1 files changed, 15 insertions, 3 deletions
diff --git a/lib/Headers/lzcntintrin.h b/lib/Headers/lzcntintrin.h
index 62ab5ca2f3580..35d6659d245b8 100644
--- a/lib/Headers/lzcntintrin.h
+++ b/lib/Headers/lzcntintrin.h
@@ -35,20 +35,32 @@
 static __inline__ unsigned short __attribute__((__always_inline__, __nodebug__))
 __lzcnt16(unsigned short __X)
 {
-  return __builtin_clzs(__X);
+  return __X ? __builtin_clzs(__X) : 16;
 }
 
 static __inline__ unsigned int __attribute__((__always_inline__, __nodebug__))
 __lzcnt32(unsigned int __X)
 {
-  return __builtin_clz(__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 __builtin_clzll(__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