Index: cfe/trunk/include/clang/Driver/Driver.h
===================================================================
--- cfe/trunk/include/clang/Driver/Driver.h
+++ cfe/trunk/include/clang/Driver/Driver.h
@@ -405,12 +405,12 @@
   bool IsUsingLTO(const llvm::opt::ArgList &Args) const;
 
 private:
-  /// \brief Retrieves a ToolChain for a particular target triple.
+  /// \brief Retrieves a ToolChain for a particular \p Target triple.
   ///
   /// Will cache ToolChains for the life of the driver object, and create them
   /// on-demand.
   const ToolChain &getToolChain(const llvm::opt::ArgList &Args,
-                                StringRef DarwinArchName = "") const;
+                                const llvm::Triple &Target) const;
 
   /// @}
 
Index: cfe/trunk/lib/Driver/Driver.cpp
===================================================================
--- cfe/trunk/lib/Driver/Driver.cpp
+++ cfe/trunk/lib/Driver/Driver.cpp
@@ -281,6 +281,83 @@
   return DAL;
 }
 
+/// \brief Compute target triple from args.
+///
+/// This routine provides the logic to compute a target triple from various
+/// args passed to the driver and the default triple string.
+static llvm::Triple computeTargetTriple(StringRef DefaultTargetTriple,
+                                        const ArgList &Args,
+                                        StringRef DarwinArchName = "") {
+  // FIXME: Already done in Compilation *Driver::BuildCompilation
+  if (const Arg *A = Args.getLastArg(options::OPT_target))
+    DefaultTargetTriple = A->getValue();
+
+  llvm::Triple Target(llvm::Triple::normalize(DefaultTargetTriple));
+
+  // Handle Apple-specific options available here.
+  if (Target.isOSBinFormatMachO()) {
+    // If an explict Darwin arch name is given, that trumps all.
+    if (!DarwinArchName.empty()) {
+      tools::darwin::setTripleTypeForMachOArchName(Target, DarwinArchName);
+      return Target;
+    }
+
+    // Handle the Darwin '-arch' flag.
+    if (Arg *A = Args.getLastArg(options::OPT_arch)) {
+      StringRef ArchName = A->getValue();
+      tools::darwin::setTripleTypeForMachOArchName(Target, ArchName);
+    }
+  }
+
+  // Handle pseudo-target flags '-mlittle-endian'/'-EL' and
+  // '-mbig-endian'/'-EB'.
+  if (Arg *A = Args.getLastArg(options::OPT_mlittle_endian,
+                               options::OPT_mbig_endian)) {
+    if (A->getOption().matches(options::OPT_mlittle_endian)) {
+      llvm::Triple LE = Target.getLittleEndianArchVariant();
+      if (LE.getArch() != llvm::Triple::UnknownArch)
+        Target = std::move(LE);
+    } else {
+      llvm::Triple BE = Target.getBigEndianArchVariant();
+      if (BE.getArch() != llvm::Triple::UnknownArch)
+        Target = std::move(BE);
+    }
+  }
+
+  // Skip further flag support on OSes which don't support '-m32' or '-m64'.
+  if (Target.getArchName() == "tce" || Target.getOS() == llvm::Triple::Minix)
+    return Target;
+
+  // Handle pseudo-target flags '-m64', '-mx32', '-m32' and '-m16'.
+  if (Arg *A = Args.getLastArg(options::OPT_m64, options::OPT_mx32,
+                               options::OPT_m32, options::OPT_m16)) {
+    llvm::Triple::ArchType AT = llvm::Triple::UnknownArch;
+
+    if (A->getOption().matches(options::OPT_m64)) {
+      AT = Target.get64BitArchVariant().getArch();
+      if (Target.getEnvironment() == llvm::Triple::GNUX32)
+        Target.setEnvironment(llvm::Triple::GNU);
+    } else if (A->getOption().matches(options::OPT_mx32) &&
+               Target.get64BitArchVariant().getArch() == llvm::Triple::x86_64) {
+      AT = llvm::Triple::x86_64;
+      Target.setEnvironment(llvm::Triple::GNUX32);
+    } else if (A->getOption().matches(options::OPT_m32)) {
+      AT = Target.get32BitArchVariant().getArch();
+      if (Target.getEnvironment() == llvm::Triple::GNUX32)
+        Target.setEnvironment(llvm::Triple::GNU);
+    } else if (A->getOption().matches(options::OPT_m16) &&
+               Target.get32BitArchVariant().getArch() == llvm::Triple::x86) {
+      AT = llvm::Triple::x86;
+      Target.setEnvironment(llvm::Triple::CODE16);
+    }
+
+    if (AT != llvm::Triple::UnknownArch && AT != Target.getArch())
+      Target.setArch(AT);
+  }
+
+  return Target;
+}
+
 Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   llvm::PrettyStackTraceString CrashInfo("Compilation construction");
 
@@ -367,7 +444,8 @@
   DerivedArgList *TranslatedArgs = TranslateInputArgs(*UArgs);
 
   // Owned by the host.
-  const ToolChain &TC = getToolChain(*UArgs);
+  const ToolChain &TC =
+      getToolChain(*UArgs, computeTargetTriple(DefaultTargetTriple, *UArgs));
 
   // The compilation takes ownership of Args.
   Compilation *C = new Compilation(*this, TC, UArgs.release(), TranslatedArgs);
@@ -1551,7 +1629,9 @@
     const char *ArchName = BAA->getArchName();
 
     if (ArchName)
-      TC = &getToolChain(C.getArgs(), ArchName);
+      TC = &getToolChain(
+          C.getArgs(),
+          computeTargetTriple(DefaultTargetTriple, C.getArgs(), ArchName));
     else
       TC = &C.getDefaultToolChain();
 
@@ -1906,87 +1986,8 @@
   return Path.str();
 }
 
-/// \brief Compute target triple from args.
-///
-/// This routine provides the logic to compute a target triple from various
-/// args passed to the driver and the default triple string.
-static llvm::Triple computeTargetTriple(StringRef DefaultTargetTriple,
-                                        const ArgList &Args,
-                                        StringRef DarwinArchName) {
-  // FIXME: Already done in Compilation *Driver::BuildCompilation
-  if (const Arg *A = Args.getLastArg(options::OPT_target))
-    DefaultTargetTriple = A->getValue();
-
-  llvm::Triple Target(llvm::Triple::normalize(DefaultTargetTriple));
-
-  // Handle Apple-specific options available here.
-  if (Target.isOSBinFormatMachO()) {
-    // If an explict Darwin arch name is given, that trumps all.
-    if (!DarwinArchName.empty()) {
-      tools::darwin::setTripleTypeForMachOArchName(Target, DarwinArchName);
-      return Target;
-    }
-
-    // Handle the Darwin '-arch' flag.
-    if (Arg *A = Args.getLastArg(options::OPT_arch)) {
-      StringRef ArchName = A->getValue();
-      tools::darwin::setTripleTypeForMachOArchName(Target, ArchName);
-    }
-  }
-
-  // Handle pseudo-target flags '-mlittle-endian'/'-EL' and
-  // '-mbig-endian'/'-EB'.
-  if (Arg *A = Args.getLastArg(options::OPT_mlittle_endian,
-                               options::OPT_mbig_endian)) {
-    if (A->getOption().matches(options::OPT_mlittle_endian)) {
-      llvm::Triple LE = Target.getLittleEndianArchVariant();
-      if (LE.getArch() != llvm::Triple::UnknownArch)
-        Target = std::move(LE);
-    } else {
-      llvm::Triple BE = Target.getBigEndianArchVariant();
-      if (BE.getArch() != llvm::Triple::UnknownArch)
-        Target = std::move(BE);
-    }
-  }
-
-  // Skip further flag support on OSes which don't support '-m32' or '-m64'.
-  if (Target.getArchName() == "tce" || Target.getOS() == llvm::Triple::Minix)
-    return Target;
-
-  // Handle pseudo-target flags '-m64', '-mx32', '-m32' and '-m16'.
-  if (Arg *A = Args.getLastArg(options::OPT_m64, options::OPT_mx32,
-                               options::OPT_m32, options::OPT_m16)) {
-    llvm::Triple::ArchType AT = llvm::Triple::UnknownArch;
-
-    if (A->getOption().matches(options::OPT_m64)) {
-      AT = Target.get64BitArchVariant().getArch();
-      if (Target.getEnvironment() == llvm::Triple::GNUX32)
-        Target.setEnvironment(llvm::Triple::GNU);
-    } else if (A->getOption().matches(options::OPT_mx32) &&
-               Target.get64BitArchVariant().getArch() == llvm::Triple::x86_64) {
-      AT = llvm::Triple::x86_64;
-      Target.setEnvironment(llvm::Triple::GNUX32);
-    } else if (A->getOption().matches(options::OPT_m32)) {
-      AT = Target.get32BitArchVariant().getArch();
-      if (Target.getEnvironment() == llvm::Triple::GNUX32)
-        Target.setEnvironment(llvm::Triple::GNU);
-    } else if (A->getOption().matches(options::OPT_m16) &&
-               Target.get32BitArchVariant().getArch() == llvm::Triple::x86) {
-      AT = llvm::Triple::x86;
-      Target.setEnvironment(llvm::Triple::CODE16);
-    }
-
-    if (AT != llvm::Triple::UnknownArch && AT != Target.getArch())
-      Target.setArch(AT);
-  }
-
-  return Target;
-}
-
 const ToolChain &Driver::getToolChain(const ArgList &Args,
-                                      StringRef DarwinArchName) const {
-  llvm::Triple Target =
-      computeTargetTriple(DefaultTargetTriple, Args, DarwinArchName);
+                                      const llvm::Triple &Target) const {
 
   ToolChain *&TC = ToolChains[Target.str()];
   if (!TC) {