diff --git a/include/llvm/Support/Process.h b/include/llvm/Support/Process.h
index bb7467bfc83..861667927d8 100644
--- a/include/llvm/Support/Process.h
+++ b/include/llvm/Support/Process.h
@@ -192,6 +192,15 @@ public:
   // components should not call this.
   static std::error_code FixupStandardFileDescriptors();
 
+  // This function safely closes a file descriptor.  It is not safe to retry
+  // close(2) when it returns with errno equivalent to EINTR; this is because
+  // *nixen cannot agree if the file descriptor is, in fact, closed when this
+  // occurs.
+  //
+  // N.B. Some operating systems, due to thread cancellation, cannot properly
+  // guarantee that it will or will not be closed one way or the other!
+  static std::error_code SafelyCloseFileDescriptor(int FD);
+
   /// This function determines if the standard input is connected directly
   /// to a user's input (keyboard probably), rather than coming from a file
   /// or pipe.
diff --git a/lib/Support/Unix/Process.inc b/lib/Support/Unix/Process.inc
index 01c78cbc0da..d39443b1124 100644
--- a/lib/Support/Unix/Process.inc
+++ b/lib/Support/Unix/Process.inc
@@ -258,6 +258,30 @@ std::error_code Process::FixupStandardFileDescriptors() {
   return std::error_code();
 }
 
+std::error_code Process::SafelyCloseFileDescriptor(int FD) {
+  // Create a signal set filled with *all* signals.
+  sigset_t FullSet;
+  if (sigfillset(&FullSet) < 0)
+    return std::error_code(errno, std::generic_category());
+  // Atomically swap our current signal mask with a full mask.
+  sigset_t SavedSet;
+  if (int EC = pthread_sigmask(SIG_SETMASK, &FullSet, &SavedSet))
+    return std::error_code(EC, std::generic_category());
+  // Attempt to close the file descriptor.
+  // We need to save the error, if one occurs, because our subsequent call to
+  // pthread_sigmask might tamper with errno.
+  int ErrnoFromClose = 0;
+  if (::close(FD) < 0)
+    ErrnoFromClose = errno;
+  // Restore the signal mask back to what we saved earlier.
+  int EC = pthread_sigmask(SIG_SETMASK, &SavedSet, nullptr);
+  // The error code from close takes precedence over the one from
+  // pthread_sigmask.
+  if (ErrnoFromClose)
+    return std::error_code(ErrnoFromClose, std::generic_category());
+  return std::error_code(EC, std::generic_category());
+}
+
 bool Process::StandardInIsUserInput() {
   return FileDescriptorIsDisplayed(STDIN_FILENO);
 }
diff --git a/lib/Support/Windows/Process.inc b/lib/Support/Windows/Process.inc
index db87d8ed60e..3819e638c72 100644
--- a/lib/Support/Windows/Process.inc
+++ b/lib/Support/Windows/Process.inc
@@ -277,6 +277,12 @@ std::error_code Process::FixupStandardFileDescriptors() {
   return std::error_code();
 }
 
+std::error_code Process::SafelyCloseFileDescriptor(int FD) {
+  if (::close(FD) < 0)
+    return std::error_code(errno, std::generic_category());
+  return std::error_code();
+}
+
 bool Process::StandardInIsUserInput() {
   return FileDescriptorIsDisplayed(0);
 }
diff --git a/lib/Support/raw_ostream.cpp b/lib/Support/raw_ostream.cpp
index c2c55cff7ed..bbbbe4ae8c6 100644
--- a/lib/Support/raw_ostream.cpp
+++ b/lib/Support/raw_ostream.cpp
@@ -536,12 +536,8 @@ raw_fd_ostream::raw_fd_ostream(int fd, bool shouldClose, bool unbuffered)
 raw_fd_ostream::~raw_fd_ostream() {
   if (FD >= 0) {
     flush();
-    if (ShouldClose)
-      while (::close(FD) != 0)
-        if (errno != EINTR) {
-          error_detected();
-          break;
-        }
+    if (ShouldClose && sys::Process::SafelyCloseFileDescriptor(FD))
+      error_detected();
   }
 
 #ifdef __MINGW32__
@@ -615,11 +611,8 @@ void raw_fd_ostream::close() {
   assert(ShouldClose);
   ShouldClose = false;
   flush();
-  while (::close(FD) != 0)
-    if (errno != EINTR) {
-      error_detected();
-      break;
-    }
+  if (sys::Process::SafelyCloseFileDescriptor(FD))
+    error_detected();
   FD = -1;
 }