From 9eb0a097109c5b6e7ccac010d9bd7e5e2129c041 Mon Sep 17 00:00:00 2001
From: Hans Wennborg <hans@hanshq.net>
Date: Thu, 30 Oct 2014 23:10:01 +0000
Subject: [PATCH] Speculative fix for Windows build after r220932

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220936 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Support/Windows/Threading.inc | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/Support/Windows/Threading.inc b/lib/Support/Windows/Threading.inc
index 099c6b28bf6..41fdd981fd6 100644
--- a/lib/Support/Windows/Threading.inc
+++ b/lib/Support/Windows/Threading.inc
@@ -1,5 +1,10 @@
 #include <winbase.h>
 
+#ifdef MemoryFence
+// WinNT.h seems to define a MemoryFence macro.
+#undef MemoryFence
+#endif
+
 void llvm::call_once(once_flag &flag, void (*fptr)(void)) {
   while (flag != Done) {
     if (flag == Wait) {