diff --git a/include/llvm/PassSupport.h b/include/llvm/PassSupport.h
index 082790956c4..c50c2cc184e 100644
--- a/include/llvm/PassSupport.h
+++ b/include/llvm/PassSupport.h
@@ -25,6 +25,7 @@
 #include "llvm/PassRegistry.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Support/Atomic.h"
+#include "llvm/Support/Valgrind.h"
 #include <vector>
 
 namespace llvm {
@@ -135,7 +136,10 @@ private:
   if (old_val == 0) { \
     function(Registry); \
     sys::MemoryFence(); \
+    TsanIgnoreWritesBegin(); \
+    TsanHappensBefore(&initialized); \
     initialized = 2; \
+    TsanIgnoreWritesEnd(); \
   } else { \
     sys::cas_flag tmp = initialized; \
     sys::MemoryFence(); \
@@ -143,7 +147,8 @@ private:
       tmp = initialized; \
       sys::MemoryFence(); \
     } \
-  }
+  } \
+  TsanHappensAfter(&initialized);
 
 #define INITIALIZE_PASS(passName, arg, name, cfg, analysis) \
   static void* initialize##passName##PassOnce(PassRegistry &Registry) { \