diff --git a/clang/lib/Serialization/GeneratePCH.cpp b/clang/lib/Serialization/GeneratePCH.cpp
--- a/clang/lib/Serialization/GeneratePCH.cpp
+++ b/clang/lib/Serialization/GeneratePCH.cpp
@@ -85,6 +85,21 @@
     assert(Module && !Module->IsFromModuleFile &&
            "trying to re-write a module?");
 
+    // Here we would ideally use a P1184 server to find the module name.
+    // However, in the short-term we are going to (ab-)use the name/file pairs
+    // that can be specified with -fmodule-file=Name=Path.  If there is no
+    // entry there, then we fall back to the default CMI name, based on the
+    // source file name.
+    HeaderSearch &HS = PP.getHeaderSearchInfo();
+    const HeaderSearchOptions &HSOpts = HS.getHeaderSearchOpts();
+    std::string ModuleFilename;
+    if (!HSOpts.PrebuiltModuleFiles.empty() ||
+        !HSOpts.PrebuiltModulePaths.empty())
+      ModuleFilename = HS.getPrebuiltModuleFileName(Module->Name);
+
+    if (!ModuleFilename.empty())
+      OutputFile = ModuleFilename;
+
     // So now attach that name to the buffer we are about to create.
     Buffer->PresumedFileName = OutputFile;
   }
diff --git a/clang/lib/Serialization/PCHContainerOperations.cpp b/clang/lib/Serialization/PCHContainerOperations.cpp
--- a/clang/lib/Serialization/PCHContainerOperations.cpp
+++ b/clang/lib/Serialization/PCHContainerOperations.cpp
@@ -77,6 +77,7 @@
           OS.reset(new llvm::raw_fd_ostream(FD, /*shouldClose=*/true));
           *OS << Buffer->Data;
           OS->flush(); // Make sure it hits disk now.
+          // Here we would notify P1184 servers that the module is created
         } else
           llvm::dbgs() << " Problem creating : " << Buffer->PresumedFileName
                        << "\n";