diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 1856364..9ef3469 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1126,10 +1126,59 @@
   }
 }
 
+static const char *getX86TargetCPU(const ArgList &Args,
+                                   const llvm::Triple &Triple) {
+  if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
+    if (StringRef(A->getValue()) != "native")
+      return A->getValue();
+
+    // FIXME: Reject attempts to use -march=native unless the target matches
+    // the host.
+    //
+    // FIXME: We should also incorporate the detected target features for use
+    // with -native.
+    std::string CPU = llvm::sys::getHostCPUName();
+    if (!CPU.empty() && CPU != "generic")
+      return Args.MakeArgString(CPU);
+  }
+
+  // Select the default CPU if none was given (or detection failed).
+
+  if (Triple.getArch() != llvm::Triple::x86_64 &&
+      Triple.getArch() != llvm::Triple::x86)
+    return 0; // This routine is only handling x86 targets.
+
+  bool Is64Bit = Triple.getArch() == llvm::Triple::x86_64;
+
+  // FIXME: Need target hooks.
+  if (Triple.isOSDarwin())
+    return Is64Bit ? "core2" : "yonah";
+
+  // Everything else goes to x86-64 in 64-bit mode.
+  if (Is64Bit)
+    return "x86-64";
+
+  if (Triple.getOSName().startswith("haiku"))
+    return "i586";
+  if (Triple.getOSName().startswith("openbsd"))
+    return "i486";
+  if (Triple.getOSName().startswith("bitrig"))
+    return "i686";
+  if (Triple.getOSName().startswith("freebsd"))
+    return "i486";
+  if (Triple.getOSName().startswith("netbsd"))
+    return "i486";
+  // All x86 devices running Android have core2 as their common
+  // denominator. This makes a better choice than pentium4.
+  if (Triple.getEnvironment() == llvm::Triple::Android)
+    return "core2";
+
+  // Fallback to p4.
+  return "pentium4";
+}
+
 void Clang::AddX86TargetArgs(const ArgList &Args,
                              ArgStringList &CmdArgs) const {
-  const bool isAndroid =
-    getToolChain().getTriple().getEnvironment() == llvm::Triple::Android;
   if (!Args.hasFlag(options::OPT_mred_zone,
                     options::OPT_mno_red_zone,
                     true) ||
@@ -1142,65 +1191,7 @@
                    false))
     CmdArgs.push_back("-no-implicit-float");
 
-  const char *CPUName = 0;
-  if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
-    if (StringRef(A->getValue()) == "native") {
-      // FIXME: Reject attempts to use -march=native unless the target matches
-      // the host.
-      //
-      // FIXME: We should also incorporate the detected target features for use
-      // with -native.
-      std::string CPU = llvm::sys::getHostCPUName();
-      if (!CPU.empty() && CPU != "generic")
-        CPUName = Args.MakeArgString(CPU);
-    } else
-      CPUName = A->getValue();
-  }
-
-  // Select the default CPU if none was given (or detection failed).
-  if (!CPUName) {
-    // FIXME: Need target hooks.
-    if (getToolChain().getTriple().isOSDarwin()) {
-      if (getToolChain().getArch() == llvm::Triple::x86_64)
-        CPUName = "core2";
-      else if (getToolChain().getArch() == llvm::Triple::x86)
-        CPUName = "yonah";
-    } else if (getToolChain().getOS().startswith("haiku"))  {
-      if (getToolChain().getArch() == llvm::Triple::x86_64)
-        CPUName = "x86-64";
-      else if (getToolChain().getArch() == llvm::Triple::x86)
-        CPUName = "i586";
-    } else if (getToolChain().getOS().startswith("openbsd"))  {
-      if (getToolChain().getArch() == llvm::Triple::x86_64)
-        CPUName = "x86-64";
-      else if (getToolChain().getArch() == llvm::Triple::x86)
-        CPUName = "i486";
-    } else if (getToolChain().getOS().startswith("bitrig"))  {
-      if (getToolChain().getArch() == llvm::Triple::x86_64)
-        CPUName = "x86-64";
-      else if (getToolChain().getArch() == llvm::Triple::x86)
-        CPUName = "i686";
-    } else if (getToolChain().getOS().startswith("freebsd"))  {
-      if (getToolChain().getArch() == llvm::Triple::x86_64)
-        CPUName = "x86-64";
-      else if (getToolChain().getArch() == llvm::Triple::x86)
-        CPUName = "i486";
-    } else if (getToolChain().getOS().startswith("netbsd"))  {
-      if (getToolChain().getArch() == llvm::Triple::x86_64)
-        CPUName = "x86-64";
-      else if (getToolChain().getArch() == llvm::Triple::x86)
-        CPUName = "i486";
-    } else {
-      if (getToolChain().getArch() == llvm::Triple::x86_64)
-        CPUName = "x86-64";
-      else if (getToolChain().getArch() == llvm::Triple::x86)
-        // All x86 devices running Android have core2 as their common
-        // denominator. This makes a better choice than pentium4.
-        CPUName = isAndroid ? "core2" : "pentium4";
-    }
-  }
-
-  if (CPUName) {
+  if (const char *CPUName = getX86TargetCPU(Args, getToolChain().getTriple())) {
     CmdArgs.push_back("-target-cpu");
     CmdArgs.push_back(CPUName);
   }
@@ -5646,8 +5637,27 @@
     CmdArgs.push_back("-plugin");
     std::string Plugin = ToolChain.getDriver().Dir + "/../lib/LLVMgold.so";
     CmdArgs.push_back(Args.MakeArgString(Plugin));
+
+    // Try to pass driver level flags relevant to LTO code generation down to
+    // the plugin.
+
+    // Handle architecture-specific flags for selecting CPU variants.
+    if (ToolChain.getArch() == llvm::Triple::x86 ||
+        ToolChain.getArch() == llvm::Triple::x86_64)
+      CmdArgs.push_back(
+          Args.MakeArgString(Twine("-plugin-opt=mcpu=") +
+                             getX86TargetCPU(Args, ToolChain.getTriple())));
+    else if (ToolChain.getArch() == llvm::Triple::arm ||
+             ToolChain.getArch() == llvm::Triple::thumb)
+      CmdArgs.push_back(
+          Args.MakeArgString(Twine("-plugin-opt=mcpu=") +
+                             getARMTargetCPU(Args, ToolChain.getTriple())));
+
+    // FIXME: Factor out logic for MIPS, PPC, and other targets to support this
+    // as well.
   }
 
+
   if (Args.hasArg(options::OPT_Z_Xlinker__no_demangle))
     CmdArgs.push_back("--no-demangle");
 
diff --git a/test/Driver/gold-lto.c b/test/Driver/gold-lto.c
index 05ac27a..c2e8bdf 100644
--- a/test/Driver/gold-lto.c
+++ b/test/Driver/gold-lto.c
@@ -1,6 +1,21 @@
 // RUN: touch %t.o
-// RUN: %clang -target x86_64-pc-linux-gnu -### %t.o -O4 -Wl,-plugin-opt=foo 2> %t.log
-// RUN: FileCheck %s < %t.log
-
-// CHECK: "-plugin" "{{.*}}/LLVMgold.so"
-// CHECK: "-plugin-opt=foo"
+//
+// RUN: %clang -target x86_64-unknown-linux -### %t.o -flto 2>&1 \
+// RUN:     -Wl,-plugin-opt=foo \
+// RUN:     | FileCheck %s --check-prefix=CHECK-X86-64-BASIC
+// CHECK-X86-64-BASIC: "-plugin" "{{.*}}/LLVMgold.so"
+// CHECK-X86-64-BASIC: "-plugin-opt=foo"
+//
+// RUN: %clang -target x86_64-unknown-linux -### %t.o -flto 2>&1 \
+// RUN:     -march=corei7 -Wl,-plugin-opt=foo \
+// RUN:     | FileCheck %s --check-prefix=CHECK-X86-64-COREI7
+// CHECK-X86-64-COREI7: "-plugin" "{{.*}}/LLVMgold.so"
+// CHECK-X86-64-COREI7: "-plugin-opt=mcpu=corei7"
+// CHECK-X86-64-COREI7: "-plugin-opt=foo"
+//
+// RUN: %clang -target arm-unknown-linux -### %t.o -flto 2>&1 \
+// RUN:     -march=armv7a -Wl,-plugin-opt=foo \
+// RUN:     | FileCheck %s --check-prefix=CHECK-ARM-V7A
+// CHECK-ARM-V7A: "-plugin" "{{.*}}/LLVMgold.so"
+// CHECK-ARM-V7A: "-plugin-opt=mcpu=cortex-a8"
+// CHECK-ARM-V7A: "-plugin-opt=foo"