diff --git a/include/llvm/Support/MathExtras.h b/include/llvm/Support/MathExtras.h
index 340b7741b1b..190df1f05eb 100644
--- a/include/llvm/Support/MathExtras.h
+++ b/include/llvm/Support/MathExtras.h
@@ -315,8 +315,6 @@ inline unsigned CountPopulation_32(uint32_t Value) {
 inline unsigned CountPopulation_64(uint64_t Value) {
 #if __GNUC__ >= 4
   return __builtin_popcountll(Value);
-#elif defined(_MSC_VER) && defined(_M_X64)
-  return __popcnt64(Value);
 #else
   uint64_t v = Value - ((Value >> 1) & 0x5555555555555555ULL);
   v = (v & 0x3333333333333333ULL) + ((v >> 2) & 0x3333333333333333ULL);