Index: cmake/config-ix.cmake
===================================================================
--- cmake/config-ix.cmake
+++ cmake/config-ix.cmake
@@ -198,6 +198,7 @@
 check_symbol_exists(strerror_r string.h HAVE_STRERROR_R)
 check_symbol_exists(strerror_s string.h HAVE_DECL_STRERROR_S)
 check_symbol_exists(setenv stdlib.h HAVE_SETENV)
+check_symbol_exists(O_CLOEXEC "sys/types.h;sys/stat.h;fcntl.h" HAVE_O_CLOEXEC)
 if( PURE_WINDOWS )
   check_symbol_exists(_chsize_s io.h HAVE__CHSIZE_S)
 
Index: include/llvm/Config/config.h.cmake
===================================================================
--- include/llvm/Config/config.h.cmake
+++ include/llvm/Config/config.h.cmake
@@ -153,6 +153,9 @@
 /* Define to 1 if you have the <ndir.h> header file, and it defines `DIR'. */
 #cmakedefine HAVE_NDIR_H ${HAVE_NDIR_H}
 
+/* Define to 1 if you have the O_CLOEXEC open(2) flag */
+#cmakedefine HAVE_O_CLOEXEC ${HAVE_O_CLOEXEC}
+
 /* Define to 1 if you have the `posix_fallocate' function. */
 #cmakedefine HAVE_POSIX_FALLOCATE ${HAVE_POSIX_FALLOCATE}
 
Index: include/llvm/Support/FileSystem.h
===================================================================
--- include/llvm/Support/FileSystem.h
+++ include/llvm/Support/FileSystem.h
@@ -638,7 +638,10 @@
   F_Text = 4,
 
   /// Open the file for read and write.
-  F_RW = 8
+  F_RW = 8,
+
+  /// Make the handle inheritable for child processes.
+  F_Inheritable = 16,
 };
 
 inline OpenFlags operator|(OpenFlags A, OpenFlags B) {
Index: lib/Support/Unix/Path.inc
===================================================================
--- lib/Support/Unix/Path.inc
+++ lib/Support/Unix/Path.inc
@@ -629,12 +629,26 @@
   if (Flags & F_Excl)
     OpenFlags |= O_EXCL;
 
+#ifdef HAVE_O_CLOEXEC
+  if (!(Flags & F_Inheritable))
+    OpenFlags |= O_CLOEXEC;
+#endif
+
   SmallString<128> Storage;
   StringRef P = Name.toNullTerminatedStringRef(Storage);
   while ((ResultFD = open(P.begin(), OpenFlags, Mode)) < 0) {
     if (errno != EINTR)
       return std::error_code(errno, std::generic_category());
   }
+
+#ifndef HAVE_O_CLOEXEC
+  if (!(Flags & F_Inheritable)) {
+    int r = fcntl(ResultFD, F_SETFD, FD_CLOEXEC);
+    (void)r;
+    assert(r == 0);
+  }
+#endif
+
   return std::error_code();
 }
 
Index: lib/Support/Windows/Path.inc
===================================================================
--- lib/Support/Windows/Path.inc
+++ lib/Support/Windows/Path.inc
@@ -774,9 +774,14 @@
   if (Flags & F_RW)
     Access |= GENERIC_READ;
 
+  SECURITY_ATTRIBUTES sa;
+  sa.nLength = sizeof sa;
+  sa.lpSecurityDescriptor = nullptr;
+  sa.bInheritHandle = Flags & F_Inheritable ? TRUE : FALSE;
+
   HANDLE H = ::CreateFileW(PathUTF16.begin(), Access,
-                           FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,
-                           CreationDisposition, FILE_ATTRIBUTE_NORMAL, NULL);
+                           FILE_SHARE_READ | FILE_SHARE_WRITE, &sa,
+                           CreationDisposition, FILE_ATTRIBUTE_NORMAL, nullptr);
 
   if (H == INVALID_HANDLE_VALUE) {
     DWORD LastError = ::GetLastError();