Index: test/MinGW/driver.test
===================================================================
--- test/MinGW/driver.test
+++ test/MinGW/driver.test
@@ -4,6 +4,9 @@
 X86-SAME: -alternatename:__image_base__=___ImageBase
 X86-SAME: foo.o
 
+RUN: echo "-### foo.o -m i386pe" > %t.rsp
+RUN: ld.lld @%t.rsp | FileCheck -check-prefix=X86 %s
+
 RUN: ld.lld -### foo.o -m i386pep | FileCheck -check-prefix=X64 %s
 X64:      -out:a.exe
 X64-SAME: -machine:x64
Index: tools/lld/lld.cpp
===================================================================
--- tools/lld/lld.cpp
+++ tools/lld/lld.cpp
@@ -26,9 +26,13 @@
 //===----------------------------------------------------------------------===//
 
 #include "lld/Common/Driver.h"
+#include "lld/Common/Memory.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/ADT/Twine.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/Path.h"
 #include <cstdlib>
@@ -59,7 +63,7 @@
       .Default(Invalid);
 }
 
-static bool isPETarget(const std::vector<const char *> &V) {
+static bool isPETarget(const SmallVector<const char *, 256> &V) {
   for (auto It = V.begin(); It + 1 != V.end(); ++It) {
     if (StringRef(*It) != "-m")
       continue;
@@ -110,6 +114,12 @@
   return parseProgname(Arg0);
 }
 
+static cl::TokenizerCallback getDefaultQuotingStyle() {
+  if (Triple(sys::getProcessTriple()).getOS() == Triple::Win32)
+    return cl::TokenizeWindowsCommandLine;
+  return cl::TokenizeGNUCommandLine;
+}
+
 // If this function returns true, lld calls _exit() so that it quickly
 // exits without invoking destructors of globally allocated objects.
 //
@@ -125,10 +135,16 @@
 
   std::vector<const char *> Args(Argv, Argv + Argc);
   switch (parseFlavor(Args)) {
-  case Gnu:
-    if (isPETarget(Args))
-      return !mingw::link(Args);
+  case Gnu: {
+    // Expand response files (arguments in the form of @<filename>)
+    // to allow deducing the PE -m argument from arguments in them.
+    SmallVector<const char *, 256> ExpandedArgs(Args.data(),
+                                                Args.data() + Args.size());
+    cl::ExpandResponseFiles(Saver, getDefaultQuotingStyle(), ExpandedArgs);
+    if (isPETarget(ExpandedArgs))
+      return !mingw::link(ExpandedArgs);
     return !elf::link(Args, canExitEarly());
+  }
   case WinLink:
     return !coff::link(Args, canExitEarly());
   case Darwin: