Index: cfe/trunk/lib/Headers/Intrin.h
===================================================================
--- cfe/trunk/lib/Headers/Intrin.h
+++ cfe/trunk/lib/Headers/Intrin.h
@@ -417,9 +417,18 @@
 #endif
 unsigned __int64 _shlx_u64(unsigned __int64, unsigned int);
 unsigned __int64 shrx_u64(unsigned __int64, unsigned int);
-unsigned __int64 _umul128(unsigned __int64 _Multiplier,
-                          unsigned __int64 _Multiplicand,
-                          unsigned __int64 *_HighProduct);
+/*
+ * Multiply two 64-bit integers and obtain a 64-bit result.
+ * The low-half is returned directly and the high half is in an out parameter.
+ */
+static __inline__ unsigned __int64 __attribute__((__always_inline__, __nodebug__))
+_umul128(unsigned __int64 _Multiplier, unsigned __int64 _Multiplicand,
+         unsigned __int64 *_HighProduct) {
+  unsigned __int128 _FullProduct =
+      (unsigned __int128)_Multiplier * (unsigned __int128)_Multiplicand;
+  *_HighProduct = FullProduct >> 64;
+  return FullProduct;
+}
 void __cdecl _xrstor64(void const *, unsigned __int64);
 void __cdecl _xsave64(void *, unsigned __int64);
 void __cdecl _xsaveopt64(void *, unsigned __int64);