diff --git a/clang/lib/Headers/lzcntintrin.h b/clang/lib/Headers/lzcntintrin.h
index 5bb74355047f..35d6659d245b 100644
--- a/clang/lib/Headers/lzcntintrin.h
+++ b/clang/lib/Headers/lzcntintrin.h
@@ -44,12 +44,24 @@ __lzcnt32(unsigned int __X)
   return __X ? __builtin_clz(__X) : 32;
 }
 
+static __inline__ unsigned int __attribute__((__always_inline__, __nodebug__))
+_lzcnt_u32(unsigned int __X)
+{
+  return __X ? __builtin_clz(__X) : 32;
+}
+
 #ifdef __x86_64__
 static __inline__ unsigned long long __attribute__((__always_inline__, __nodebug__))
 __lzcnt64(unsigned long long __X)
 {
   return __X ? __builtin_clzll(__X) : 64;
 }
+
+static __inline__ unsigned long long __attribute__((__always_inline__, __nodebug__))
+_lzcnt_u64(unsigned long long __X)
+{
+  return __X ? __builtin_clzll(__X) : 64;
+}
 #endif
 
 #endif /* __LZCNTINTRIN_H */
diff --git a/clang/test/CodeGen/lzcnt-builtins.c b/clang/test/CodeGen/lzcnt-builtins.c
index a43c4eede452..a083de9d35f0 100644
--- a/clang/test/CodeGen/lzcnt-builtins.c
+++ b/clang/test/CodeGen/lzcnt-builtins.c
@@ -22,3 +22,15 @@ unsigned long long test__lzcnt64(unsigned long long __X)
   // CHECK: @llvm.ctlz.i64
   return __lzcnt64(__X);
 }
+
+unsigned int test_lzcnt_u32(unsigned int __X)
+{
+  // CHECK: @llvm.ctlz.i32
+  return _lzcnt_u32(__X);
+}
+
+unsigned long long test__lzcnt_u64(unsigned long long __X)
+{
+  // CHECK: @llvm.ctlz.i64
+  return _lzcnt_u64(__X);
+}