3 files changed, 33 insertions, 10 deletions

diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 84d837d4883..9a4bcc2722e 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -1641,6 +1641,14 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
   } else if (ModuleName == getLangOpts().CurrentModule) {
     // This is the module we're building. 
     Module = PP->getHeaderSearchInfo().lookupModule(ModuleName);
+    /// FIXME: perhaps we should (a) look for a module using the module name
+    //  to file map (PrebuiltModuleFiles) and (b) diagnose if still not found?
+    //if (Module == nullptr) {
+    //  getDiagnostics().Report(ModuleNameLoc, diag::err_module_not_found)
+    //    << ModuleName;
+    //  ModuleBuildFailed = true;
+    //  return ModuleLoadResult();
+    //}
     Known = KnownModules.insert(std::make_pair(Path[0].first, Module)).first;
   } else {
     // Search for a module with the given name.
@@ -1662,16 +1670,17 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
     }
 
     // Try to load the module from the prebuilt module path.
-    if (Source == ModuleNotFound && !HSOpts.PrebuiltModulePaths.empty()) {
-      ModuleFileName = PP->getHeaderSearchInfo().getModuleFileName(
-          ModuleName, "", /*UsePrebuiltPath*/ true);
+    if (Source == ModuleNotFound && (!HSOpts.PrebuiltModuleFiles.empty() ||
+                                     !HSOpts.PrebuiltModulePaths.empty())) {
+      ModuleFileName =
+        PP->getHeaderSearchInfo().getPrebuiltModuleFileName(ModuleName);
       if (!ModuleFileName.empty())
         Source = PrebuiltModulePath;
     }
 
     // Try to load the module from the module cache.
     if (Source == ModuleNotFound && Module) {
-      ModuleFileName = PP->getHeaderSearchInfo().getModuleFileName(Module);
+      ModuleFileName = PP->getHeaderSearchInfo().getCachedModuleFileName(Module);
       Source = ModuleCache;
     }
 
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 2cc93c1f13d..f9dafbb88ea 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1009,9 +1009,12 @@ static void ParseDependencyOutputArgs(DependencyOutputOptions &Opts,
   // They won't be discovered by the regular preprocessor, so
   // we let make / ninja to know about this implicit dependency.
   Opts.ExtraDeps = Args.getAllArgValues(OPT_fdepfile_entry);
-  auto ModuleFiles = Args.getAllArgValues(OPT_fmodule_file);
-  Opts.ExtraDeps.insert(Opts.ExtraDeps.end(), ModuleFiles.begin(),
-                        ModuleFiles.end());
+  // Only the -fmodule-file=<file> form.
+  for (const Arg *A : Args.filtered(OPT_fmodule_file)) {
+    StringRef Val = A->getValue();
+    if (Val.find('=') == StringRef::npos)
+      Opts.ExtraDeps.push_back(Val);
+  }
 }
 
 static bool parseShowColorsArgs(const ArgList &Args, bool DefaultColor) {
@@ -1340,7 +1343,12 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   Opts.UseGlobalModuleIndex = !Args.hasArg(OPT_fno_modules_global_index);
   Opts.GenerateGlobalModuleIndex = Opts.UseGlobalModuleIndex;
   Opts.ModuleMapFiles = Args.getAllArgValues(OPT_fmodule_map_file);
-  Opts.ModuleFiles = Args.getAllArgValues(OPT_fmodule_file);
+  // Only the -fmodule-file=<file> form.
+  for (const Arg *A : Args.filtered(OPT_fmodule_file)) {
+    StringRef Val = A->getValue();
+    if (Val.find('=') == StringRef::npos)
+      Opts.ModuleFiles.push_back(Val);
+  }
   Opts.ModulesEmbedFiles = Args.getAllArgValues(OPT_fmodules_embed_file_EQ);
   Opts.ModulesEmbedAllFiles = Args.hasArg(OPT_fmodules_embed_all_files);
   Opts.IncludeTimestamps = !Args.hasArg(OPT_fno_pch_timestamp);
@@ -1544,6 +1552,12 @@ static void ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
   Opts.ModuleCachePath = P.str();
 
   Opts.ModuleUserBuildPath = Args.getLastArgValue(OPT_fmodules_user_build_path);
+  // Only the -fmodule-file=<name>=<file> form.
+  for (const Arg *A : Args.filtered(OPT_fmodule_file)) {
+    StringRef Val = A->getValue();
+    if (Val.find('=') != StringRef::npos)
+      Opts.PrebuiltModuleFiles.insert(Val.split('='));
+  }
   for (const Arg *A : Args.filtered(OPT_fprebuilt_module_path))
     Opts.AddPrebuiltModulePath(A->getValue());
   Opts.DisableModuleHash = Args.hasArg(OPT_fdisable_module_hash);
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
index d42400183a4..3e3483d2c6b 100644
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -185,8 +185,8 @@ GenerateModuleFromModuleMapAction::CreateOutputFile(CompilerInstance &CI,
 
     HeaderSearch &HS = CI.getPreprocessor().getHeaderSearchInfo();
     CI.getFrontendOpts().OutputFile =
-        HS.getModuleFileName(CI.getLangOpts().CurrentModule, ModuleMapFile,
-                             /*UsePrebuiltPath=*/false);
+        HS.getCachedModuleFileName(CI.getLangOpts().CurrentModule,
+                                   ModuleMapFile);
   }
 
   // We use createOutputFile here because this is exposed via libclang, and we