Index: cfe/trunk/include/clang/Basic/Builtins.h
===================================================================
--- cfe/trunk/include/clang/Basic/Builtins.h
+++ cfe/trunk/include/clang/Basic/Builtins.h
@@ -38,6 +38,7 @@
   MS_LANG = 0x10,     // builtin requires MS mode.
   OCLC20_LANG = 0x20, // builtin for OpenCL C 2.0 only.
   OCLC1X_LANG = 0x40, // builtin for OpenCL C 1.x only.
+  OMP_LANG = 0x80,    // builtin requires OpenMP.
   ALL_LANGUAGES = C_LANG | CXX_LANG | OBJC_LANG, // builtin for all languages.
   ALL_GNU_LANGUAGES = ALL_LANGUAGES | GNU_LANG,  // builtin requires GNU mode.
   ALL_MS_LANGUAGES = ALL_LANGUAGES | MS_LANG,    // builtin requires MS mode.
Index: cfe/trunk/include/clang/Basic/Builtins.def
===================================================================
--- cfe/trunk/include/clang/Basic/Builtins.def
+++ cfe/trunk/include/clang/Basic/Builtins.def
@@ -1434,6 +1434,9 @@
 BUILTIN(__builtin_os_log_format_buffer_size, "zcC*.", "p:0:nut")
 BUILTIN(__builtin_os_log_format, "v*v*cC*.", "p:0:nt")
 
+// OpenMP 4.0
+LANGBUILTIN(omp_is_initial_device, "i", "nc", OMP_LANG)
+
 // Builtins for XRay
 BUILTIN(__xray_customevent, "vcC*z", "")
 
Index: cfe/trunk/lib/AST/ExprConstant.cpp
===================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp
+++ cfe/trunk/lib/AST/ExprConstant.cpp
@@ -7929,6 +7929,9 @@
     return BuiltinOp == Builtin::BI__atomic_always_lock_free ?
         Success(0, E) : Error(E);
   }
+  case Builtin::BIomp_is_initial_device:
+    // We can decide statically which value the runtime would return if called.
+    return Success(Info.getLangOpts().OpenMPIsDevice ? 0 : 1, E);
   }
 }
 
Index: cfe/trunk/lib/Basic/Builtins.cpp
===================================================================
--- cfe/trunk/lib/Basic/Builtins.cpp
+++ cfe/trunk/lib/Basic/Builtins.cpp
@@ -75,8 +75,9 @@
                           (BuiltinInfo.Langs & ALL_OCLC_LANGUAGES) == OCLC20_LANG;
   bool OclCUnsupported = !LangOpts.OpenCL &&
                          (BuiltinInfo.Langs & ALL_OCLC_LANGUAGES);
+  bool OpenMPUnsupported = !LangOpts.OpenMP && BuiltinInfo.Langs == OMP_LANG;
   return !BuiltinsUnsupported && !MathBuiltinsUnsupported && !OclCUnsupported &&
-         !OclC1Unsupported && !OclC2Unsupported &&
+         !OclC1Unsupported && !OclC2Unsupported && !OpenMPUnsupported &&
          !GnuModeUnsupported && !MSModeUnsupported && !ObjCUnsupported;
 }
 
Index: cfe/trunk/test/OpenMP/is_initial_device.c
===================================================================
--- cfe/trunk/test/OpenMP/is_initial_device.c
+++ cfe/trunk/test/OpenMP/is_initial_device.c
@@ -0,0 +1,36 @@
+// REQUIRES: powerpc-registered-target
+
+// RUN: %clang_cc1 -verify -fopenmp -x c -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-unknown-unknown \
+// RUN:            -emit-llvm-bc %s -o %t-ppc-host.bc
+// RUN: %clang_cc1 -verify -fopenmp -x ir -triple powerpc64le-unknown-unknown -emit-llvm \
+// RUN:             %t-ppc-host.bc -o - | FileCheck %s -check-prefixes HOST,OUTLINED
+// RUN: %clang_cc1 -verify -fopenmp -x c -triple powerpc64le-unknown-unknown -emit-llvm -fopenmp-is-device \
+// RUN:             %s -fopenmp-host-ir-file-path %t-ppc-host.bc -o - | FileCheck %s -check-prefixes DEVICE,OUTLINED
+
+// expected-no-diagnostics
+int check() {
+  int host = omp_is_initial_device();
+  int device;
+#pragma omp target map(tofrom: device)
+  {
+    device = omp_is_initial_device();
+  }
+
+  return host + device;
+}
+
+// The host should get a value of 1:
+// HOST: define{{.*}} @check()
+// HOST: [[HOST:%.*]] = alloca i32
+// HOST: store i32 1, i32* [[HOST]]
+
+// OUTLINED: define{{.*}} @{{.*}}omp_offloading{{.*}}(i32*{{.*}} [[DEVICE_ARGUMENT:%.*]])
+// OUTLINED: [[DEVICE_ADDR_STORAGE:%.*]] = alloca i32*
+// OUTLINED: store i32* [[DEVICE_ARGUMENT]], i32** [[DEVICE_ADDR_STORAGE]]
+// OUTLINED: [[DEVICE_ADDR:%.*]] = load i32*, i32** [[DEVICE_ADDR_STORAGE]]
+
+// The outlined function that is called as fallback also runs on the host:
+// HOST: store i32 1, i32* [[DEVICE_ADDR]]
+
+// The device should get a value of 0:
+// DEVICE: store i32 0, i32* [[DEVICE_ADDR]]