Index: lib/Frontend/DependencyFile.cpp
===================================================================
--- lib/Frontend/DependencyFile.cpp
+++ lib/Frontend/DependencyFile.cpp
@@ -386,28 +386,32 @@
 /// for Windows file-naming info.
 static void PrintFilename(raw_ostream &OS, StringRef Filename,
                           DependencyOutputFormat OutputFormat) {
+  // Convert filename to platform native path
+  llvm::SmallString<256> NativePath;
+  llvm::sys::path::native(Filename.str(), NativePath);
+
   if (OutputFormat == DependencyOutputFormat::NMake) {
     // Add quotes if needed. These are the characters listed as "special" to
     // NMake, that are legal in a Windows filespec, and that could cause
     // misinterpretation of the dependency string.
-    if (Filename.find_first_of(" #${}^!") != StringRef::npos)
-      OS << '\"' << Filename << '\"';
+    if (NativePath.find_first_of(" #${}^!") != StringRef::npos)
+      OS << '\"' << NativePath << '\"';
     else
-      OS << Filename;
+      OS << NativePath;
     return;
   }
   assert(OutputFormat == DependencyOutputFormat::Make);
-  for (unsigned i = 0, e = Filename.size(); i != e; ++i) {
-    if (Filename[i] == '#') // Handle '#' the broken gcc way.
+  for (unsigned i = 0, e = NativePath.size(); i != e; ++i) {
+    if (NativePath[i] == '#') // Handle '#' the broken gcc way.
       OS << '\\';
-    else if (Filename[i] == ' ') { // Handle space correctly.
+    else if (NativePath[i] == ' ') { // Handle space correctly.
       OS << '\\';
       unsigned j = i;
-      while (j > 0 && Filename[--j] == '\\')
+      while (j > 0 && NativePath[--j] == '\\')
         OS << '\\';
-    } else if (Filename[i] == '$') // $ is escaped by $$.
+    } else if (NativePath[i] == '$') // $ is escaped by $$.
       OS << '$';
-    OS << Filename[i];
+    OS << NativePath[i];
   }
 }
 
Index: test/Frontend/dependency-gen-escaping.c
===================================================================
--- test/Frontend/dependency-gen-escaping.c
+++ test/Frontend/dependency-gen-escaping.c
@@ -21,7 +21,7 @@
 // Backslash followed by # or space should escape both characters, because
 // that's what GNU Make wants.  GCC does the right thing with space, but not
 // #, so Clang does too. (There should be 3 backslashes before the #.)
-// SEP2F: a\b\\#c\\\ d.h
+// SEP2F: a{{[/\\]}}b{{[/\\]}}\#c{{/|\\\\}}\ d.h
 // With -fms-compatibility, Backslashes in #include are treated as path separators.
 // Backslashes are given in the emission for special characters, like 0x20 or 0x23.
 // SEP5C: a{{[/\\]}}b{{[/\\]}}\#c{{/|\\\\}}\ d.h
Index: test/Frontend/dependency-gen.c
===================================================================
--- test/Frontend/dependency-gen.c
+++ test/Frontend/dependency-gen.c
@@ -4,19 +4,19 @@
 // RUN: echo > %t.dir/a/b/x.h
 // RUN: cd %t.dir
 // RUN: %clang -MD -MF - %s -fsyntax-only -I a/b | FileCheck -check-prefix=CHECK-ONE %s
-// CHECK-ONE: {{ }}a/b{{[/\\]}}x.h
+// CHECK-ONE: {{ }}a{{[/\\]}}b{{[/\\]}}x.h
 
 // PR8974 (-include flag)
 // RUN: %clang -MD -MF - %s -fsyntax-only -include a/b/x.h -DINCLUDE_FLAG_TEST | FileCheck -check-prefix=CHECK-TWO %s
-// CHECK-TWO: {{ }}a/b/x.h
+// CHECK-TWO: {{ }}a{{[/\\]}}b{{[/\\]}}x.h
 
 // rdar://problem/9734352 (paths involving ".")
 // RUN: %clang -MD -MF - %s -fsyntax-only -I ./a/b | FileCheck -check-prefix=CHECK-THREE %s
-// CHECK-THREE: {{ }}a/b{{[/\\]}}x.h
+// CHECK-THREE: {{ }}a{{[/\\]}}b{{[/\\]}}x.h
 // RUN: %clang -MD -MF - %s -fsyntax-only -I .//./a/b/ | FileCheck -check-prefix=CHECK-FOUR %s
-// CHECK-FOUR: {{ }}a/b{{[/\\]}}x.h
+// CHECK-FOUR: {{ }}a{{[/\\]}}b{{[/\\]}}x.h
 // RUN: %clang -MD -MF - %s -fsyntax-only -I a/b/. | FileCheck -check-prefix=CHECK-FIVE %s
-// CHECK-FIVE: {{ }}a/b/.{{[/\\]}}x.h
+// CHECK-FIVE: {{ }}a{{[/\\]}}b{{[/\\]}}.{{[/\\]}}x.h
 // RUN: cd a/b
 // RUN: %clang -MD -MF - %s -fsyntax-only -I ./ | FileCheck -check-prefix=CHECK-SIX %s
 // CHECK-SIX: {{ }}x.h
Index: test/Modules/relative-dep-gen.cpp
===================================================================
--- test/Modules/relative-dep-gen.cpp
+++ test/Modules/relative-dep-gen.cpp
@@ -30,9 +30,9 @@
 #include "Inputs/relative-dep-gen-1.h"
 
 // CHECK-BUILD: mod.pcm:
-// CHECK-BUILD:   {{[ \t]}}Inputs/relative-dep-gen{{(-cwd)?}}.modulemap
-// CHECK-BUILD:   {{[ \t]}}Inputs/relative-dep-gen-1.h
-// CHECK-BUILD:   {{[ \t]}}Inputs/relative-dep-gen-2.h
+// CHECK-BUILD:   {{[ \t]}}Inputs{{[/\\]}}relative-dep-gen{{(-cwd)?}}.modulemap
+// CHECK-BUILD:   {{[ \t]}}Inputs{{[/\\]}}relative-dep-gen-1.h
+// CHECK-BUILD:   {{[ \t]}}Inputs{{[/\\]}}relative-dep-gen-2.h
 // CHECK-USE: use.o:
 // CHECK-USE-DAG:   {{[ \t]}}relative-dep-gen.cpp
 // CHECK-EXPLICIT-DAG:   mod.pcm