Index: lib/Support/GraphWriter.cpp
===================================================================
--- lib/Support/GraphWriter.cpp
+++ lib/Support/GraphWriter.cpp
@@ -189,7 +189,13 @@
     return ExecGraphViewer(ViewerPath, args, Filename, wait, ErrMsg);
   }
 
-  enum PSViewerKind { PSV_None, PSV_OSXOpen, PSV_XDGOpen, PSV_Ghostview };
+  enum PSViewerKind {
+    PSV_None,
+    PSV_OSXOpen,
+    PSV_XDGOpen,
+    PSV_Ghostview,
+    PDFV_Start
+  };
   PSViewerKind PSViewer = PSV_None;
 #ifdef __APPLE__
   if (!PSViewer && S.TryFindProgram("open", ViewerPath))
@@ -199,17 +205,26 @@
     PSViewer = PSV_Ghostview;
   if (!PSViewer && S.TryFindProgram("xdg-open", ViewerPath))
     PSViewer = PSV_XDGOpen;
+#ifdef LLVM_ON_WIN32
+  if (!PSViewer && S.TryFindProgram("cmd", ViewerPath)) {
+    PSViewer = PDFV_Start;
+  }
+#endif
 
   // PostScript graph generator + PostScript viewer
   std::string GeneratorPath;
   if (PSViewer &&
       (S.TryFindProgram(getProgramName(program), GeneratorPath) ||
        S.TryFindProgram("dot|fdp|neato|twopi|circo", GeneratorPath))) {
-    std::string PSFilename = Filename + ".ps";
+    std::string PSFilename =
+        Filename + (PSViewer == PDFV_Start ? ".pdf" : ".ps");
 
     std::vector<const char *> args;
     args.push_back(GeneratorPath.c_str());
-    args.push_back("-Tps");
+    if (PSViewer == PDFV_Start)
+      args.push_back("-Tpdf");
+    else
+      args.push_back("-Tps");
     args.push_back("-Nfontname=Courier");
     args.push_back("-Gsize=7.5,10");
     args.push_back(Filename.c_str());
@@ -222,6 +237,10 @@
     if (ExecGraphViewer(GeneratorPath, args, Filename, true, ErrMsg))
       return true;
 
+    std::string StartArg;
+    if (PSViewer == PDFV_Start)
+      StartArg = (StringRef("start ") + PSFilename).str();
+
     args.clear();
     args.push_back(ViewerPath.c_str());
     switch (PSViewer) {
@@ -237,6 +256,11 @@
       args.push_back("--spartan");
       args.push_back(PSFilename.c_str());
       break;
+    case PDFV_Start:
+      args.push_back("/S");
+      args.push_back("/C");
+      args.push_back(StartArg.c_str());
+      break;
     case PSV_None:
       llvm_unreachable("Invalid viewer");
     }