diff --git a/clang/lib/Driver/CMakeLists.txt b/clang/lib/Driver/CMakeLists.txt
index dfc6e091f992..412840b6ea6e 100644
--- a/clang/lib/Driver/CMakeLists.txt
+++ b/clang/lib/Driver/CMakeLists.txt
@@ -6,6 +6,7 @@ set(LLVM_LINK_COMPONENTS
 add_clang_library(clangDriver
   Action.cpp
   Compilation.cpp
+  CrossWindowsToolChain.cpp
   Driver.cpp
   DriverOptions.cpp
   Job.cpp
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 9fea2f405cd8..cb75f2ccebe2 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -2039,6 +2039,9 @@ const ToolChain &Driver::getToolChain(const ArgList &Args,
         else
           TC = new toolchains::Generic_GCC(*this, Target, Args);
         break;
+      case llvm::Triple::Itanium:
+        TC = new toolchains::CrossWindowsToolChain(*this, Target, Args);
+        break;
       case llvm::Triple::MSVC:
       case llvm::Triple::UnknownEnvironment:
         TC = new toolchains::MSVCToolChain(*this, Target, Args);
diff --git a/clang/lib/Driver/ToolChains.h b/clang/lib/Driver/ToolChains.h
index 525a7d29a4f4..d8059583563d 100644
--- a/clang/lib/Driver/ToolChains.h
+++ b/clang/lib/Driver/ToolChains.h
@@ -761,6 +761,34 @@ protected:
   Tool *buildAssembler() const override;
 };
 
+class LLVM_LIBRARY_VISIBILITY CrossWindowsToolChain : public Generic_GCC {
+public:
+  CrossWindowsToolChain(const Driver &D, const llvm::Triple &T,
+                        const llvm::opt::ArgList &Args);
+
+  bool IsIntegratedAssemblerDefault() const override { return true; }
+  bool IsUnwindTablesDefault() const override;
+  bool isPICDefault() const override;
+  bool isPIEDefault() const override;
+  bool isPICDefaultForced() const override;
+
+  unsigned int GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
+    return 0;
+  }
+
+  void AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                                 llvm::opt::ArgStringList &CC1Args)
+      const override;
+  void AddClangCXXStdlibIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                                    llvm::opt::ArgStringList &CC1Args)
+      const override;
+  void AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
+                           llvm::opt::ArgStringList &CmdArgs) const override;
+
+protected:
+  Tool *buildLinker() const override;
+  Tool *buildAssembler() const override;
+};
 
 class LLVM_LIBRARY_VISIBILITY XCore : public ToolChain {
 public:
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 4a125f5a9da9..e34fd5c9e43c 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2138,6 +2138,14 @@ static void addClangRTLinux(
     CmdArgs.push_back("-lgcc_eh");
 }
 
+static void addClangRTWindows(const ToolChain &TC, const ArgList &Args,
+                              ArgStringList &CmdArgs) {
+  SmallString<128> LibClangRT = getCompilerRTLibDir(TC);
+  llvm::sys::path::append(LibClangRT, Twine("libclang_rt.builtins-") +
+                          getArchNameForCompilerRTLib(TC) + ".lib");
+  CmdArgs.push_back(Args.MakeArgString(LibClangRT));
+}
+
 static void addProfileRT(
     const ToolChain &TC, const ArgList &Args, ArgStringList &CmdArgs) {
   if (!(Args.hasFlag(options::OPT_fprofile_arcs, options::OPT_fno_profile_arcs,
@@ -7288,7 +7296,15 @@ static void AddRunTimeLibs(const ToolChain &TC, const Driver &D,
 
   switch(RLT) {
   case ToolChain::RLT_CompilerRT:
-    addClangRTLinux(TC, Args, CmdArgs);
+    switch (TC.getTriple().getOS()) {
+    default: llvm_unreachable("unsupported OS");
+    case llvm::Triple::Win32:
+      addClangRTWindows(TC, Args, CmdArgs);
+      break;
+    case llvm::Triple::Linux:
+      addClangRTLinux(TC, Args, CmdArgs);
+      break;
+    }
     break;
   case ToolChain::RLT_Libgcc:
     AddLibgcc(TC.getTriple(), D, CmdArgs, Args);
@@ -8114,3 +8130,181 @@ void XCore::Link::ConstructJob(Compilation &C, const JobAction &JA,
   const char *Exec = Args.MakeArgString(getToolChain().GetProgramPath("xcc"));
   C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs));
 }
+
+void CrossWindows::Assemble::ConstructJob(Compilation &C, const JobAction &JA,
+                                          const InputInfo &Output,
+                                          const InputInfoList &Inputs,
+                                          const ArgList &Args,
+                                          const char *LinkingOutput) const {
+  const auto &TC =
+      static_cast<const toolchains::CrossWindowsToolChain &>(getToolChain());
+  ArgStringList CmdArgs;
+  const char *Exec;
+
+  switch (TC.getArch()) {
+  default: llvm_unreachable("unsupported architecture");
+  case llvm::Triple::arm:
+  case llvm::Triple::thumb:
+    break;
+  case llvm::Triple::x86:
+    CmdArgs.push_back("--32");
+    break;
+  case llvm::Triple::x86_64:
+    CmdArgs.push_back("--64");
+    break;
+  }
+
+  Args.AddAllArgValues(CmdArgs, options::OPT_Wa_COMMA, options::OPT_Xassembler);
+
+  CmdArgs.push_back("-o");
+  CmdArgs.push_back(Output.getFilename());
+
+  for (const auto &Input : Inputs)
+    CmdArgs.push_back(Input.getFilename());
+
+  const std::string Assembler = TC.GetProgramPath("as");
+  Exec = Args.MakeArgString(Assembler);
+
+  C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs));
+}
+
+void CrossWindows::Link::ConstructJob(Compilation &C, const JobAction &JA,
+                                      const InputInfo &Output,
+                                      const InputInfoList &Inputs,
+                                      const ArgList &Args,
+                                      const char *LinkingOutput) const {
+  const auto &TC =
+      static_cast<const toolchains::CrossWindowsToolChain &>(getToolChain());
+  const llvm::Triple &T = TC.getTriple();
+  const Driver &D = TC.getDriver();
+  SmallString<128> EntryPoint;
+  ArgStringList CmdArgs;
+  const char *Exec;
+
+  // Silence warning for "clang -g foo.o -o foo"
+  Args.ClaimAllArgs(options::OPT_g_Group);
+  // and "clang -emit-llvm foo.o -o foo"
+  Args.ClaimAllArgs(options::OPT_emit_llvm);
+  // and for "clang -w foo.o -o foo"
+  Args.ClaimAllArgs(options::OPT_w);
+  // Other warning options are already handled somewhere else.
+
+  if (!D.SysRoot.empty())
+    CmdArgs.push_back(Args.MakeArgString("--sysroot=" + D.SysRoot));
+
+  if (Args.hasArg(options::OPT_pie))
+    CmdArgs.push_back("-pie");
+  if (Args.hasArg(options::OPT_rdynamic))
+    CmdArgs.push_back("-export-dynamic");
+  if (Args.hasArg(options::OPT_s))
+    CmdArgs.push_back("--strip-all");
+
+  CmdArgs.push_back("-m");
+  switch (TC.getArch()) {
+  default: llvm_unreachable("unsupported architecture");
+  case llvm::Triple::arm:
+  case llvm::Triple::thumb:
+    // FIXME: this is incorrect for WinCE
+    CmdArgs.push_back("thumb2pe");
+    break;
+  case llvm::Triple::x86:
+    CmdArgs.push_back("i386pe");
+    EntryPoint.append("_");
+    break;
+  case llvm::Triple::x86_64:
+    CmdArgs.push_back("i386pep");
+    break;
+  }
+
+  if (Args.hasArg(options::OPT_shared)) {
+    switch (T.getArch()) {
+    default: llvm_unreachable("unsupported architecture");
+    case llvm::Triple::arm:
+    case llvm::Triple::thumb:
+    case llvm::Triple::x86_64:
+      EntryPoint.append("_DllMainCRTStartup");
+      break;
+    case llvm::Triple::x86:
+      EntryPoint.append("_DllMainCRTStartup@12");
+      break;
+    }
+
+    CmdArgs.push_back("-shared");
+    CmdArgs.push_back("-Bdynamic");
+
+    CmdArgs.push_back("--enable-auto-image-base");
+
+    CmdArgs.push_back("--entry");
+    CmdArgs.push_back(Args.MakeArgString(EntryPoint));
+  } else {
+    EntryPoint.append("mainCRTStartup");
+
+    CmdArgs.push_back(Args.hasArg(options::OPT_static) ? "-Bstatic"
+                                                       : "-Bdynamic");
+
+    if (!Args.hasArg(options::OPT_nostdlib) &&
+        !Args.hasArg(options::OPT_nostartfiles)) {
+      CmdArgs.push_back("--entry");
+      CmdArgs.push_back(Args.MakeArgString(EntryPoint));
+    }
+
+    // FIXME: handle subsystem
+  }
+
+  // NOTE: deal with multiple definitions on Windows (e.g. COMDAT)
+  CmdArgs.push_back("--allow-multiple-definitions");
+
+  CmdArgs.push_back("-o");
+  CmdArgs.push_back(Output.getFilename());
+
+  if (Args.hasArg(options::OPT_shared) || Args.hasArg(options::OPT_rdynamic)) {
+    SmallString<261> ImpLib(Output.getFilename());
+    llvm::sys::path::replace_extension(ImpLib, ".lib");
+
+    CmdArgs.push_back("--out-implib");
+    CmdArgs.push_back(Args.MakeArgString(ImpLib));
+  }
+
+  if (!Args.hasArg(options::OPT_nostdlib) &&
+      !Args.hasArg(options::OPT_nostartfiles)) {
+    const std::string CRTPath(D.SysRoot + "/usr/lib/");
+    const char *CRTBegin;
+
+    CRTBegin =
+        Args.hasArg(options::OPT_shared) ? "crtbeginS.obj" : "crtbegin.obj";
+    CmdArgs.push_back(Args.MakeArgString(CRTPath + CRTBegin));
+  }
+
+  Args.AddAllArgs(CmdArgs, options::OPT_L);
+
+  const auto &Paths = TC.getFilePaths();
+  for (const auto &Path : Paths)
+    CmdArgs.push_back(Args.MakeArgString(StringRef("-L") + Path));
+
+  AddLinkerInputs(TC, Inputs, Args, CmdArgs);
+
+  if (D.CCCIsCXX() && !Args.hasArg(options::OPT_nostdlib) &&
+      !Args.hasArg(options::OPT_nodefaultlibs)) {
+    bool StaticCXX = Args.hasArg(options::OPT_static_libstdcxx) &&
+                     !Args.hasArg(options::OPT_static);
+    if (StaticCXX)
+      CmdArgs.push_back("-Bstatic");
+    TC.AddCXXStdlibLibArgs(Args, CmdArgs);
+    if (StaticCXX)
+      CmdArgs.push_back("-Bdynamic");
+  }
+
+  if (!Args.hasArg(options::OPT_nostdlib)) {
+    if (!Args.hasArg(options::OPT_nodefaultlibs)) {
+      // TODO handle /MT[d] /MD[d]
+      CmdArgs.push_back("-lmsvcrt");
+      AddRunTimeLibs(TC, D, CmdArgs, Args);
+    }
+  }
+
+  const std::string Linker = TC.GetProgramPath("ld");
+  Exec = Args.MakeArgString(Linker);
+
+  C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs));
+}
+
diff --git a/clang/lib/Driver/Tools.h b/clang/lib/Driver/Tools.h
index 8ab145652bb7..59af8a0ec978 100644
--- a/clang/lib/Driver/Tools.h
+++ b/clang/lib/Driver/Tools.h
@@ -645,6 +645,32 @@ namespace XCore {
   };
 } // end namespace XCore.
 
+namespace CrossWindows {
+class LLVM_LIBRARY_VISIBILITY Assemble : public Tool {
+public:
+  Assemble(const ToolChain &TC) : Tool("CrossWindows::Assemble", "as", TC) { }
+
+  bool hasIntegratedCPP() const override { return false; }
+
+  void ConstructJob(Compilation &C, const JobAction &JA,
+                    const InputInfo &Output, const InputInfoList &Inputs,
+                    const llvm::opt::ArgList &TCArgs,
+                    const char *LinkingOutput) const override;
+};
+
+class LLVM_LIBRARY_VISIBILITY Link : public Tool {
+public:
+  Link(const ToolChain &TC) : Tool("CrossWindows::Link", "ld", TC, RF_Full) {}
+
+  bool hasIntegratedCPP() const override { return false; }
+  bool isLinkJob() const override { return true; }
+
+  void ConstructJob(Compilation &C, const JobAction &JA,
+                    const InputInfo &Output, const InputInfoList &Inputs,
+                    const llvm::opt::ArgList &TCArgs,
+                    const char *LinkingOutput) const override;
+};
+}
 
 } // end namespace toolchains
 } // end namespace driver
diff --git a/clang/test/Driver/windows-cross.c b/clang/test/Driver/windows-cross.c
new file mode 100644
index 000000000000..6fe3a36908b3
--- /dev/null
+++ b/clang/test/Driver/windows-cross.c
@@ -0,0 +1,40 @@
+// RUN: %clang -### -target armv7-windows-itanium -o /dev/null %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix CHECK-BASIC
+
+// CHECK-BASIC: ld" "-m" "thumb2pe" "-Bdynamic" "--entry" "mainCRTStartup" "--allow-multiple-definitions" "-o" "/dev/null" "/usr/lib/crtbegin.obj" "-L/usr/lib" "-L/usr/lib/gcc" "{{.*}}.o" "-lmsvcrt" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed"
+
+// RUN: %clang -### -target armv7-windows-itanium -rtlib=compiler-rt -o /dev/null %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix CHECK-RTLIB
+
+// CHECK-RTLIB: ld" "-m" "thumb2pe" "-Bdynamic" "--entry" "mainCRTStartup" "--allow-multiple-definitions" "-o" "/dev/null" "/usr/lib/crtbegin.obj" "-L/usr/lib" "-L/usr/lib/gcc" "{{.*}}.o" "-lmsvcrt" "{{.*}}/libclang_rt.builtins-arm.lib"
+
+// RUN: %clang -### -target armv7-windows-itanium --sysroot /sysroot/Windows/ARM/8.1 -rtlib=compiler-rt -o /dev/null %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix CHECK-SYSROOT
+
+// CHECK-SYSROOT: ld" "--sysroot=/sysroot/Windows/ARM/8.1" "-m" "thumb2pe" "-Bdynamic" "--entry" "mainCRTStartup" "--allow-multiple-definitions" "-o" "/dev/null" "/sysroot/Windows/ARM/8.1/usr/lib/crtbegin.obj" "-L/sysroot/Windows/ARM/8.1/usr/lib" "-L/sysroot/Windows/ARM/8.1/usr/lib/gcc" "{{.*}}.o" "-lmsvcrt" "{{.*}}/libclang_rt.builtins-arm.lib"
+
+// RUN: %clang -### -target armv7-windows-itanium --sysroot /sysroot/Windows/ARM/8.1 -rtlib=compiler-rt -stdlib=libc++ -o /dev/null %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix CHECK-C-LIBCXX
+
+// CHECK-C-LIBCXX: ld" "--sysroot=/sysroot/Windows/ARM/8.1" "-m" "thumb2pe" "-Bdynamic" "--entry" "mainCRTStartup" "--allow-multiple-definitions" "-o" "/dev/null" "/sysroot/Windows/ARM/8.1/usr/lib/crtbegin.obj" "{{.*}}.o" "-lmsvcrt" "{{.*}}/libclang_rt.builtins-arm.lib"
+
+// RUN: %clangxx -### -target armv7-windows-itanium --sysroot /sysroot/Windows/ARM/8.1 -rtlib=compiler-rt -stdlib=libc++ -o /dev/null %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix CHECK-LIBCXX
+
+// CHECK-LIBCXX: ld" "--sysroot=/sysroot/Windows/ARM/8.1" "-m" "thumb2pe" "-Bdynamic" "--entry" "mainCRTStartup" "--allow-multiple-definitions" "-o" "/dev/null" "/sysroot/Windows/ARM/8.1/usr/lib/crtbegin.obj" "{{.*}}.o" "-lc++" "-lmsvcrt" "{{.*}}/libclang_rt.builtins-arm.lib"
+
+// RUN: %clang -### -target armv7-windows-itanium --sysroot /sysroot/Windows/ARM/8.1 -shared -rtlib=compiler-rt -stdlib=libc++ -o shared.dll %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix CHECK-SHARED
+
+// CHECK-SHARED: ld" "--sysroot=/sysroot/Windows/ARM/8.1" "-m" "thumb2pe" "-shared" "-Bdynamic" "--enable-auto-image-base" "--entry" "_DllMainCRTStartup" "--allow-multiple-definitions" "-o" "shared.dll" "--out-implib" "shared.lib" "/sysroot/Windows/ARM/8.1/usr/lib/crtbeginS.obj" "{{.*}}.o" "-lmsvcrt" "{{.*}}/libclang_rt.builtins-arm.lib"
+
+// RUN: %clang -### -target armv7-windows-itanium --sysroot /sysroot/Windows/ARM/8.1 -shared -rtlib=compiler-rt -stdlib=libc++ -nostartfiles -o shared.dll %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix CHECK-NOSTARTFILES
+
+// CHECK-NOSTARTFILES: ld" "--sysroot=/sysroot/Windows/ARM/8.1" "-m" "thumb2pe" "-shared" "-Bdynamic" "--enable-auto-image-base" "--entry" "_DllMainCRTStartup" "--allow-multiple-definitions" "-o" "shared.dll" "--out-implib" "shared.lib" "{{.*}}.o" "-lmsvcrt" "{{.*}}/libclang_rt.builtins-arm.lib"
+
+// RUN: %clang -### -target armv7-windows-itanium --sysroot /sysroot/Windows/ARM/8.1 -shared -rtlib=compiler-rt -stdlib=libc++ -nostartfiles -nodefaultlibs -o shared.dll %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix CHECK-STANDALONE
+
+// CHECK-STANDALONE: ld" "--sysroot=/sysroot/Windows/ARM/8.1" "-m" "thumb2pe" "-shared" "-Bdynamic" "--enable-auto-image-base" "--entry" "_DllMainCRTStartup" "--allow-multiple-definitions" "-o" "shared.dll" "--out-implib" "shared.lib" "{{.*}}.o"
+