Index: cfe/trunk/include/clang/Basic/BuiltinsX86.def
===================================================================
--- cfe/trunk/include/clang/Basic/BuiltinsX86.def
+++ cfe/trunk/include/clang/Basic/BuiltinsX86.def
@@ -2272,5 +2272,9 @@
 TARGET_BUILTIN(__builtin_ia32_cvtusi2ss32, "V4fV4fUiIi","","avx512f")
 TARGET_BUILTIN(__builtin_ia32_cvtusi2ss64, "V4fV4fULLiIi","","avx512f")
 
+// MONITORX/MWAITX
+TARGET_BUILTIN(__builtin_ia32_monitorx, "vv*UiUi", "", "mwaitx")
+TARGET_BUILTIN(__builtin_ia32_mwaitx, "vUiUiUi", "", "mwaitx")
+
 #undef BUILTIN
 #undef TARGET_BUILTIN
Index: cfe/trunk/include/clang/Driver/Options.td
===================================================================
--- cfe/trunk/include/clang/Driver/Options.td
+++ cfe/trunk/include/clang/Driver/Options.td
@@ -1425,6 +1425,7 @@
 def mno_xsaveopt : Flag<["-"], "mno-xsaveopt">, Group<m_x86_Features_Group>;
 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_pku : Flag<["-"], "mno-pku">, Group<m_x86_Features_Group>;
 
 def munaligned_access : Flag<["-"], "munaligned-access">, Group<m_arm_Features_Group>,
@@ -1610,6 +1611,7 @@
 def mxsaveopt : Flag<["-"], "mxsaveopt">, Group<m_x86_Features_Group>;
 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 mips16 : Flag<["-"], "mips16">, Group<m_Group>;
 def mno_mips16 : Flag<["-"], "mno-mips16">, Group<m_Group>;
 def mmicromips : Flag<["-"], "mmicromips">, Group<m_Group>;
Index: cfe/trunk/lib/Basic/Targets.cpp
===================================================================
--- cfe/trunk/lib/Basic/Targets.cpp
+++ cfe/trunk/lib/Basic/Targets.cpp
@@ -2273,6 +2273,7 @@
   bool HasXSAVEOPT = false;
   bool HasXSAVEC = false;
   bool HasXSAVES = false;
+  bool HasMWAITX = false;
   bool HasPKU = false;
   bool HasCLFLUSHOPT = false;
   bool HasPCOMMIT = false;
@@ -2947,6 +2948,7 @@
   case CK_BDVER4:
     setFeatureEnabledImpl(Features, "avx2", true);
     setFeatureEnabledImpl(Features, "bmi2", true);
+    setFeatureEnabledImpl(Features, "mwaitx", true);
     // FALLTHROUGH
   case CK_BDVER3:
     setFeatureEnabledImpl(Features, "fsgsbase", true);
@@ -3266,6 +3268,8 @@
       HasXSAVEC = true;
     } else if (Feature == "+xsaves") {
       HasXSAVES = true;
+    } else if (Feature == "+mwaitx") {
+      HasMWAITX = true;
     } else if (Feature == "+pku") {
       HasPKU = true;
     } else if (Feature == "+clflushopt") {
@@ -3538,6 +3542,9 @@
   if (HasTBM)
     Builder.defineMacro("__TBM__");
 
+  if (HasMWAITX)
+    Builder.defineMacro("__MWAITX__");
+
   switch (XOPLevel) {
   case XOP:
     Builder.defineMacro("__XOP__");
Index: cfe/trunk/lib/Headers/CMakeLists.txt
===================================================================
--- cfe/trunk/lib/Headers/CMakeLists.txt
+++ cfe/trunk/lib/Headers/CMakeLists.txt
@@ -78,6 +78,7 @@
   xsaveoptintrin.h
   xsavecintrin.h
   xsavesintrin.h
+  mwaitxintrin.h
   xtestintrin.h
   avx512ifmaintrin.h
   avx512ifmavlintrin.h
Index: cfe/trunk/lib/Headers/module.modulemap
===================================================================
--- cfe/trunk/lib/Headers/module.modulemap
+++ cfe/trunk/lib/Headers/module.modulemap
@@ -125,6 +125,10 @@
       export pclmul
     }
 
+    explicit module mwaitx {
+      header "mwaitxintrin.h"
+    }
+
     explicit module aes {
       header "__wmmintrin_aes.h"
     }
Index: cfe/trunk/lib/Headers/mwaitxintrin.h
===================================================================
--- cfe/trunk/lib/Headers/mwaitxintrin.h
+++ cfe/trunk/lib/Headers/mwaitxintrin.h
@@ -0,0 +1,47 @@
+/*===---- mwaitxintrin.h - MONITORX/MWAITX intrinsics ----------------------===
+ *
+ * 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.
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#ifndef __X86INTRIN_H
+#error "Never use <mwaitxintrin.h> directly; include <x86intrin.h> instead."
+#endif
+
+#ifndef _MWAITXINTRIN_H
+#define _MWAITXINTRIN_H
+
+/* Define the default attributes for the functions in this file. */
+#define __DEFAULT_FN_ATTRS __attribute__((__always_inline__, __nodebug__,  __target__("mwaitx")))
+static __inline__ void __DEFAULT_FN_ATTRS
+_mm_monitorx(void const * __p, unsigned __extensions, unsigned __hints)
+{
+  __builtin_ia32_monitorx((void *)__p, __extensions, __hints);
+}
+
+static __inline__ void __DEFAULT_FN_ATTRS
+_mm_mwaitx(unsigned __extensions, unsigned __hints, unsigned __clock)
+{
+  __builtin_ia32_mwaitx(__extensions, __hints, __clock);
+}
+
+#undef __DEFAULT_FN_ATTRS 
+
+#endif /* _MWAITXINTRIN_H */
Index: cfe/trunk/lib/Headers/x86intrin.h
===================================================================
--- cfe/trunk/lib/Headers/x86intrin.h
+++ cfe/trunk/lib/Headers/x86intrin.h
@@ -76,6 +76,10 @@
 #include <f16cintrin.h>
 #endif
 
+#if !defined(_MSC_VER) || __has_feature(modules) || defined(__MWAITX__)
+#include <mwaitxintrin.h>
+#endif
+
 /* FIXME: LWP */
 
 #endif /* __X86INTRIN_H */
Index: cfe/trunk/test/CodeGen/builtins-x86.c
===================================================================
--- cfe/trunk/test/CodeGen/builtins-x86.c
+++ cfe/trunk/test/CodeGen/builtins-x86.c
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -DUSE_64 -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -emit-llvm -o %t %s
-// RUN: %clang_cc1 -DUSE_ALL -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -fsyntax-only -o %t %s
+// RUN: %clang_cc1 -DUSE_64 -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -emit-llvm -o %t %s
+// RUN: %clang_cc1 -DUSE_ALL -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -fsyntax-only -o %t %s
 
 #ifdef USE_ALL
 #define USE_3DNOW
@@ -281,6 +281,9 @@
   (void)__builtin_ia32_xsaves(tmp_vp, tmp_ULLi);
   (void)__builtin_ia32_xsaves64(tmp_vp, tmp_ULLi);
 
+  (void) __builtin_ia32_monitorx(tmp_vp, tmp_Ui, tmp_Ui);
+  (void) __builtin_ia32_mwaitx(tmp_Ui, tmp_Ui, tmp_Ui);
+
   tmp_V4f = __builtin_ia32_cvtpi2ps(tmp_V4f, tmp_V2i);
   tmp_V2i = __builtin_ia32_cvtps2pi(tmp_V4f);
   tmp_i = __builtin_ia32_cvtss2si(tmp_V4f);