diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index d11fa4ea79f3..174df12c19fd 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -83,6 +83,23 @@ static void CheckCodeGenerationOptions(const Driver &D, const ArgList &Args) {
         << A->getAsString(Args) << "-static";
 }
 
+// Add backslashes to escape spaces and other backslashes.
+// This is used for the space-separated argument list specified with
+// the -dwarf-debug-flags option.
+static void EscapeSpacesAndBackslashes(const char *Arg,
+                                       SmallVectorImpl<char> &Res) {
+  for ( ; *Arg; ++Arg) {
+    switch (*Arg) {
+    default: break;
+    case ' ':
+    case '\\':
+      Res.push_back('\\');
+      break;
+    }
+    Res.push_back(*Arg);
+  }
+}
+
 // Quote target names for inclusion in GNU Make dependency files.
 // Only the characters '$', '#', ' ', '\t' are quoted.
 static void QuoteTarget(StringRef Target,
@@ -4465,8 +4482,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     SmallString<256> Flags;
     Flags += Exec;
     for (unsigned i = 0, e = OriginalArgs.size(); i != e; ++i) {
+      SmallString<128> EscapedArg;
+      EscapeSpacesAndBackslashes(OriginalArgs[i], EscapedArg);
       Flags += " ";
-      Flags += OriginalArgs[i];
+      Flags += EscapedArg;
     }
     CmdArgs.push_back("-dwarf-debug-flags");
     CmdArgs.push_back(Args.MakeArgString(Flags.str()));
@@ -4896,8 +4915,10 @@ void ClangAs::ConstructJob(Compilation &C, const JobAction &JA,
     const char *Exec = getToolChain().getDriver().getClangProgramPath();
     Flags += Exec;
     for (unsigned i = 0, e = OriginalArgs.size(); i != e; ++i) {
+      SmallString<128> EscapedArg;
+      EscapeSpacesAndBackslashes(OriginalArgs[i], EscapedArg);
       Flags += " ";
-      Flags += OriginalArgs[i];
+      Flags += EscapedArg;
     }
     CmdArgs.push_back("-dwarf-debug-flags");
     CmdArgs.push_back(Args.MakeArgString(Flags.str()));
diff --git a/clang/test/Driver/darwin-debug-flags.c b/clang/test/Driver/darwin-debug-flags.c
index f98e9ce7bd8c..20f1bbcfd6d0 100644
--- a/clang/test/Driver/darwin-debug-flags.c
+++ b/clang/test/Driver/darwin-debug-flags.c
@@ -1,4 +1,4 @@
-// RUN: env RC_DEBUG_OPTIONS=1 %clang -target i386-apple-darwin9 -g -Os %s  -emit-llvm -S -o - | FileCheck %s
+// RUN: env RC_DEBUG_OPTIONS=1 %clang -target i386-apple-darwin9 -I "path with \spaces" -g -Os %s  -emit-llvm -S -o - | FileCheck %s
 // <rdar://problem/7256886>
 // RUN: touch %t.s
 // RUN: env RC_DEBUG_OPTIONS=1 %clang -### -target i386-apple-darwin9 -c -g %t.s 2>&1 | FileCheck -check-prefix=S %s
@@ -6,6 +6,7 @@
 // RUN: %clang -### -target i386-apple-darwin9 -c -g %t.s 2>&1 | FileCheck -check-prefix=P %s
 
 // CHECK: !0 = metadata !{
+// CHECK: -I path\5C with\5C \5C\5Cspaces
 // CHECK: -g -Os
 // CHECK: -mmacosx-version-min=10.5.0
 // CHECK: [ DW_TAG_compile_unit ]