diff --git a/include/clang/Basic/BuiltinsX86.def b/include/clang/Basic/BuiltinsX86.def
index 62ebec2..5498ccf 100644
--- a/include/clang/Basic/BuiltinsX86.def
+++ b/include/clang/Basic/BuiltinsX86.def
@@ -596,4 +596,10 @@
 BUILTIN(__builtin_ia32_psrlv4di, "V4LLiV4LLiV4LLi", "")
 BUILTIN(__builtin_ia32_psrlv2di, "V2LLiV2LLiV2LLi", "")
 
+// LZCNT
+BUILTIN(__builtin_clzs, "UsUs", "")
+
+// BMI
+BUILTIN(__builtin_ctzs, "UsUs", "")
+
 #undef BUILTIN
diff --git a/lib/CodeGen/CGBuiltin.cpp b/lib/CodeGen/CGBuiltin.cpp
index 71d5156..2a467b5 100644
--- a/lib/CodeGen/CGBuiltin.cpp
+++ b/lib/CodeGen/CGBuiltin.cpp
@@ -2063,6 +2063,32 @@
 
   switch (BuiltinID) {
   default: return 0;
+  case X86::BI__builtin_clzs: {
+    Value *ArgValue = EmitScalarExpr(E->getArg(0));
+
+    llvm::Type *ArgType = ArgValue->getType();
+    Value *F = CGM.getIntrinsic(Intrinsic::ctlz, ArgType);
+
+    llvm::Type *ResultType = ConvertType(E->getType());
+    Value *Result = Builder.CreateCall2(F, ArgValue, Builder.getTrue());
+    if (Result->getType() != ResultType)
+      Result = Builder.CreateIntCast(Result, ResultType, /*isSigned*/true,
+                                     "cast");
+    return Result;
+  }
+  case X86::BI__builtin_ctzs: {
+    Value *ArgValue = EmitScalarExpr(E->getArg(0));
+
+    llvm::Type *ArgType = ArgValue->getType();
+    Value *F = CGM.getIntrinsic(Intrinsic::cttz, ArgType);
+
+    llvm::Type *ResultType = ConvertType(E->getType());
+    Value *Result = Builder.CreateCall2(F, ArgValue, Builder.getTrue());
+    if (Result->getType() != ResultType)
+      Result = Builder.CreateIntCast(Result, ResultType, /*isSigned*/true,
+                                     "cast");
+    return Result;
+  }
   case X86::BI__builtin_ia32_pslldi128:
   case X86::BI__builtin_ia32_psllqi128:
   case X86::BI__builtin_ia32_psllwi128:
diff --git a/lib/Headers/bmiintrin.h b/lib/Headers/bmiintrin.h
new file mode 100644
index 0000000..f2aae65
--- /dev/null
+++ b/lib/Headers/bmiintrin.h
@@ -0,0 +1,55 @@
+/*===---- bmiintrin.h - BMI 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.
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#if !defined __X86INTRIN_H && !defined __IMMINTRIN_H
+#error "Never use <bmiintrin.h> directly; include <x86intrin.h> instead."
+#endif
+
+#ifndef __BMI__
+# error "BMI instruction set not enabled"
+#endif /* __BMI__ */
+
+#ifndef __BMIINTRIN_H
+#define __BMIINTRIN_H
+
+static __inline__ unsigned short __attribute__((__always_inline__, __nodebug__))
+__tzcnt16(unsigned short __X)
+{
+  return __builtin_ctzs(__X);
+}
+
+static __inline__ unsigned int __attribute__((__always_inline__, __nodebug__))
+__tzcnt32(unsigned int __X)
+{
+  return __builtin_ctz(__X);
+}
+
+#ifdef __x86_64__
+static __inline__ unsigned long long __attribute__((__always_inline__, __nodebug__))
+__tzcnt64(unsigned long long __X)
+{
+  return __builtin_ctzll(__X);
+}
+#endif
+
+#endif /* __BMIINTRIN_H */
diff --git a/lib/Headers/immintrin.h b/lib/Headers/immintrin.h
index 53838ec..7499923 100644
--- a/lib/Headers/immintrin.h
+++ b/lib/Headers/immintrin.h
@@ -60,4 +60,12 @@
 #include <avx2intrin.h>
 #endif
 
+#ifdef __BMI__
+#include <bmiintrin.h>
+#endif
+
+#ifdef __LZCNT__
+#include <lzcntintrin.h>
+#endif
+
 #endif /* __IMMINTRIN_H */
diff --git a/lib/Headers/lzcntintrin.h b/lib/Headers/lzcntintrin.h
new file mode 100644
index 0000000..62ab5ca
--- /dev/null
+++ b/lib/Headers/lzcntintrin.h
@@ -0,0 +1,55 @@
+/*===---- lzcntintrin.h - LZCNT 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.
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#if !defined __X86INTRIN_H && !defined __IMMINTRIN_H
+#error "Never use <lzcntintrin.h> directly; include <x86intrin.h> instead."
+#endif
+
+#ifndef __LZCNT__
+# error "LZCNT instruction is not enabled"
+#endif /* __LZCNT__ */
+
+#ifndef __LZCNTINTRIN_H
+#define __LZCNTINTRIN_H
+
+static __inline__ unsigned short __attribute__((__always_inline__, __nodebug__))
+__lzcnt16(unsigned short __X)
+{
+  return __builtin_clzs(__X);
+}
+
+static __inline__ unsigned int __attribute__((__always_inline__, __nodebug__))
+__lzcnt32(unsigned int __X)
+{
+  return __builtin_clz(__X);
+}
+
+#ifdef __x86_64__
+static __inline__ unsigned long long __attribute__((__always_inline__, __nodebug__))
+__lzcnt64(unsigned long long __X)
+{
+  return __builtin_clzll(__X);
+}
+#endif
+
+#endif /* __LZCNTINTRIN_H */
diff --git a/lib/Headers/x86intrin.h b/lib/Headers/x86intrin.h
index e5e7a6a..c4baebe 100644
--- a/lib/Headers/x86intrin.h
+++ b/lib/Headers/x86intrin.h
@@ -26,6 +26,14 @@
 
 #include <immintrin.h>
 
+#ifdef __BMI__
+#include <bmiintrin.h>
+#endif
+
+#ifdef __LZCNT__
+#include <lzcntintrin.h>
+#endif
+
 // FIXME: SSE4A, 3dNOW, FMA4, XOP, LWP, ABM, POPCNT
 
 #endif /* __X86INTRIN_H */
diff --git a/test/CodeGen/bmi-builtins.c b/test/CodeGen/bmi-builtins.c
new file mode 100644
index 0000000..b44a125
--- /dev/null
+++ b/test/CodeGen/bmi-builtins.c
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 %s -O3 -triple=x86_64-apple-darwin -target-feature +bmi -S -o - | FileCheck %s
+
+// Don't include mm_malloc.h, it's system specific.
+#define __MM_MALLOC_H
+
+#include <x86intrin.h>
+
+unsigned short test__tzcnt16(unsigned short __X)
+{
+  // CHECK: tzcntw
+  return __tzcnt16(__X);
+}
+
+unsigned int test_tzcnt32(unsigned int __X)
+{
+  // CHECK: tzcntl
+  return __tzcnt32(__X);
+}
+
+unsigned long long test__tzcnt64(unsigned long long __X)
+{
+  // CHECK: tzcntq
+  return __tzcnt64(__X);
+}
diff --git a/test/CodeGen/lzcnt-builtins.c b/test/CodeGen/lzcnt-builtins.c
new file mode 100644
index 0000000..7b4da90
--- /dev/null
+++ b/test/CodeGen/lzcnt-builtins.c
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 %s -O3 -triple=x86_64-apple-darwin -target-feature +lzcnt -S -o - | FileCheck %s
+
+// Don't include mm_malloc.h, it's system specific.
+#define __MM_MALLOC_H
+
+#include <x86intrin.h>
+
+unsigned short test__lzcnt16(unsigned short __X)
+{
+  // CHECK: lzcntw
+  return __lzcnt16(__X);
+}
+
+unsigned int test_lzcnt32(unsigned int __X)
+{
+  // CHECK: lzcntl
+  return __lzcnt32(__X);
+}
+
+unsigned long long test__lzcnt64(unsigned long long __X)
+{
+  // CHECK: lzcntq
+  return __lzcnt64(__X);
+}