Index: lib/Frontend/PrintPreprocessedOutput.cpp
===================================================================
--- lib/Frontend/PrintPreprocessedOutput.cpp
+++ lib/Frontend/PrintPreprocessedOutput.cpp
@@ -562,8 +562,13 @@
   const char *Prefix;
   PrintPPOutputPPCallbacks *Callbacks;
 
-  UnknownPragmaHandler(const char *prefix, PrintPPOutputPPCallbacks *callbacks)
-    : Prefix(prefix), Callbacks(callbacks) {}
+  // Set to true if tokens should be expanded
+  unsigned ShouldExpandTokens : 1;
+
+  UnknownPragmaHandler(const char *prefix, PrintPPOutputPPCallbacks *callbacks,
+                       bool RequireTokenExpansion)
+      : Prefix(prefix), Callbacks(callbacks),
+        ShouldExpandTokens(RequireTokenExpansion) {}
   void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
                     Token &PragmaTok) override {
     // Figure out what line we went to and insert the appropriate number of
@@ -571,16 +576,24 @@
     Callbacks->startNewLineIfNeeded();
     Callbacks->MoveToLine(PragmaTok.getLocation());
     Callbacks->OS.write(Prefix, strlen(Prefix));
+
+    Token PrevToken;
+    Token PrevPrevToken;
+    PrevToken.startToken();
+    PrevPrevToken.startToken();
+
     // Read and print all of the pragma tokens.
     while (PragmaTok.isNot(tok::eod)) {
-      if (PragmaTok.hasLeadingSpace())
+      if (PragmaTok.hasLeadingSpace() ||
+          Callbacks->AvoidConcat(PrevPrevToken, PrevToken, PragmaTok))
         Callbacks->OS << ' ';
       std::string TokSpell = PP.getSpelling(PragmaTok);
       Callbacks->OS.write(&TokSpell[0], TokSpell.size());
 
-      // Expand macros in pragmas with -fms-extensions.  The assumption is that
-      // the majority of pragmas in such a file will be Microsoft pragmas.
-      if (PP.getLangOpts().MicrosoftExt)
+      PrevPrevToken = PrevToken;
+      PrevToken = PragmaTok;
+
+      if (ShouldExpandTokens)
         PP.Lex(PragmaTok);
       else
         PP.LexUnexpandedToken(PragmaTok);
@@ -718,10 +731,29 @@
 
   PrintPPOutputPPCallbacks *Callbacks = new PrintPPOutputPPCallbacks(
       PP, *OS, !Opts.ShowLineMarkers, Opts.ShowMacros, Opts.UseLineDirectives);
-  PP.AddPragmaHandler(new UnknownPragmaHandler("#pragma", Callbacks));
-  PP.AddPragmaHandler("GCC", new UnknownPragmaHandler("#pragma GCC",Callbacks));
-  PP.AddPragmaHandler("clang",
-                      new UnknownPragmaHandler("#pragma clang", Callbacks));
+
+  // Expand macros in pragmas with -fms-extensions.  The assumption is that
+  // the majority of pragmas in such a file will be Microsoft pragmas.
+  PP.AddPragmaHandler(new UnknownPragmaHandler(
+      "#pragma", Callbacks,
+      /*RequireTokenExpansion=*/PP.getLangOpts().MicrosoftExt));
+  PP.AddPragmaHandler(
+      "GCC", new UnknownPragmaHandler(
+                 "#pragma GCC", Callbacks,
+                 /*RequireTokenExpansion=*/PP.getLangOpts().MicrosoftExt));
+  PP.AddPragmaHandler(
+      "clang", new UnknownPragmaHandler(
+                   "#pragma clang", Callbacks,
+                   /*RequireTokenExpansion=*/PP.getLangOpts().MicrosoftExt));
+
+  // The tokens after pragma omp need to be expanded.
+  //
+  //  OpenMP [2.1, Directive format]
+  //  Preprocessing tokens following the #pragma omp are subject to macro
+  //  replacement.
+  PP.AddPragmaHandler("omp",
+                      new UnknownPragmaHandler("#pragma omp", Callbacks,
+                                               /*RequireTokenExpansion=*/true));
 
   PP.addPPCallbacks(std::unique_ptr<PPCallbacks>(Callbacks));
 
Index: test/Preprocessor/openmp-macro-expansion.c
===================================================================
--- /dev/null
+++ test/Preprocessor/openmp-macro-expansion.c
@@ -0,0 +1,31 @@
+// RUN:   %clang_cc1 -fopenmp -E -o - %s 2>&1 | FileCheck %s
+
+// This is to make sure the pragma name is not expanded!
+#define omp (0xDEADBEEF)
+
+#define N 2
+#define M 1
+#define E N>
+
+#define map_to_be_expanded(x) map(tofrom:x)
+#define sched_to_be_expanded(x,s) schedule(x,s)
+#define reda_to_be_expanded(x) reduction(+:x)
+#define redb_to_be_expanded(x,op) reduction(op:x)
+
+void foo(int *a, int *b) {
+  //CHECK: omp target map(a[0:2]) map(tofrom:b[0:2*1])
+  #pragma omp target map(a[0:N]) map_to_be_expanded(b[0:2*M])
+  {
+    int reda;
+    int redb;
+    //CHECK: omp parallel for schedule(static,2> >1) reduction(+:reda) reduction(*:redb)
+    #pragma omp parallel for sched_to_be_expanded(static, E>1) \
+        reda_to_be_expanded(reda) redb_to_be_expanded(redb,*)
+    for (int i = 0; i < N; ++i) {
+      reda += a[i];
+      redb += b[i];
+    }
+    a[0] = reda;
+    b[0] = redb;
+  }
+}