Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -738,7 +738,8 @@
 
 def fobjc_sender_dependent_dispatch : Flag<["-"], "fobjc-sender-dependent-dispatch">, Group<f_Group>;
 def fomit_frame_pointer : Flag<["-"], "fomit-frame-pointer">, Group<f_Group>;
-def fopenmp : Flag<["-"], "fopenmp">, Group<f_Group>, Flags<[CC1Option]>;
+def fopenmp : Flag<["-"], "fopenmp">, Group<f_Group>, Flags<[CC1Option, NoArgumentUnused]>;
+def fopenmp_EQ : Joined<["-"], "fopenmp=">, Group<f_Group>, Flags<[CC1Option]>;
 def fno_optimize_sibling_calls : Flag<["-"], "fno-optimize-sibling-calls">, Group<f_Group>;
 def foptimize_sibling_calls : Flag<["-"], "foptimize-sibling-calls">, Group<f_Group>;
 def force__cpusubtype__ALL : Flag<["-"], "force_cpusubtype_ALL">;
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -5234,9 +5234,16 @@
 
   Args.AddAllArgs(CmdArgs, options::OPT_L);
 
-  if (Args.hasArg(options::OPT_fopenmp))
+  if (Args.hasArg(options::OPT_fopenmp)) {
     // This is more complicated in gcc...
     CmdArgs.push_back("-lgomp");
+  } else if (const Arg *A = Args.getLastArg(options::OPT_fopenmp_EQ)) {
+    if (StringRef(A->getValue()) == "libiomp5")
+      CmdArgs.push_back("-liomp5");
+    else
+      getToolChain().getDriver().Diag(diag::err_drv_unsupported_option_argument)
+        << A->getOption().getName() << A->getValue();
+  }
 
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs);
   
@@ -6831,6 +6838,12 @@
         // FIXME: Exclude this for platforms with libgomp that don't require
         // librt. Most modern Linux platforms require it, but some may not.
         CmdArgs.push_back("-lrt");
+      } else if (const Arg *A = Args.getLastArg(options::OPT_fopenmp_EQ)) {
+        if (StringRef(A->getValue()) == "libiomp5")
+          CmdArgs.push_back("-liomp5");
+        else
+          D.Diag(diag::err_drv_unsupported_option_argument)
+            << A->getOption().getName() << A->getValue();
       }
 
       AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -1430,8 +1430,8 @@
     Opts.setMSPointerToMemberRepresentationMethod(InheritanceModel);
   }
 
-  // Check if -fopenmp is specified.
-  Opts.OpenMP = Args.hasArg(OPT_fopenmp);
+  // Check if -fopenmp= is specified.
+  Opts.OpenMP =  Args.hasArg(options::OPT_fopenmp_EQ);
 
   // Record whether the __DEPRECATED define was requested.
   Opts.Deprecated = Args.hasFlag(OPT_fdeprecated_macro,
Index: test/OpenMP/linking.c
===================================================================
--- test/OpenMP/linking.c
+++ test/OpenMP/linking.c
@@ -1,5 +1,5 @@
 // Test the that the driver produces reasonable linker invocations with
-// -fopenmp.
+// -fopenmp or -fopenmp=libiomp5.
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -fopenmp -target i386-unknown-linux \
@@ -14,3 +14,42 @@
 // CHECK-LD-64: "{{.*}}ld{{(.exe)?}}"
 // CHECK-LD-64: "-lgomp" "-lrt" "-lgcc"
 // CHECK-LD-64: "-lpthread" "-lc"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -fopenmp=libiomp5 -target i386-unknown-linux \
+// RUN:   | FileCheck --check-prefix=CHECK-IOMP5-LD-32 %s
+// CHECK-IOMP5-LD-32: "{{.*}}ld{{(.exe)?}}"
+// CHECK-IOMP5-LD-32: "-liomp5"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -fopenmp=libiomp5 -target x86_64-unknown-linux \
+// RUN:   | FileCheck --check-prefix=CHECK-IOMP5-LD-64 %s
+// CHECK-IOMP5-LD-64: "{{.*}}ld{{(.exe)?}}"
+// CHECK-IOMP5-LD-64: "-liomp5"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -fopenmp=lib -target i386-unknown-linux \
+// RUN:   | FileCheck --check-prefix=CHECK-LIB-LD-32 %s
+// CHECK-LIB-LD-32: error: unsupported argument 'lib' to option 'fopenmp='
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -fopenmp=lib -target x86_64-unknown-linux \
+// RUN:   | FileCheck --check-prefix=CHECK-LIB-LD-64 %s
+// CHECK-LIB-LD-64: error: unsupported argument 'lib' to option 'fopenmp='
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -fopenmp -fopenmp=libiomp5 -target i386-unknown-linux \
+// RUN:   | FileCheck --check-prefix=CHECK-LD-WARN-32 %s
+// CHECK-LD-WARN-32: warning: argument unused during compilation: '-fopenmp=libiomp5'
+// CHECK-LD-WARN-32: "{{.*}}ld{{(.exe)?}}"
+// CHECK-LD-WARN-32: "-lgomp" "-lrt" "-lgcc"
+// CHECK-LD-WARN-32: "-lpthread" "-lc"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -fopenmp -fopenmp=libiomp5 -target x86_64-unknown-linux \
+// RUN:   | FileCheck --check-prefix=CHECK-LD-WARN-64 %s
+// CHECK-LD-WARN-64: warning: argument unused during compilation: '-fopenmp=libiomp5'
+// CHECK-LD-WARN-64: "{{.*}}ld{{(.exe)?}}"
+// CHECK-LD-WARN-64: "-lgomp" "-lrt" "-lgcc"
+// CHECK-LD-WARN-64: "-lpthread" "-lc"
+//
Index: test/OpenMP/openmp_common.c
===================================================================
--- test/OpenMP/openmp_common.c
+++ test/OpenMP/openmp_common.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 -o - %s
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ferror-limit 100 -o - %s
 
 #pragma omp // expected-error {{expected an OpenMP directive}}
 #pragma omp unknown_directive // expected-error {{expected an OpenMP directive}}
Index: test/OpenMP/parallel_ast_print.cpp
===================================================================
--- test/OpenMP/parallel_ast_print.cpp
+++ test/OpenMP/parallel_ast_print.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -verify -fopenmp -ast-print %s | FileCheck %s
-// RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
-// RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp=libiomp5 -x c++ -std=c++11 -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp=libiomp5 -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
 // expected-no-diagnostics
 
 #ifndef HEADER
Index: test/OpenMP/parallel_default_messages.cpp
===================================================================
--- test/OpenMP/parallel_default_messages.cpp
+++ test/OpenMP/parallel_default_messages.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 -o - %s
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ferror-limit 100 -o - %s
 
 void foo();
 
Index: test/OpenMP/parallel_firstprivate_messages.cpp
===================================================================
--- test/OpenMP/parallel_firstprivate_messages.cpp
+++ test/OpenMP/parallel_firstprivate_messages.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 %s
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ferror-limit 100 %s
 
 void foo() {
 }
Index: test/OpenMP/parallel_if_messages.cpp
===================================================================
--- test/OpenMP/parallel_if_messages.cpp
+++ test/OpenMP/parallel_if_messages.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 %s
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ferror-limit 100 %s
 
 void foo() {
 }
Index: test/OpenMP/parallel_messages.cpp
===================================================================
--- test/OpenMP/parallel_messages.cpp
+++ test/OpenMP/parallel_messages.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 -std=c++11 -o - %s
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ferror-limit 100 -std=c++11 -o - %s
 
 void foo() {
 }
Index: test/OpenMP/parallel_private_messages.cpp
===================================================================
--- test/OpenMP/parallel_private_messages.cpp
+++ test/OpenMP/parallel_private_messages.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 %s
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ferror-limit 100 %s
 
 void foo() {
 }
Index: test/OpenMP/parallel_shared_messages.cpp
===================================================================
--- test/OpenMP/parallel_shared_messages.cpp
+++ test/OpenMP/parallel_shared_messages.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 %s
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ferror-limit 100 %s
 
 void foo() {
 }
Index: test/OpenMP/predefined_macro.c
===================================================================
--- test/OpenMP/predefined_macro.c
+++ test/OpenMP/predefined_macro.c
@@ -1,32 +1,32 @@
-// RUN: %clang_cc1 -fopenmp -verify -DFOPENMP -o - %s
+// RUN: %clang_cc1 -fopenmp=libiomp5 -verify -DFOPENMP -o - %s
 // RUN: %clang_cc1 -verify -o - %s
 // expected-no-diagnostics
 #ifdef FOPENMP
-// -fopenmp option is specified
+// -fopenmp=libiomp5 option is specified
 #ifndef _OPENMP
 #error "No _OPENMP macro is defined with -fopenmp option"
 #elsif _OPENMP != 201107
 #error "_OPENMP has incorrect value"
 #endif //_OPENMP
 #else
-// No -fopenmp option is specified
+// No -fopenmp=libiomp5 option is specified
 #ifdef _OPENMP
 #error "_OPENMP macro is defined without -fopenmp option"
 #endif // _OPENMP
 #endif // FOPENMP
 
-// RUN: %clang_cc1 -fopenmp -verify -DFOPENMP -o - %s
+// RUN: %clang_cc1 -fopenmp=libiomp5 -verify -DFOPENMP -o - %s
 // RUN: %clang_cc1 -verify -o - %s
 // expected-no-diagnostics
 #ifdef FOPENMP
-// -fopenmp option is specified
+// -fopenmp=libiomp5 option is specified
 #ifndef _OPENMP
 #error "No _OPENMP macro is defined with -fopenmp option"
 #elsif _OPENMP != 201107
 #error "_OPENMP has incorrect value"
 #endif // _OPENMP
 #else
-// No -fopenmp option is specified
+// No -fopenmp=libiomp5 option is specified
 #ifdef _OPENMP
 #error "_OPENMP macro is defined without -fopenmp option"
 #endif // _OPENMP
Index: test/OpenMP/simd_ast_print.cpp
===================================================================
--- test/OpenMP/simd_ast_print.cpp
+++ test/OpenMP/simd_ast_print.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -verify -fopenmp -ast-print %s | FileCheck %s
-// RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
-// RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp=libiomp5 -x c++ -std=c++11 -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp=libiomp5 -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
 // expected-no-diagnostics
 
 #ifndef HEADER
Index: test/OpenMP/simd_misc_messages.c
===================================================================
--- test/OpenMP/simd_misc_messages.c
+++ test/OpenMP/simd_misc_messages.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -fopenmp -verify %s
+// RUN: %clang_cc1 -fsyntax-only -fopenmp=libiomp5 -verify %s
 
 // expected-error@+1 {{unexpected OpenMP directive '#pragma omp simd'}}
 #pragma omp simd
Index: test/OpenMP/threadprivate_ast_print.cpp
===================================================================
--- test/OpenMP/threadprivate_ast_print.cpp
+++ test/OpenMP/threadprivate_ast_print.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -verify -fopenmp -ast-print %s | FileCheck %s
-// RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
-// RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print
+// RUN: %clang_cc1 -verify -fopenmp=libiomp5 -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp=libiomp5 -x c++ -std=c++11 -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp=libiomp5 -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print
 // expected-no-diagnostics
 
 #ifndef HEADER
Index: test/OpenMP/threadprivate_messages.cpp
===================================================================
--- test/OpenMP/threadprivate_messages.cpp
+++ test/OpenMP/threadprivate_messages.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify -fopenmp -ferror-limit 100 %s
+// RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -verify -fopenmp=libiomp5 -ferror-limit 100 %s
 
 #pragma omp threadprivate // expected-error {{expected '(' after 'threadprivate'}}
 #pragma omp threadprivate( // expected-error {{expected identifier}} expected-error {{expected ')'}} expected-note {{to match this '('}}