Index: lib/Headers/bmiintrin.h
===================================================================
--- lib/Headers/bmiintrin.h
+++ lib/Headers/bmiintrin.h
@@ -281,12 +281,19 @@
 ///    An unsigned 32-bit integer whose trailing zeros are to be counted.
 /// \returns An unsigned 32-bit integer containing the number of trailing zero
 ///    bits in the operand.
+
 static __inline__ unsigned int __RELAXED_FN_ATTRS
 __tzcnt_u32(unsigned int __X)
 {
   return __X ? __builtin_ctz(__X) : 32;
 }
 
+static __inline__ int __RELAXED_FN_ATTRS
+_mm_tzcnt_32(unsigned int __X)
+{
+  return __X ? __builtin_ctz(__X) : 32;
+}
+
 #ifdef __x86_64__
 
 /// \brief Performs a bitwise AND of the second operand with the one's
@@ -502,12 +509,19 @@
 ///    An unsigned 64-bit integer whose trailing zeros are to be counted.
 /// \returns An unsigned 64-bit integer containing the number of trailing zero
 ///    bits in the operand.
+
 static __inline__ unsigned long long __RELAXED_FN_ATTRS
 __tzcnt_u64(unsigned long long __X)
 {
   return __X ? __builtin_ctzll(__X) : 64;
 }
 
+static __inline__ long long __RELAXED_FN_ATTRS
+_mm_tzcnt_64(unsigned long long __X)
+{
+  return __X ? __builtin_ctzll(__X) : 64;
+}
+
 #endif /* __x86_64__ */
 
 #undef __DEFAULT_FN_ATTRS
Index: test/CodeGen/bmi-builtins.c
===================================================================
--- test/CodeGen/bmi-builtins.c
+++ test/CodeGen/bmi-builtins.c
@@ -64,6 +64,13 @@
   return __tzcnt_u32(__X);
 }
 
+int test_mm_tzcnt_32(unsigned int __X) {
+  // CHECK-LABEL: test_mm_tzcnt_32
+  // CHECK: icmp ne i32 %{{.*}}, 0
+  // CHECK: i32 @llvm.cttz.i32(i32 %{{.*}}, i1 true)
+  return _mm_tzcnt_32(__X);
+}
+
 unsigned long long test__andn_u64(unsigned long __X, unsigned long __Y) {
   // CHECK-LABEL: test__andn_u64
   // CHECK: xor i64 %{{.*}}, -1
@@ -105,6 +112,13 @@
   return __tzcnt_u64(__X);
 }
 
+long long test_mm_tzcnt_64(unsigned long long __X) {
+  // CHECK-LABEL: test_mm_tzcnt_64
+  // CHECK: icmp ne i64 %{{.*}}, 0
+  // CHECK: i64 @llvm.cttz.i64(i64 %{{.*}}, i1 true)
+  return _mm_tzcnt_64(__X);
+}
+
 // Intel intrinsics
 
 unsigned short test_tzcnt_u16(unsigned short __X) {