utmp {
-      header "${GLIBC_INCLUDE_PATH}/utmp.h"
-      export *
-    }
-% end
-% if CMAKE_SDK == "FREEBSD":
-    module pty {
-      header "${GLIBC_INCLUDE_PATH}/libutil.h"
-      export *
-    }
-    module utmp {
-      header "${GLIBC_INCLUDE_PATH}/utmpx.h"
-      export *
-    }
-% end
-% if CMAKE_SDK == "HAIKU":
-    module pty {
-      header "${GLIBC_INCLUDE_PATH}/../bsd/pty.h"
-      export *
-    }
-% end
-
-    module ctype {
-      header "${GLIBC_INCLUDE_PATH}/ctype.h"
-      export *
-    }
-    module errno {
-      header "${GLIBC_INCLUDE_PATH}/errno.h"
-      export *
-    }
-
-    module fenv {
-      header "${GLIBC_INCLUDE_PATH}/fenv.h"
-      export *
-    }
-
-    // note: supplied by compiler
-    // module float {
-    //   header "${GLIBC_INCLUDE_PATH}/float.h"
-    //   export *
-    // }
-
-    module inttypes {
-      header "${GLIBC_INCLUDE_PATH}/inttypes.h"
-      export *
-    }
-
-    // note: potentially supplied by compiler
-    // module iso646 {
-    //   header "${GLIBC_INCLUDE_PATH}/iso646.h"
-    //   export *
-    // }
-    // module limits {
-    //   header "${GLIBC_INCLUDE_PATH}/limits.h"
-    //   export *
-    // }
-
-    module locale {
-      header "${GLIBC_INCLUDE_PATH}/locale.h"
-      export *
-    }
-    module math {
-% if CMAKE_SDK == "LINUX":
-      link "m"
-% end
-      header "${GLIBC_INCLUDE_PATH}/math.h"
-      export *
-    }
-% if CMAKE_SDK != "WASI":
-    module setjmp {
-      header "${GLIBC_INCLUDE_PATH}/setjmp.h"
-      export *
-    }
-% end
-    module signal {
-      header "${GLIBC_INCLUDE_PATH}/signal.h"
-      export *
-    }
-
-    // note: supplied by the compiler
-    // module stdarg {
-    //   header "${GLIBC_INCLUDE_PATH}/stdarg.h"
-    //   export *
-    // }
-    // module stdbool {
-    //   header "${GLIBC_INCLUDE_PATH}/stdbool.h"
-    //   export *
-    // }
-    // module stddef {
-    //   header "${GLIBC_INCLUDE_PATH}/stddef.h"
-    //   export *
-    // }
-    // module stdint {
-    //   header "${GLIBC_INCLUDE_PATH}/stdint.h"
-    //   export *
-    // }
-
-    module stdio {
-      header "${GLIBC_INCLUDE_PATH}/stdio.h"
-      export *
-    }
-    module stdlib {
-      header "${GLIBC_INCLUDE_PATH}/stdlib.h"
-      export *
-      export stddef
-    }
-    module string {
-      header "${GLIBC_INCLUDE_PATH}/string.h"
-      export *
-    }
-
-    // note: supplied by the compiler
-    // explicit module tgmath {
-    //   header "${GLIBC_INCLUDE_PATH}/tgmath.h"
-    //   export *
-    // }
-
-    module time {
-      header "${GLIBC_INCLUDE_PATH}/time.h"
-      export *
-    }
-  }
-
-  // POSIX
-  module POSIX {
-% if CMAKE_SDK in ["LINUX", "CYGWIN"]:
-    module wait {
-      header "${GLIBC_INCLUDE_PATH}/wait.h"
-      export *
-    }
-% end
-
-% if CMAKE_SDK in ["LINUX", "FREEBSD"]:
-    module aio {
-      header "${GLIBC_INCLUDE_PATH}/aio.h"
-      export *
-    }
-    module cpio {
-      header "${GLIBC_INCLUDE_PATH}/cpio.h"
-      export *
-    }
-    module fmtmsg {
-      header "${GLIBC_INCLUDE_PATH}/fmtmsg.h"
-      export *
-    }
-    module nl_types {
-      header "${GLIBC_INCLUDE_PATH}/nl_types.h"
-      export *
-    }
-    module ulimit {
-      header "${GLIBC_INCLUDE_PATH}/ulimit.h"
-      export *
-    }
-% end
-
-% if CMAKE_SDK in ["LINUX", "FREEBSD", "CYGWIN"]:
-    module ftw {
-      header "${GLIBC_INCLUDE_PATH}/ftw.h"
-      export *
-    }
-    module glob {
-      header "${GLIBC_INCLUDE_PATH}/glob.h"
-      export *
-    }
-    module iconv {
-      header "${GLIBC_INCLUDE_PATH}/iconv.h"
-      export *
-    }
-    module langinfo {
-      header "${GLIBC_INCLUDE_PATH}/langinfo.h"
-      export *
-    }
-    module monetary {
-      header "${GLIBC_INCLUDE_PATH}/monetary.h"
-      export *
-    }
-    module netdb {
-      header "${GLIBC_INCLUDE_PATH}/netdb.h"
-      export *
-    }
-    module ifaddrs {
-      header "${GLIBC_INCLUDE_PATH}/ifaddrs.h"
-      export *
-    }
-    module search {
-      header "${GLIBC_INCLUDE_PATH}/search.h"
-      export *
-    }
-    module spawn {
-      header "${GLIBC_INCLUDE_PATH}/spawn.h"
-      export *
-    }
-    module syslog {
-      header "${GLIBC_INCLUDE_PATH}/syslog.h"
-      export *
-    }
-    module tar {
-      header "${GLIBC_INCLUDE_PATH}/tar.h"
-      export *
-    }
-    module utmpx {
-      header "${GLIBC_INCLUDE_PATH}/utmpx.h"
-      export *
-    }
-    module wordexp {
-      header "${GLIBC_INCLUDE_PATH}/wordexp.h"
-      export *
-    }
-% end
-
-% if CMAKE_SDK == "HAIKU":
-    module ftw {
-      header "${GLIBC_INCLUDE_PATH}/ftw.h"
-      export *
-    }
-    module glob {
-      header "${GLIBC_INCLUDE_PATH}/glob.h"
-      export *
-    }
-    module iconv {
-      header "${GLIBC_INCLUDE_PATH}/../iconv.h"
-      export *
-    }
-    module langinfo {
-      header "${GLIBC_INCLUDE_PATH}/langinfo.h"
-      export *
-    }
-    module monetary {
-      header "${GLIBC_INCLUDE_PATH}/monetary.h"
-      export *
-    }
-    module netdb {
-      header "${GLIBC_INCLUDE_PATH}/netdb.h"
-      export *
-    }
-    module ifaddrs {
-      header "${GLIBC_INCLUDE_PATH}/../bsd/ifaddrs.h"
-      export *
-    }
-    module search {
-      header "${GLIBC_INCLUDE_PATH}/search.h"
-      export *
-    }
-    module syslog {
-      header "${GLIBC_INCLUDE_PATH}/syslog.h"
-      export *
-    }
-    module tar {
-      header "${GLIBC_INCLUDE_PATH}/tar.h"
-      export *
-    }
-% end
-    module arpa {
-      module inet {
-        header "${GLIBC_INCLUDE_PATH}/arpa/inet.h"
-        export *
-      }
-      export *
-    }
-    module dirent {
-      header "${GLIBC_INCLUDE_PATH}/dirent.h"
-      export *
-    }
-% if CMAKE_SDK != "WASI":
-    module dl {
-      header "${GLIBC_INCLUDE_PATH}/link.h"
-      export *
-    }
-    module dlfcn {
-      header "${GLIBC_INCLUDE_PATH}/dlfcn.h"
-      export *
-    }
-% end
-    module fcntl {
-      header "${GLIBC_INCLUDE_PATH}/fcntl.h"
-      export *
-    }
-    module fnmatch {
-      header "${GLIBC_INCLUDE_PATH}/fnmatch.h"
-      export *
-    }
-% if CMAKE_SDK != "WASI":
-    module grp {
-      header "${GLIBC_INCLUDE_PATH}/grp.h"
-      export *
-    }
-% end
-    module ioctl {
-      header "${GLIBC_ARCH_INCLUDE_PATH}/sys/ioctl.h"
-      export *
-    }
-    module libgen {
-      header "${GLIBC_INCLUDE_PATH}/libgen.h"
-      export *
-    }
-% if CMAKE_SDK != "WASI":
-    module net {
-      module if {
-        header "${GLIBC_INCLUDE_PATH}/net/if.h"
-        export *
-      }
-    }
-% end
-    module netinet {
-      module in {
-        header "${GLIBC_INCLUDE_PATH}/netinet/in.h"
-        export *
-
-        exclude header "${GLIBC_INCLUDE_PATH}/netinet6/in6.h"
-      }
-      module tcp {
-        header "${GLIBC_INCLUDE_PATH}/netinet/tcp.h"
-        export *
-      }
-    }
-    module poll {
-      header "${GLIBC_INCLUDE_PATH}/poll.h"
-      export *
-    }
-% if CMAKE_SDK != "WASI":
-    module pthread {
-      header "${GLIBC_INCLUDE_PATH}/pthread.h"
-      export *
-    }
-% end
-    module pwd {
-      header "${GLIBC_INCLUDE_PATH}/pwd.h"
-      export *
-    }
-    module regex {
-      header "${GLIBC_INCLUDE_PATH}/regex.h"
-      export *
-    }
-    module sched {
-      header "${GLIBC_INCLUDE_PATH}/sched.h"
-      export *
-    }
-    module semaphore {
-      header "${GLIBC_INCLUDE_PATH}/semaphore.h"
-      export *
-    }
-    module strings {
-      header "${GLIBC_INCLUDE_PATH}/strings.h"
-      export *
-    }
-
-    module sys {
-      export *
-
-% if CMAKE_SDK in ["LINUX", "FREEBSD", "CYGWIN", "HAIKU"]:
-      module file {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/file.h"
-        export *
-      }
-      module sem {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/sem.h"
-        export *
-      }
-% if CMAKE_SDK != "HAIKU":
-      module shm {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/shm.h"
-        export *
-      }
-      module inotify {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/inotify.h"
-        export *
-      }
-% end
-      module statvfs {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/statvfs.h"
-        export *
-      }
-% end
-
-% if CMAKE_SDK != "WASI":
-      module ipc {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/ipc.h"
-        export *
-      }
-% end
-      module mman {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/mman.h"
-        export *
-      }
-% if CMAKE_SDK != "WASI":
-      module msg {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/msg.h"
-        export *
-      }
-% end
-      module resource {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/resource.h"
-        export *
-      }
-      module select {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/select.h"
-        export *
-      }
-% if CMAKE_SDK != "FREEBSD" and CMAKE_SDK != "HAIKU" and CMAKE_SDK != "WASI":
-      module sendfile {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/sendfile.h"
-        export *
-      }
-% end
-      module socket {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/socket.h"
-        export *
-      }
-      module stat {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/stat.h"
-        export *
-      }
-      module time {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/time.h"
-        export *
-      }
-      module times {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/times.h"
-        export *
-      }
-      module types {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/types.h"
-        export *
-      }
-% if CMAKE_SDK in ["FREEBSD"]:
-      module event {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/event.h"
-        export *
-      }
-% end
-      module uio {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/uio.h"
-        export *
-      }
-      module un {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/un.h"
-        export *
-      }
-% if CMAKE_SDK in ["LINUX"]:
-      module user {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/user.h"
-        export *
-      }
-% end
-      module utsname {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/utsname.h"
-        export *
-      }
-% if CMAKE_SDK != "WASI":
-      module wait {
-        header "${GLIBC_ARCH_INCLUDE_PATH}/sys/wait.h"
-        export *
-      }
-    }
-% end
-% if CMAKE_SDK in ["LINUX", "FREEBSD"]:
-    module sysexits {
-      header "${GLIBC_INCLUDE_PATH}/sysexits.h"
-      export *
-    }
-% end
-% if CMAKE_SDK != "WASI":
-    module termios {
-      header "${GLIBC_INCLUDE_PATH}/termios.h"
-      export *
-    }
-% end
-    module unistd {
-      header "${GLIBC_INCLUDE_PATH}/unistd.h"
-      export *
-    }
-% if CMAKE_SDK != "WASI":
-    module utime {
-      header "${GLIBC_INCLUDE_PATH}/utime.h"
-      export *
-    }
-  }
-% end
+  header "SwiftGlibc.h"
+  export *
 }
 
 % if CMAKE_SDK != "WASI":
diff --git a/test/Interop/C/libc/Inputs/include-signal.h b/test/Interop/C/libc/Inputs/include-signal.h
new file mode 100644
index 0000000000000..019db1a7f5097
--- /dev/null
+++ b/test/Interop/C/libc/Inputs/include-signal.h
@@ -0,0 +1,8 @@
+#ifndef TEST_INTEROP_C_LIBC_INPUTS_INCLUDE_SIGNAL_H
+#define TEST_INTEROP_C_LIBC_INPUTS_INCLUDE_SIGNAL_H
+
+#include <signal.h>
+
+pid_t returnPidT();
+
+#endif // TEST_INTEROP_C_LIBC_INPUTS_INCLUDE_SIGNAL_H
\ No newline at end of file
diff --git a/test/Interop/C/libc/Inputs/module.modulemap b/test/Interop/C/libc/Inputs/module.modulemap
new file mode 100644
index 0000000000000..566cb2144e560
--- /dev/null
+++ b/test/Interop/C/libc/Inputs/module.modulemap
@@ -0,0 +1,3 @@
+module IncludeSignal {
+  header "include-signal.h"
+}
diff --git a/test/Interop/C/libc/include-signal.swift b/test/Interop/C/libc/include-signal.swift
new file mode 100644
index 0000000000000..3b420364f3ce8
--- /dev/null
+++ b/test/Interop/C/libc/include-signal.swift
@@ -0,0 +1,33 @@
+// RUN: %target-typecheck-verify-swift -I %S/Inputs
+
+// Some types such as pid_t that glibc defines are defined using the following
+// construct:
+//
+// #ifndef __pid_t_defined
+// typedef __pid_t pid_t;
+// #define __pid_t_defined
+// #endif
+//
+// glibc defines pid_t in this way in multiple header files, as required by
+// POSIX (e.g. signal.h, unistd.h, and sys/types.h). A number of other types
+// use the same construct (e.g. ssize_t, intptr_t, uid_t, gid_t).
+//
+// Because Swift does not set the -fmodules-local-submodule-visibility flag,
+// the __pid_t_defined macro can leak from the first submodule that defines it
+// into all submodules that follow.
+//
+// As a consequence, a C header file may fail to compile when imported into
+// Swift, even though it compiles cleanly outside Swift with the same system
+// headers.
+//
+// This is a regression test for a bug that was once present in SwiftGlibc
+// module layout. Originally SwiftGlibc defined one submodule per header, and
+// types such as pid_t were defined by the first module that encountered the
+// ifndef construct.
+//
+// See https://forums.swift.org/t/problems-with-swiftglibc-and-proposed-fix/37594
+// for further details.
+
+// REQUIRES: OS=linux-gnu
+
+import IncludeSignal
\ No newline at end of file
diff --git a/test/Interop/Cxx/libc/include-glibc.swift b/test/Interop/Cxx/libc/include-glibc.swift
new file mode 100644
index 0000000000000..116dc88895783
--- /dev/null
+++ b/test/Interop/Cxx/libc/include-glibc.swift
@@ -0,0 +1,15 @@
+// RUN: %target-run-simple-swift(-Xfrontend -enable-cxx-interop)
+
+// REQUIRES: executable_test
+// REQUIRES: OS=linux-gnu
+
+import Glibc
+import StdlibUnittest
+
+var GlibcTests = TestSuite("GlibcTests")
+
+GlibcTests.test("abs") {
+  expectEqual(42, abs(-42))
+}
+
+runAllTests()