Index: include/clang/Basic/BuiltinsX86.def
===================================================================
--- include/clang/Basic/BuiltinsX86.def
+++ include/clang/Basic/BuiltinsX86.def
@@ -1814,6 +1814,9 @@
 TARGET_BUILTIN(__builtin_ia32_monitorx, "vv*UiUi", "", "mwaitx")
 TARGET_BUILTIN(__builtin_ia32_mwaitx, "vUiUiUi", "", "mwaitx")
 
+// CLZERO
+TARGET_BUILTIN(__builtin_ia32_clzero, "vv*", "", "clzero")
+
 // MSVC
 TARGET_HEADER_BUILTIN(_BitScanForward, "UcULi*ULi", "nh", "intrin.h", ALL_MS_LANGUAGES, "")
 TARGET_HEADER_BUILTIN(_BitScanReverse, "UcULi*ULi", "nh", "intrin.h", ALL_MS_LANGUAGES, "")
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -1714,6 +1714,7 @@
 def mno_xsavec : Flag<["-"], "mno-xsavec">, Group<m_x86_Features_Group>;
 def mno_xsaves : Flag<["-"], "mno-xsaves">, Group<m_x86_Features_Group>;
 def mno_mwaitx : Flag<["-"], "mno-mwaitx">, Group<m_x86_Features_Group>;
+def mno_clzero : Flag<["-"], "mno-clzero">, Group<m_x86_Features_Group>;
 def mno_pku : Flag<["-"], "mno-pku">, Group<m_x86_Features_Group>;
 
 def munaligned_access : Flag<["-"], "munaligned-access">, Group<m_arm_Features_Group>,
@@ -1907,6 +1908,7 @@
 def mxsavec : Flag<["-"], "mxsavec">, Group<m_x86_Features_Group>;
 def mxsaves : Flag<["-"], "mxsaves">, Group<m_x86_Features_Group>;
 def mmwaitx : Flag<["-"], "mmwaitx">, Group<m_x86_Features_Group>;
+def mclzero : Flag<["-"], "mclzero">, Group<m_x86_Features_Group>;
 def mips16 : Flag<["-"], "mips16">, Group<m_Group>;
 def mno_mips16 : Flag<["-"], "mno-mips16">, Group<m_Group>;
 def mmicromips : Flag<["-"], "mmicromips">, Group<m_Group>;
Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -2489,6 +2489,7 @@
   bool HasXSAVEC = false;
   bool HasXSAVES = false;
   bool HasMWAITX = false;
+  bool HasCLZERO = false;
   bool HasPKU = false;
   bool HasCLFLUSHOPT = false;
   bool HasPCOMMIT = false;
@@ -3205,6 +3206,7 @@
     setFeatureEnabledImpl(Features, "bmi", true);
     setFeatureEnabledImpl(Features, "bmi2", true);
     setFeatureEnabledImpl(Features, "clflushopt", true);
+    setFeatureEnabledImpl(Features, "clzero", true);
     setFeatureEnabledImpl(Features, "cx16", true);
     setFeatureEnabledImpl(Features, "f16c", true);
     setFeatureEnabledImpl(Features, "fma", true);
@@ -3556,6 +3558,8 @@
       HasXSAVES = true;
     } else if (Feature == "+mwaitx") {
       HasMWAITX = true;
+    } else if (Feature == "+clzero") {
+      HasCLZERO = true;
     } else if (Feature == "+pku") {
       HasPKU = true;
     } else if (Feature == "+clflushopt") {
@@ -3834,6 +3838,9 @@
   if (HasMWAITX)
     Builder.defineMacro("__MWAITX__");
 
+  if (HasCLZERO)
+    Builder.defineMacro("__CLZERO__");
+
   switch (XOPLevel) {
   case XOP:
     Builder.defineMacro("__XOP__");
Index: lib/Headers/CMakeLists.txt
===================================================================
--- lib/Headers/CMakeLists.txt
+++ lib/Headers/CMakeLists.txt
@@ -28,6 +28,7 @@
   __clang_cuda_intrinsics.h
   __clang_cuda_math_forward_declares.h
   __clang_cuda_runtime_wrapper.h
+  clzerointrin.h
   cpuid.h
   clflushoptintrin.h
   emmintrin.h
Index: lib/Headers/clzerointrin.h
===================================================================
--- lib/Headers/clzerointrin.h
+++ lib/Headers/clzerointrin.h
@@ -0,0 +1,72 @@
+/*===----------------------- clzerointrin.h - CLZERO ----------------------===
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ *===-----------------------------------------------------------------------===
+ */
+//===----------------------------------------------------------------------===//
+//====  Copyright (c) 2015 Advanced Micro Devices, Inc.  All rights reserved.
+//
+//               Developed by: Advanced Micro Devices, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// with the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// Redistributions of source code must retain the above copyright notice, this
+// list of conditions and the following disclaimers.
+//
+// Redistributions in binary form must reproduce the above copyright notice,
+// this list of conditions and the following disclaimers in the documentation
+// and/or other materials provided with the distribution.
+//
+// Neither the names of Advanced Micro Devices, Inc., nor the names of its
+// contributors may be used to endorse or promote products derived from this
+// Software without specific prior written permission.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH
+// THE SOFTWARE.
+//===----------------------------------------------------------------------===//
+//
+#ifndef __X86INTRIN_H
+#error "Never use <clzerointrin.h> directly; include <x86intrin.h> instead."
+#endif
+
+#ifndef _CLZEROINTRIN_H
+#define _CLZEROINTRIN_H
+
+/* Define the default attributes for the functions in this file. */
+#define __DEFAULT_FN_ATTRS __attribute__((__always_inline__, __nodebug__,  __target__("clzero")))
+static __inline__ void __DEFAULT_FN_ATTRS
+_mm_clzero (void * __line)
+{
+  __builtin_ia32_clzero ((void *)__line);
+}
+
+#undef __DEFAULT_FN_ATTRS 
+
+#endif /* _CLZEROINTRIN_H */
Index: lib/Headers/module.modulemap
===================================================================
--- lib/Headers/module.modulemap
+++ lib/Headers/module.modulemap
@@ -61,6 +61,7 @@
     textual header "xopintrin.h"
     textual header "fma4intrin.h"
     textual header "mwaitxintrin.h"
+    textual header "clzerointrin.h"
 
     explicit module mm_malloc {
       requires !freestanding
Index: lib/Headers/x86intrin.h
===================================================================
--- lib/Headers/x86intrin.h
+++ lib/Headers/x86intrin.h
@@ -80,6 +80,10 @@
 #include <mwaitxintrin.h>
 #endif
 
+#if !defined(_MSC_VER) || __has_feature(modules) || defined(__CLZERO__)
+#include <clzerointrin.h>
+#endif
+
 /* FIXME: LWP */
 
 #endif /* __X86INTRIN_H */