Index: llvm/test/tools/llvm-ar/response-utf8.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-ar/response-utf8.test
@@ -0,0 +1,8 @@
+## Check that response files can cope with non-ascii characters.
+
+# RUN: llvm-ar r %t.a %s
+
+# RUN: echo "r %t-£.a %s" > %t-non-ascii.txt
+# RUN: llvm-ar @%t-non-ascii.txt
+## Work-around diff not working with non-ascii filenames on windows.
+RUN: env LANG=en_US.UTF-8 %python -c "assert open(ur'%t-\U000000A3.a', 'rb').read() == open(r'%t.a', 'rb').read()"
Index: llvm/test/tools/llvm-ar/response.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-ar/response.test
@@ -0,0 +1,35 @@
+## llvm-ar should be able to consume response files.
+
+# RUN: echo contents > %t.txt
+# RUN: echo rc %t1.a %t.txt > %t.response1.txt
+# RUN: llvm-ar @%t.response1.txt
+# RUN: llvm-ar p %t1.a | FileCheck %s --check-prefix=CONTENTS
+
+## Quotes and Spaces.
+# RUN: echo contents > "%t space.txt"
+## Python is used here to ensure the quotes are written to the response file
+# RUN: %python -c "import os; open(r'%t.response2.txt', 'wb').write(r'%t2.a \"%t space.txt\"'+ '\n')"
+# RUN: llvm-ar rc @%t.response2.txt
+# RUN: llvm-ar p %t2.a | FileCheck %s --check-prefix=CONTENTS
+
+## Arguments after the response file.
+# RUN: echo rc %t3.a > %t.response3.txt
+# RUN: llvm-ar @%t.response3.txt %t.txt
+# RUN: llvm-ar p %t3.a | FileCheck %s --check-prefix=CONTENTS
+
+# CONTENTS: contents
+
+## rsp-quoting
+# RUN: not llvm-ar --rsp-quoting=foobar @t.response1.txt 2>&1 | \
+# RUN: FileCheck  %s --check-prefix=ERROR
+# ERROR: Invalid response file quoting style foobar
+
+# RUN: echo "rc %t.a blah\foo" > %t-rsp.txt
+# RUN: not llvm-ar --rsp-quoting=windows @%t-rsp.txt 2>&1 | \
+# RUN: FileCheck %s --check-prefix=WIN
+# WIN: error: blah\foo: no such file or directory
+
+# RUN: echo "rc %t.a blah\foo" > %t-rsp.txt
+# RUN: not llvm-ar -rsp-quoting=posix @%t-rsp.txt 2>&1 | \
+# RUN:  FileCheck %s --check-prefix=POSIX
+# POSIX: error: blahfoo: no such file or directory
Index: llvm/tools/llvm-ar/llvm-ar.cpp
===================================================================
--- llvm/tools/llvm-ar/llvm-ar.cpp
+++ llvm/tools/llvm-ar/llvm-ar.cpp
@@ -80,6 +80,10 @@
     =bsd                -   bsd
   --plugin=<string>     - ignored for compatibility
   -h --help             - display this help and exit
+  --rsp-quoting         - quoting style for response files
+    =default            -   default
+    =posix              -   posix
+    =windows            -   windows
   --version             - print the version and exit
   @<file>               - read options from <file>
 
@@ -259,6 +263,37 @@
   PositionalArgs.erase(PositionalArgs.begin());
 }
 
+static cl::TokenizerCallback getRspQuoting(SmallVector<const char *, 0> &Argv) {
+  cl::TokenizerCallback Default =
+      Triple(sys::getProcessTriple()).getOS() == Triple::Win32
+          ? cl::TokenizeWindowsCommandLine
+          : cl::TokenizeGNUCommandLine;
+
+  cl::TokenizerCallback Ret = Default;
+  size_t j = 1;
+
+  for (size_t i = 1; i < Argv.size(); ++i) {
+    StringRef Arg = Argv[i];
+    if (Arg.startswith("-rsp-quoting=") || Arg.startswith("--rsp-quoting=")) {
+
+      StringRef Match = Arg.split("=").second;
+      if (Match == "posix")
+        Ret = cl::TokenizeGNUCommandLine;
+      else if (Match == "windows")
+        Ret = cl::TokenizeWindowsCommandLine;
+      else if (Match == "default")
+        Ret = Default;
+      else
+        fail(std::string("Invalid response file quoting style ") + Match);
+
+    } else
+      Argv[j++] = Argv[i];
+  }
+
+  Argv.set_size(j);
+  return Ret;
+}
+
 static object::Archive &readLibrary(const Twine &Library) {
   auto BufOrErr = MemoryBuffer::getFile(Library, -1, false);
   failIfError(BufOrErr.getError(), "could not open library " + Library);
@@ -1096,7 +1131,8 @@
 static int ar_main(int argc, char **argv) {
   SmallVector<const char *, 0> Argv(argv, argv + argc);
   StringSaver Saver(Alloc);
-  cl::ExpandResponseFiles(Saver, cl::TokenizeGNUCommandLine, Argv);
+
+  cl::ExpandResponseFiles(Saver, getRspQuoting(Argv), Argv);
   for (size_t i = 1; i < Argv.size(); ++i) {
     StringRef Arg = Argv[i];
     const char *match = nullptr;