Index: cfe/trunk/include/clang/Driver/Options.td
===================================================================
--- cfe/trunk/include/clang/Driver/Options.td
+++ cfe/trunk/include/clang/Driver/Options.td
@@ -815,7 +815,7 @@
   HelpText<"Emit all declarations, even if unused">;
 def femulated_tls : Flag<["-"], "femulated-tls">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Use emutls functions to access thread_local variables">;
-def fno_emulated_tls : Flag<["-"], "fno-emulated-tls">, Group<f_Group>;
+def fno_emulated_tls : Flag<["-"], "fno-emulated-tls">, Group<f_Group>, Flags<[CC1Option]>;
 def fencoding_EQ : Joined<["-"], "fencoding=">, Group<f_Group>;
 def ferror_limit_EQ : Joined<["-"], "ferror-limit=">, Group<f_Group>, Flags<[CoreOption]>;
 def fexceptions : Flag<["-"], "fexceptions">, Group<f_Group>, Flags<[CC1Option]>,
Index: cfe/trunk/include/clang/Frontend/CodeGenOptions.def
===================================================================
--- cfe/trunk/include/clang/Frontend/CodeGenOptions.def
+++ cfe/trunk/include/clang/Frontend/CodeGenOptions.def
@@ -69,7 +69,8 @@
 CODEGENOPT(EmitGcovArcs      , 1, 0) ///< Emit coverage data files, aka. GCDA.
 CODEGENOPT(EmitGcovNotes     , 1, 0) ///< Emit coverage "notes" files, aka GCNO.
 CODEGENOPT(EmitOpenCLArgMetadata , 1, 0) ///< Emit OpenCL kernel arg metadata.
-CODEGENOPT(EmulatedTLS       , 1, 0) ///< Set when -femulated-tls is enabled.
+CODEGENOPT(EmulatedTLS       , 1, 0) ///< Set by default or -f[no-]emulated-tls.
+CODEGENOPT(ExplicitEmulatedTLS , 1, 0) ///< Set if -f[no-]emulated-tls is used.
 /// \brief Embed Bitcode mode (off/all/bitcode/marker).
 ENUM_CODEGENOPT(EmbedBitcode, EmbedBitcodeKind, 2, Embed_Off)
 CODEGENOPT(ForbidGuardVariables , 1, 0) ///< Issue errors if C++ guard variables
Index: cfe/trunk/lib/CodeGen/BackendUtil.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/BackendUtil.cpp
+++ cfe/trunk/lib/CodeGen/BackendUtil.cpp
@@ -433,6 +433,7 @@
   Options.DataSections = CodeGenOpts.DataSections;
   Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
+  Options.ExplicitEmulatedTLS = CodeGenOpts.ExplicitEmulatedTLS;
   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
   Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
 
Index: cfe/trunk/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- cfe/trunk/lib/Driver/ToolChains/Clang.cpp
+++ cfe/trunk/lib/Driver/ToolChains/Clang.cpp
@@ -3937,13 +3937,9 @@
   Args.AddLastArg(CmdArgs, options::OPT_femit_all_decls);
   Args.AddLastArg(CmdArgs, options::OPT_fheinous_gnu_extensions);
   Args.AddLastArg(CmdArgs, options::OPT_fno_operator_names);
-  // Emulated TLS is enabled by default on Android and OpenBSD, and can be enabled
-  // manually with -femulated-tls.
-  bool EmulatedTLSDefault = Triple.isAndroid() || Triple.isOSOpenBSD() ||
-                            Triple.isWindowsCygwinEnvironment();
-  if (Args.hasFlag(options::OPT_femulated_tls, options::OPT_fno_emulated_tls,
-                   EmulatedTLSDefault))
-    CmdArgs.push_back("-femulated-tls");
+  Args.AddLastArg(CmdArgs, options::OPT_femulated_tls,
+                  options::OPT_fno_emulated_tls);
+
   // AltiVec-like language extensions aren't relevant for assembling.
   if (!isa<PreprocessJobAction>(JA) || Output.getType() != types::TY_PP_Asm)
     Args.AddLastArg(CmdArgs, options::OPT_fzvector);
Index: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp
@@ -942,8 +942,12 @@
     }
   }
 
-  Opts.EmulatedTLS =
-      Args.hasFlag(OPT_femulated_tls, OPT_fno_emulated_tls, false);
+  if (Args.getLastArg(OPT_femulated_tls) ||
+      Args.getLastArg(OPT_fno_emulated_tls)) {
+    Opts.ExplicitEmulatedTLS = true;
+    Opts.EmulatedTLS =
+        Args.hasFlag(OPT_femulated_tls, OPT_fno_emulated_tls, false);
+  }
 
   if (Arg *A = Args.getLastArg(OPT_ftlsmodel_EQ)) {
     StringRef Name = A->getValue();
Index: cfe/trunk/test/Driver/emulated-tls.cpp
===================================================================
--- cfe/trunk/test/Driver/emulated-tls.cpp
+++ cfe/trunk/test/Driver/emulated-tls.cpp
@@ -1,7 +1,42 @@
-// Cygwin and OpenBSD use emutls. Clang should pass -femulated-tls to cc1
-// and cc1 should pass EmulatedTLS to LLVM CodeGen.
-// FIXME: Add more targets here to use emutls.
-// RUN: %clang -### -std=c++11 -target i686-pc-cygwin %s 2>&1 | FileCheck %s
-// RUN: %clang -### -std=c++11 -target i686-pc-openbsd %s 2>&1 | FileCheck %s
+// Android, Cygwin and OpenBSD use emutls by default.
+// Clang should pass -femulated-tls or -fno-emulated-tls to cc1 if they are used,
+// and cc1 should set up EmulatedTLS and ExplicitEmulatedTLS to LLVM CodeGen.
+//
+// RUN: %clang -### -target arm-linux-androideabi %s 2>&1 \
+// RUN: | FileCheck -check-prefix=DEFAULT %s
+// RUN: %clang -### -target arm-linux-gnu %s 2>&1 \
+// RUN: | FileCheck -check-prefix=DEFAULT %s
+// RUN: %clang -### -target i686-pc-cygwin %s 2>&1 \
+// RUN: | FileCheck -check-prefix=DEFAULT %s
+// RUN: %clang -### -target i686-pc-openbsd %s 2>&1 \
+// RUN: | FileCheck -check-prefix=DEFAULT %s
 
-// CHECK: "-cc1" {{.*}}"-femulated-tls"
+// RUN: %clang -### -target arm-linux-androideabi -fno-emulated-tls -femulated-tls %s 2>&1 \
+// RUN: | FileCheck -check-prefix=EMU %s
+// RUN: %clang -### -target arm-linux-gnu %s -fno-emulated-tls -femulated-tls 2>&1 \
+// RUN: | FileCheck -check-prefix=EMU %s
+// RUN: %clang -### -target i686-pc-cygwin %s -fno-emulated-tls -femulated-tls 2>&1 \
+// RUN: | FileCheck -check-prefix=EMU %s
+// RUN: %clang -### -target i686-pc-openbsd %s -fno-emulated-tls -femulated-tls 2>&1 \
+// RUN: | FileCheck -check-prefix=EMU %s
+
+// RUN: %clang -### -target arm-linux-androideabi -femulated-tls -fno-emulated-tls %s 2>&1 \
+// RUN: | FileCheck -check-prefix=NOEMU %s
+// RUN: %clang -### -target arm-linux-gnu %s -femulated-tls -fno-emulated-tls 2>&1 \
+// RUN: | FileCheck -check-prefix=NOEMU %s
+// RUN: %clang -### -target i686-pc-cygwin %s -femulated-tls -fno-emulated-tls 2>&1 \
+// RUN: | FileCheck -check-prefix=NOEMU %s
+// RUN: %clang -### -target i686-pc-openbsd %s -femulated-tls -fno-emulated-tls 2>&1 \
+// RUN: | FileCheck -check-prefix=NOEMU %s
+
+
+// Default without -f[no-]emulated-tls, will be decided by the target triple.
+// DEFAULT-NOT: "-cc1" {{.*}}"-femulated-tls"
+// DEFAULT-NOT: "-cc1" {{.*}}"-fno-emulated-tls"
+
+// Explicit and last -f[no-]emulated-tls flag will be passed to cc1.
+// EMU: "-cc1" {{.*}}"-femulated-tls"
+// EMU-NOT: "-cc1" {{.*}}"-fno-emulated-tls"
+
+// NOEMU: "-cc1" {{.*}}"-fno-emulated-tls"
+// NOEMU-NOT: "-cc1" {{.*}}"-femulated-tls"