Index: include/clang/CodeGen/BackendUtil.h
===================================================================
--- include/clang/CodeGen/BackendUtil.h
+++ include/clang/CodeGen/BackendUtil.h
@@ -37,7 +37,8 @@
   void EmitBackendOutput(DiagnosticsEngine &Diags, const CodeGenOptions &CGOpts,
                          const TargetOptions &TOpts, const LangOptions &LOpts,
                          const llvm::DataLayout &TDesc, llvm::Module *M,
-                         BackendAction Action, raw_pwrite_stream *OS);
+                         BackendAction Action,
+                         std::unique_ptr<raw_pwrite_stream> OS);
 
   void EmbedBitcode(llvm::Module *M, const CodeGenOptions &CGOpts,
                     llvm::MemoryBufferRef Buf);
Index: include/clang/CodeGen/ObjectFilePCHContainerOperations.h
===================================================================
--- include/clang/CodeGen/ObjectFilePCHContainerOperations.h
+++ include/clang/CodeGen/ObjectFilePCHContainerOperations.h
@@ -22,10 +22,12 @@
   /// Return an ASTConsumer that can be chained with a
   /// PCHGenerator that produces a wrapper file format
   /// that also contains full debug info for the module.
-  std::unique_ptr<ASTConsumer> CreatePCHContainerGenerator(
-      CompilerInstance &CI, const std::string &MainFileName,
-      const std::string &OutputFileName, llvm::raw_pwrite_stream *OS,
-      std::shared_ptr<PCHBuffer> Buffer) const override;
+  std::unique_ptr<ASTConsumer>
+  CreatePCHContainerGenerator(CompilerInstance &CI,
+                              const std::string &MainFileName,
+                              const std::string &OutputFileName,
+                              std::unique_ptr<llvm::raw_pwrite_stream> OS,
+                              std::shared_ptr<PCHBuffer> Buffer) const override;
 };
 
 /// A PCHContainerReader implementation that uses LLVM to
Index: include/clang/Frontend/ASTConsumers.h
===================================================================
--- include/clang/Frontend/ASTConsumers.h
+++ include/clang/Frontend/ASTConsumers.h
@@ -31,7 +31,7 @@
 // original C code.  The output is intended to be in a format such that
 // clang could re-parse the output back into the same AST, but the
 // implementation is still incomplete.
-std::unique_ptr<ASTConsumer> CreateASTPrinter(raw_ostream *OS,
+std::unique_ptr<ASTConsumer> CreateASTPrinter(std::unique_ptr<raw_ostream> OS,
                                               StringRef FilterString);
 
 // AST dumper: dumps the raw AST in human-readable form to stderr; this is
Index: include/clang/Frontend/CompilerInstance.h
===================================================================
--- include/clang/Frontend/CompilerInstance.h
+++ include/clang/Frontend/CompilerInstance.h
@@ -155,15 +155,10 @@
   struct OutputFile {
     std::string Filename;
     std::string TempFilename;
-    std::unique_ptr<raw_ostream> OS;
-
-    OutputFile(std::string filename, std::string tempFilename,
-               std::unique_ptr<raw_ostream> OS)
-        : Filename(std::move(filename)), TempFilename(std::move(tempFilename)),
-          OS(std::move(OS)) {}
-    OutputFile(OutputFile &&O)
-        : Filename(std::move(O.Filename)),
-          TempFilename(std::move(O.TempFilename)), OS(std::move(O.OS)) {}
+
+    OutputFile(std::string filename, std::string tempFilename)
+        : Filename(std::move(filename)), TempFilename(std::move(tempFilename)) {
+    }
   };
 
   /// If the output doesn't support seeking (terminal, pipe). we switch
@@ -577,8 +572,8 @@
   /// \param OutFile - The output file info.
   void addOutputFile(OutputFile &&OutFile);
 
-  /// clearOutputFiles - Clear the output file list, destroying the contained
-  /// output streams.
+  /// clearOutputFiles - Clear the output file list. The underlying output
+  /// streams must have been closed beforehand.
   ///
   /// \param EraseFiles - If true, attempt to erase the files from disk.
   void clearOutputFiles(bool EraseFiles);
@@ -685,19 +680,18 @@
   /// atomically replace the target output on success).
   ///
   /// \return - Null on error.
-  raw_pwrite_stream *createDefaultOutputFile(bool Binary = true,
-                                             StringRef BaseInput = "",
-                                             StringRef Extension = "");
+  std::unique_ptr<raw_pwrite_stream>
+  createDefaultOutputFile(bool Binary = true, StringRef BaseInput = "",
+                          StringRef Extension = "");
 
   /// Create a new output file and add it to the list of tracked output files,
   /// optionally deriving the output path name.
   ///
   /// \return - Null on error.
-  raw_pwrite_stream *createOutputFile(StringRef OutputPath, bool Binary,
-                                      bool RemoveFileOnSignal,
-                                      StringRef BaseInput, StringRef Extension,
-                                      bool UseTemporary,
-                                      bool CreateMissingDirectories = false);
+  std::unique_ptr<raw_pwrite_stream>
+  createOutputFile(StringRef OutputPath, bool Binary, bool RemoveFileOnSignal,
+                   StringRef BaseInput, StringRef Extension, bool UseTemporary,
+                   bool CreateMissingDirectories = false);
 
   /// Create a new output file, optionally deriving the output path name.
   ///
@@ -731,7 +725,7 @@
                    bool CreateMissingDirectories, std::string *ResultPathName,
                    std::string *TempPathName);
 
-  llvm::raw_null_ostream *createNullOutputFile();
+  std::unique_ptr<raw_pwrite_stream> createNullOutputFile();
 
   /// }
   /// @name Initialization Utility Methods
Index: include/clang/Frontend/FrontendActions.h
===================================================================
--- include/clang/Frontend/FrontendActions.h
+++ include/clang/Frontend/FrontendActions.h
@@ -85,7 +85,7 @@
   /// create the PCHGenerator instance returned by CreateASTConsumer.
   ///
   /// \returns true if an error occurred, false otherwise.
-  static raw_pwrite_stream *
+  static std::unique_ptr<raw_pwrite_stream>
   ComputeASTConsumerArguments(CompilerInstance &CI, StringRef InFile,
                               std::string &Sysroot, std::string &OutputFile);
 };
@@ -117,10 +117,9 @@
   /// create the PCHGenerator instance returned by CreateASTConsumer.
   ///
   /// \returns true if an error occurred, false otherwise.
-  raw_pwrite_stream *ComputeASTConsumerArguments(CompilerInstance &CI,
-                                                 StringRef InFile,
-                                                 std::string &Sysroot,
-                                                 std::string &OutputFile);
+  std::unique_ptr<raw_pwrite_stream>
+  ComputeASTConsumerArguments(CompilerInstance &CI, StringRef InFile,
+                              std::string &Sysroot, std::string &OutputFile);
 };
 
 class SyntaxOnlyAction : public ASTFrontendAction {
Index: include/clang/Frontend/PCHContainerOperations.h
===================================================================
--- include/clang/Frontend/PCHContainerOperations.h
+++ include/clang/Frontend/PCHContainerOperations.h
@@ -46,10 +46,12 @@
   /// Return an ASTConsumer that can be chained with a
   /// PCHGenerator that produces a wrapper file format containing a
   /// serialized AST bitstream.
-  virtual std::unique_ptr<ASTConsumer> CreatePCHContainerGenerator(
-      CompilerInstance &CI, const std::string &MainFileName,
-      const std::string &OutputFileName, llvm::raw_pwrite_stream *OS,
-      std::shared_ptr<PCHBuffer> Buffer) const = 0;
+  virtual std::unique_ptr<ASTConsumer>
+  CreatePCHContainerGenerator(CompilerInstance &CI,
+                              const std::string &MainFileName,
+                              const std::string &OutputFileName,
+                              std::unique_ptr<llvm::raw_pwrite_stream> OS,
+                              std::shared_ptr<PCHBuffer> Buffer) const = 0;
 };
 
 /// This abstract interface provides operations for unwrapping
@@ -73,10 +75,12 @@
 
   /// Return an ASTConsumer that can be chained with a
   /// PCHGenerator that writes the module to a flat file.
-  std::unique_ptr<ASTConsumer> CreatePCHContainerGenerator(
-      CompilerInstance &CI, const std::string &MainFileName,
-      const std::string &OutputFileName, llvm::raw_pwrite_stream *OS,
-      std::shared_ptr<PCHBuffer> Buffer) const override;
+  std::unique_ptr<ASTConsumer>
+  CreatePCHContainerGenerator(CompilerInstance &CI,
+                              const std::string &MainFileName,
+                              const std::string &OutputFileName,
+                              std::unique_ptr<llvm::raw_pwrite_stream> OS,
+                              std::shared_ptr<PCHBuffer> Buffer) const override;
 };
 
 /// Implements read operations for a raw pass-through PCH container.
Index: include/clang/Rewrite/Frontend/ASTConsumers.h
===================================================================
--- include/clang/Rewrite/Frontend/ASTConsumers.h
+++ include/clang/Rewrite/Frontend/ASTConsumers.h
@@ -28,17 +28,18 @@
 // ObjC rewriter: attempts to rewrite ObjC constructs into pure C code.
 // This is considered experimental, and only works with Apple's ObjC runtime.
 std::unique_ptr<ASTConsumer>
-CreateObjCRewriter(const std::string &InFile, raw_ostream *OS,
+CreateObjCRewriter(const std::string &InFile, std::unique_ptr<raw_ostream> OS,
                    DiagnosticsEngine &Diags, const LangOptions &LOpts,
                    bool SilenceRewriteMacroWarning);
 std::unique_ptr<ASTConsumer>
-CreateModernObjCRewriter(const std::string &InFile, raw_ostream *OS,
+CreateModernObjCRewriter(const std::string &InFile,
+                         std::unique_ptr<raw_ostream> OS,
                          DiagnosticsEngine &Diags, const LangOptions &LOpts,
                          bool SilenceRewriteMacroWarning, bool LineInfo);
 
 /// CreateHTMLPrinter - Create an AST consumer which rewrites source code to
 /// HTML with syntax highlighting suitable for viewing in a web-browser.
-std::unique_ptr<ASTConsumer> CreateHTMLPrinter(raw_ostream *OS,
+std::unique_ptr<ASTConsumer> CreateHTMLPrinter(std::unique_ptr<raw_ostream> OS,
                                                Preprocessor &PP,
                                                bool SyntaxHighlight = true,
                                                bool HighlightMacros = true);
Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -61,6 +61,8 @@
 
   Timer CodeGenerationTime;
 
+  std::unique_ptr<raw_pwrite_stream> OS;
+
   mutable legacy::PassManager *CodeGenPasses;
   mutable legacy::PassManager *PerModulePasses;
   mutable legacy::FunctionPassManager *PerFunctionPasses;
@@ -139,7 +141,8 @@
 
   std::unique_ptr<TargetMachine> TM;
 
-  void EmitAssembly(BackendAction Action, raw_pwrite_stream *OS);
+  void EmitAssembly(BackendAction Action,
+                    std::unique_ptr<raw_pwrite_stream> OS);
 };
 
 // We need this wrapper to access LangOpts and CGOpts from extension functions
@@ -675,7 +678,7 @@
 }
 
 void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
-                                      raw_pwrite_stream *OS) {
+                                      std::unique_ptr<raw_pwrite_stream> OS) {
   TimeRegion Region(llvm::TimePassesIsEnabled ? &CodeGenerationTime : nullptr);
 
   setCommandLineOpts();
@@ -758,6 +761,8 @@
     PrettyStackTraceString CrashInfo("Code generation");
     CodeGenPasses->run(*TheModule);
   }
+
+  this->OS = std::move(OS);
 }
 
 void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
@@ -765,10 +770,10 @@
                               const clang::TargetOptions &TOpts,
                               const LangOptions &LOpts, const llvm::DataLayout &TDesc,
                               Module *M, BackendAction Action,
-                              raw_pwrite_stream *OS) {
+                              std::unique_ptr<raw_pwrite_stream> OS) {
   EmitAssemblyHelper AsmHelper(Diags, CGOpts, TOpts, LOpts, M);
 
-  AsmHelper.EmitAssembly(Action, OS);
+  AsmHelper.EmitAssembly(Action, std::move(OS));
 
   // Verify clang's TargetInfo DataLayout against the LLVM TargetMachine's
   // DataLayout.
Index: lib/CodeGen/CodeGenAction.cpp
===================================================================
--- lib/CodeGen/CodeGenAction.cpp
+++ lib/CodeGen/CodeGenAction.cpp
@@ -46,7 +46,7 @@
     const CodeGenOptions &CodeGenOpts;
     const TargetOptions &TargetOpts;
     const LangOptions &LangOpts;
-    raw_pwrite_stream *AsmOutStream;
+    std::unique_ptr<raw_pwrite_stream> AsmOutStream;
     ASTContext *Context;
 
     Timer LLVMIRGeneration;
@@ -68,11 +68,12 @@
         const TargetOptions &TargetOpts, const LangOptions &LangOpts,
         bool TimePasses, const std::string &InFile,
         const SmallVectorImpl<std::pair<unsigned, llvm::Module *>> &LinkModules,
-        raw_pwrite_stream *OS, LLVMContext &C,
+        std::unique_ptr<raw_pwrite_stream> OS, LLVMContext &C,
         CoverageSourceInfo *CoverageInfo = nullptr)
         : Diags(Diags), Action(Action), CodeGenOpts(CodeGenOpts),
-          TargetOpts(TargetOpts), LangOpts(LangOpts), AsmOutStream(OS),
-          Context(nullptr), LLVMIRGeneration("LLVM IR Generation Time"),
+          TargetOpts(TargetOpts), LangOpts(LangOpts),
+          AsmOutStream(std::move(OS)), Context(nullptr),
+          LLVMIRGeneration("LLVM IR Generation Time"),
           Gen(CreateLLVMCodeGen(Diags, InFile, HeaderSearchOpts, PPOpts,
                                 CodeGenOpts, C, CoverageInfo)) {
       llvm::TimePassesIsEnabled = TimePasses;
@@ -177,7 +178,7 @@
 
       EmitBackendOutput(Diags, CodeGenOpts, TargetOpts, LangOpts,
                         C.getTargetInfo().getDataLayout(),
-                        getModule(), Action, AsmOutStream);
+                        getModule(), Action, std::move(AsmOutStream));
 
       Ctx.setInlineAsmDiagnosticHandler(OldHandler, OldContext);
 
@@ -691,7 +692,7 @@
   return VMContext;
 }
 
-static raw_pwrite_stream *
+static std::unique_ptr<raw_pwrite_stream>
 GetOutputStream(CompilerInstance &CI, StringRef InFile, BackendAction Action) {
   switch (Action) {
   case Backend_EmitAssembly:
@@ -701,7 +702,7 @@
   case Backend_EmitBC:
     return CI.createDefaultOutputFile(true, InFile, "bc");
   case Backend_EmitNothing:
-    return nullptr;
+    return {};
   case Backend_EmitMCNull:
     return CI.createNullOutputFile();
   case Backend_EmitObj:
@@ -714,7 +715,7 @@
 std::unique_ptr<ASTConsumer>
 CodeGenAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
   BackendAction BA = static_cast<BackendAction>(Act);
-  raw_pwrite_stream *OS = GetOutputStream(CI, InFile, BA);
+  std::unique_ptr<raw_pwrite_stream> OS = GetOutputStream(CI, InFile, BA);
   if (BA != Backend_EmitNothing && !OS)
     return nullptr;
 
@@ -754,7 +755,7 @@
       BA, CI.getDiagnostics(), CI.getHeaderSearchOpts(),
       CI.getPreprocessorOpts(), CI.getCodeGenOpts(), CI.getTargetOpts(),
       CI.getLangOpts(), CI.getFrontendOpts().ShowTimers, InFile, LinkModules,
-      OS, *VMContext, CoverageInfo));
+      std::move(OS), *VMContext, CoverageInfo));
   BEConsumer = Result.get();
   return std::move(Result);
 }
@@ -786,7 +787,8 @@
   if (getCurrentFileKind() == IK_LLVM_IR) {
     BackendAction BA = static_cast<BackendAction>(Act);
     CompilerInstance &CI = getCompilerInstance();
-    raw_pwrite_stream *OS = GetOutputStream(CI, getCurrentFile(), BA);
+    std::unique_ptr<raw_pwrite_stream> OS =
+        GetOutputStream(CI, getCurrentFile(), BA);
     if (BA != Backend_EmitNothing && !OS)
       return;
 
@@ -843,7 +845,7 @@
 
     EmitBackendOutput(CI.getDiagnostics(), CI.getCodeGenOpts(), TargetOpts,
                       CI.getLangOpts(), CI.getTarget().getDataLayout(),
-                      TheModule.get(), BA, OS);
+                      TheModule.get(), BA, std::move(OS));
     return;
   }
 
Index: lib/CodeGen/ObjectFilePCHContainerOperations.cpp
===================================================================
--- lib/CodeGen/ObjectFilePCHContainerOperations.cpp
+++ lib/CodeGen/ObjectFilePCHContainerOperations.cpp
@@ -55,7 +55,7 @@
   std::unique_ptr<llvm::LLVMContext> VMContext;
   std::unique_ptr<llvm::Module> M;
   std::unique_ptr<CodeGen::CodeGenModule> Builder;
-  raw_pwrite_stream *OS;
+  std::unique_ptr<raw_pwrite_stream> OS;
   std::shared_ptr<PCHBuffer> Buffer;
 
   /// Visit every type and emit debug info for it.
@@ -138,15 +138,15 @@
 public:
   PCHContainerGenerator(CompilerInstance &CI, const std::string &MainFileName,
                         const std::string &OutputFileName,
-                        raw_pwrite_stream *OS,
+                        std::unique_ptr<raw_pwrite_stream> OS,
                         std::shared_ptr<PCHBuffer> Buffer)
       : Diags(CI.getDiagnostics()), MainFileName(MainFileName),
         OutputFileName(OutputFileName), Ctx(nullptr),
         MMap(CI.getPreprocessor().getHeaderSearchInfo().getModuleMap()),
         HeaderSearchOpts(CI.getHeaderSearchOpts()),
         PreprocessorOpts(CI.getPreprocessorOpts()),
-        TargetOpts(CI.getTargetOpts()), LangOpts(CI.getLangOpts()), OS(OS),
-        Buffer(std::move(Buffer)) {
+        TargetOpts(CI.getTargetOpts()), LangOpts(CI.getLangOpts()),
+        OS(std::move(OS)), Buffer(std::move(Buffer)) {
     // The debug info output isn't affected by CodeModel and
     // ThreadModel, but the backend expects them to be nonempty.
     CodeGenOpts.CodeModel = "default";
@@ -281,20 +281,18 @@
     DEBUG({
       // Print the IR for the PCH container to the debug output.
       llvm::SmallString<0> Buffer;
-      llvm::raw_svector_ostream OS(Buffer);
-      clang::EmitBackendOutput(Diags, CodeGenOpts, TargetOpts, LangOpts,
-                               Ctx.getTargetInfo().getDataLayout(), M.get(),
-                               BackendAction::Backend_EmitLL, &OS);
+      clang::EmitBackendOutput(
+          Diags, CodeGenOpts, TargetOpts, LangOpts,
+          Ctx.getTargetInfo().getDataLayout(), M.get(),
+          BackendAction::Backend_EmitLL,
+          llvm::make_unique<llvm::raw_svector_ostream>(Buffer));
       llvm::dbgs() << Buffer;
     });
 
     // Use the LLVM backend to emit the pch container.
     clang::EmitBackendOutput(Diags, CodeGenOpts, TargetOpts, LangOpts,
                              Ctx.getTargetInfo().getDataLayout(), M.get(),
-                             BackendAction::Backend_EmitObj, OS);
-
-    // Make sure the pch container hits disk.
-    OS->flush();
+                             BackendAction::Backend_EmitObj, std::move(OS));
 
     // Free the memory for the temporary buffer.
     llvm::SmallVector<char, 0> Empty;
@@ -307,10 +305,11 @@
 std::unique_ptr<ASTConsumer>
 ObjectFilePCHContainerWriter::CreatePCHContainerGenerator(
     CompilerInstance &CI, const std::string &MainFileName,
-    const std::string &OutputFileName, llvm::raw_pwrite_stream *OS,
+    const std::string &OutputFileName,
+    std::unique_ptr<llvm::raw_pwrite_stream> OS,
     std::shared_ptr<PCHBuffer> Buffer) const {
-  return llvm::make_unique<PCHContainerGenerator>(CI, MainFileName,
-                                                  OutputFileName, OS, Buffer);
+  return llvm::make_unique<PCHContainerGenerator>(
+      CI, MainFileName, OutputFileName, std::move(OS), Buffer);
 }
 
 void ObjectFilePCHContainerReader::ExtractPCH(
Index: lib/Frontend/ASTConsumers.cpp
===================================================================
--- lib/Frontend/ASTConsumers.cpp
+++ lib/Frontend/ASTConsumers.cpp
@@ -35,9 +35,9 @@
     typedef RecursiveASTVisitor<ASTPrinter> base;
 
   public:
-    ASTPrinter(raw_ostream *Out = nullptr, bool Dump = false,
+    ASTPrinter(std::unique_ptr<raw_ostream> Out = nullptr, bool Dump = false,
                StringRef FilterString = "", bool DumpLookups = false)
-        : Out(Out ? *Out : llvm::outs()), Dump(Dump),
+        : Out(Out ? *Out : llvm::outs()), OwnedOut(std::move(Out)), Dump(Dump),
           FilterString(FilterString), DumpLookups(DumpLookups) {}
 
     void HandleTranslationUnit(ASTContext &Context) override {
@@ -94,6 +94,7 @@
     }
 
     raw_ostream &Out;
+    std::unique_ptr<raw_ostream> OwnedOut;
     bool Dump;
     std::string FilterString;
     bool DumpLookups;
@@ -122,9 +123,11 @@
   };
 } // end anonymous namespace
 
-std::unique_ptr<ASTConsumer> clang::CreateASTPrinter(raw_ostream *Out,
-                                                     StringRef FilterString) {
-  return llvm::make_unique<ASTPrinter>(Out, /*Dump=*/false, FilterString);
+std::unique_ptr<ASTConsumer>
+clang::CreateASTPrinter(std::unique_ptr<raw_ostream> Out,
+                        StringRef FilterString) {
+  return llvm::make_unique<ASTPrinter>(std::move(Out), /*Dump=*/false,
+                                       FilterString);
 }
 
 std::unique_ptr<ASTConsumer> clang::CreateASTDumper(StringRef FilterString,
Index: lib/Frontend/ASTUnit.cpp
===================================================================
--- lib/Frontend/ASTUnit.cpp
+++ lib/Frontend/ASTUnit.cpp
@@ -920,17 +920,17 @@
   unsigned &Hash;
   std::vector<Decl *> TopLevelDecls;
   PrecompilePreambleAction *Action;
-  raw_ostream *Out;
+  std::unique_ptr<raw_ostream> Out;
 
 public:
   PrecompilePreambleConsumer(ASTUnit &Unit, PrecompilePreambleAction *Action,
                              const Preprocessor &PP, StringRef isysroot,
-                             raw_ostream *Out)
+                             std::unique_ptr<raw_ostream> Out)
       : PCHGenerator(PP, "", nullptr, isysroot, std::make_shared<PCHBuffer>(),
                      ArrayRef<llvm::IntrusiveRefCntPtr<ModuleFileExtension>>(),
                      /*AllowASTWithErrors=*/true),
         Unit(Unit), Hash(Unit.getCurrentTopLevelHashValue()), Action(Action),
-        Out(Out) {
+        Out(std::move(Out)) {
     Hash = 0;
   }
 
@@ -982,8 +982,9 @@
                                             StringRef InFile) {
   std::string Sysroot;
   std::string OutputFile;
-  raw_ostream *OS = GeneratePCHAction::ComputeASTConsumerArguments(
-      CI, InFile, Sysroot, OutputFile);
+  std::unique_ptr<raw_ostream> OS =
+      GeneratePCHAction::ComputeASTConsumerArguments(CI, InFile, Sysroot,
+                                                     OutputFile);
   if (!OS)
     return nullptr;
 
@@ -994,7 +995,7 @@
       llvm::make_unique<MacroDefinitionTrackerPPCallbacks>(
                                            Unit.getCurrentTopLevelHashValue()));
   return llvm::make_unique<PrecompilePreambleConsumer>(
-      Unit, this, CI.getPreprocessor(), Sysroot, OS);
+      Unit, this, CI.getPreprocessor(), Sysroot, std::move(OS));
 }
 
 static bool isNonDriverDiag(const StoredDiagnostic &StoredDiag) {
Index: lib/Frontend/CompilerInstance.cpp
===================================================================
--- lib/Frontend/CompilerInstance.cpp
+++ lib/Frontend/CompilerInstance.cpp
@@ -542,15 +542,11 @@
 // Output Files
 
 void CompilerInstance::addOutputFile(OutputFile &&OutFile) {
-  assert(OutFile.OS && "Attempt to add empty stream to output list!");
   OutputFiles.push_back(std::move(OutFile));
 }
 
 void CompilerInstance::clearOutputFiles(bool EraseFiles) {
   for (OutputFile &OF : OutputFiles) {
-    // Manually close the stream before we rename it.
-    OF.OS.reset();
-
     if (!OF.TempFilename.empty()) {
       if (EraseFiles) {
         llvm::sys::fs::remove(OF.TempFilename);
@@ -570,13 +566,12 @@
       }
     } else if (!OF.Filename.empty() && EraseFiles)
       llvm::sys::fs::remove(OF.Filename);
-
   }
   OutputFiles.clear();
   NonSeekStream.reset();
 }
 
-raw_pwrite_stream *
+std::unique_ptr<raw_pwrite_stream>
 CompilerInstance::createDefaultOutputFile(bool Binary, StringRef InFile,
                                           StringRef Extension) {
   return createOutputFile(getFrontendOpts().OutputFile, Binary,
@@ -584,14 +579,11 @@
                           /*UseTemporary=*/true);
 }
 
-llvm::raw_null_ostream *CompilerInstance::createNullOutputFile() {
-  auto OS = llvm::make_unique<llvm::raw_null_ostream>();
-  llvm::raw_null_ostream *Ret = OS.get();
-  addOutputFile(OutputFile("", "", std::move(OS)));
-  return Ret;
+std::unique_ptr<raw_pwrite_stream> CompilerInstance::createNullOutputFile() {
+  return llvm::make_unique<llvm::raw_null_ostream>();
 }
 
-raw_pwrite_stream *
+std::unique_ptr<raw_pwrite_stream>
 CompilerInstance::createOutputFile(StringRef OutputPath, bool Binary,
                                    bool RemoveFileOnSignal, StringRef InFile,
                                    StringRef Extension, bool UseTemporary,
@@ -604,16 +596,15 @@
   if (!OS) {
     getDiagnostics().Report(diag::err_fe_unable_to_open_output) << OutputPath
                                                                 << EC.message();
-    return nullptr;
+    return {};
   }
 
-  raw_pwrite_stream *Ret = OS.get();
   // Add the output file -- but don't try to remove "-", since this means we are
   // using stdin.
-  addOutputFile(OutputFile((OutputPathName != "-") ? OutputPathName : "",
-                           TempPathName, std::move(OS)));
+  addOutputFile(
+      OutputFile((OutputPathName != "-") ? OutputPathName : "", TempPathName));
 
-  return Ret;
+  return OS;
 }
 
 std::unique_ptr<llvm::raw_pwrite_stream> CompilerInstance::createOutputFile(
Index: lib/Frontend/FrontendActions.cpp
===================================================================
--- lib/Frontend/FrontendActions.cpp
+++ lib/Frontend/FrontendActions.cpp
@@ -48,8 +48,9 @@
 
 std::unique_ptr<ASTConsumer>
 ASTPrintAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
-  if (raw_ostream *OS = CI.createDefaultOutputFile(false, InFile))
-    return CreateASTPrinter(OS, CI.getFrontendOpts().ASTDumpFilter);
+  if (std::unique_ptr<raw_ostream> OS =
+          CI.createDefaultOutputFile(false, InFile))
+    return CreateASTPrinter(std::move(OS), CI.getFrontendOpts().ASTDumpFilter);
   return nullptr;
 }
 
@@ -80,7 +81,7 @@
 GeneratePCHAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
   std::string Sysroot;
   std::string OutputFile;
-  raw_pwrite_stream *OS =
+  std::unique_ptr<raw_pwrite_stream> OS =
       ComputeASTConsumerArguments(CI, InFile, Sysroot, OutputFile);
   if (!OS)
     return nullptr;
@@ -94,14 +95,16 @@
                         CI.getPreprocessor(), OutputFile, nullptr, Sysroot,
                         Buffer, CI.getFrontendOpts().ModuleFileExtensions));
   Consumers.push_back(CI.getPCHContainerWriter().CreatePCHContainerGenerator(
-      CI, InFile, OutputFile, OS, Buffer));
+      CI, InFile, OutputFile, std::move(OS), Buffer));
 
   return llvm::make_unique<MultiplexConsumer>(std::move(Consumers));
 }
 
-raw_pwrite_stream *GeneratePCHAction::ComputeASTConsumerArguments(
-    CompilerInstance &CI, StringRef InFile, std::string &Sysroot,
-    std::string &OutputFile) {
+std::unique_ptr<raw_pwrite_stream>
+GeneratePCHAction::ComputeASTConsumerArguments(CompilerInstance &CI,
+                                               StringRef InFile,
+                                               std::string &Sysroot,
+                                               std::string &OutputFile) {
   Sysroot = CI.getHeaderSearchOpts().Sysroot;
   if (CI.getFrontendOpts().RelocatablePCH && Sysroot.empty()) {
     CI.getDiagnostics().Report(diag::err_relocatable_without_isysroot);
@@ -111,7 +114,7 @@
   // We use createOutputFile here because this is exposed via libclang, and we
   // must disable the RemoveFileOnSignal behavior.
   // We use a temporary to avoid race conditions.
-  raw_pwrite_stream *OS =
+  std::unique_ptr<raw_pwrite_stream> OS =
       CI.createOutputFile(CI.getFrontendOpts().OutputFile, /*Binary=*/true,
                           /*RemoveFileOnSignal=*/false, InFile,
                           /*Extension=*/"", /*useTemporary=*/true);
@@ -127,7 +130,7 @@
                                         StringRef InFile) {
   std::string Sysroot;
   std::string OutputFile;
-  raw_pwrite_stream *OS =
+  std::unique_ptr<raw_pwrite_stream> OS =
       ComputeASTConsumerArguments(CI, InFile, Sysroot, OutputFile);
   if (!OS)
     return nullptr;
@@ -142,7 +145,7 @@
                         /*IncludeTimestamps=*/
                           +CI.getFrontendOpts().BuildingImplicitModule));
   Consumers.push_back(CI.getPCHContainerWriter().CreatePCHContainerGenerator(
-      CI, InFile, OutputFile, OS, Buffer));
+      CI, InFile, OutputFile, std::move(OS), Buffer));
   return llvm::make_unique<MultiplexConsumer>(std::move(Consumers));
 }
 
@@ -375,9 +378,11 @@
   return true;
 }
 
-raw_pwrite_stream *GenerateModuleAction::ComputeASTConsumerArguments(
-    CompilerInstance &CI, StringRef InFile, std::string &Sysroot,
-    std::string &OutputFile) {
+std::unique_ptr<raw_pwrite_stream>
+GenerateModuleAction::ComputeASTConsumerArguments(CompilerInstance &CI,
+                                                  StringRef InFile,
+                                                  std::string &Sysroot,
+                                                  std::string &OutputFile) {
   // If no output file was provided, figure out where this module would go
   // in the module cache.
   if (CI.getFrontendOpts().OutputFile.empty()) {
@@ -390,7 +395,7 @@
   // We use createOutputFile here because this is exposed via libclang, and we
   // must disable the RemoveFileOnSignal behavior.
   // We use a temporary to avoid race conditions.
-  raw_pwrite_stream *OS =
+  std::unique_ptr<raw_pwrite_stream> OS =
       CI.createOutputFile(CI.getFrontendOpts().OutputFile, /*Binary=*/true,
                           /*RemoveFileOnSignal=*/false, InFile,
                           /*Extension=*/"", /*useTemporary=*/true,
@@ -644,11 +649,12 @@
 
 void GeneratePTHAction::ExecuteAction() {
   CompilerInstance &CI = getCompilerInstance();
-  raw_pwrite_stream *OS = CI.createDefaultOutputFile(true, getCurrentFile());
+  std::unique_ptr<raw_pwrite_stream> OS =
+      CI.createDefaultOutputFile(true, getCurrentFile());
   if (!OS)
     return;
 
-  CacheTokens(CI.getPreprocessor(), OS);
+  CacheTokens(CI.getPreprocessor(), OS.get());
 }
 
 void PreprocessOnlyAction::ExecuteAction() {
@@ -709,10 +715,11 @@
     }
   }
 
-  raw_ostream *OS = CI.createDefaultOutputFile(BinaryMode, getCurrentFile());
+  std::unique_ptr<raw_ostream> OS =
+      CI.createDefaultOutputFile(BinaryMode, getCurrentFile());
   if (!OS) return;
 
-  DoPrintPreprocessedInput(CI.getPreprocessor(), OS,
+  DoPrintPreprocessedInput(CI.getPreprocessor(), OS.get(),
                            CI.getPreprocessorOutputOpts());
 }
 
Index: lib/Frontend/PCHContainerOperations.cpp
===================================================================
--- lib/Frontend/PCHContainerOperations.cpp
+++ lib/Frontend/PCHContainerOperations.cpp
@@ -28,12 +28,12 @@
 /// \brief A PCHContainerGenerator that writes out the PCH to a flat file.
 class RawPCHContainerGenerator : public ASTConsumer {
   std::shared_ptr<PCHBuffer> Buffer;
-  raw_pwrite_stream *OS;
+  std::unique_ptr<raw_pwrite_stream> OS;
 
 public:
-  RawPCHContainerGenerator(llvm::raw_pwrite_stream *OS,
+  RawPCHContainerGenerator(std::unique_ptr<llvm::raw_pwrite_stream> OS,
                            std::shared_ptr<PCHBuffer> Buffer)
-      : Buffer(std::move(Buffer)), OS(OS) {}
+      : Buffer(std::move(Buffer)), OS(std::move(OS)) {}
 
   ~RawPCHContainerGenerator() override = default;
 
@@ -53,9 +53,9 @@
 
 std::unique_ptr<ASTConsumer> RawPCHContainerWriter::CreatePCHContainerGenerator(
     CompilerInstance &CI, const std::string &MainFileName,
-    const std::string &OutputFileName, llvm::raw_pwrite_stream *OS,
+    const std::string &OutputFileName, std::unique_ptr<llvm::raw_pwrite_stream> OS,
     std::shared_ptr<PCHBuffer> Buffer) const {
-  return llvm::make_unique<RawPCHContainerGenerator>(OS, Buffer);
+  return llvm::make_unique<RawPCHContainerGenerator>(std::move(OS), Buffer);
 }
 
 void RawPCHContainerReader::ExtractPCH(
Index: lib/Frontend/Rewrite/FrontendActions.cpp
===================================================================
--- lib/Frontend/Rewrite/FrontendActions.cpp
+++ lib/Frontend/Rewrite/FrontendActions.cpp
@@ -33,8 +33,9 @@
 
 std::unique_ptr<ASTConsumer>
 HTMLPrintAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
-  if (raw_ostream *OS = CI.createDefaultOutputFile(false, InFile))
-    return CreateHTMLPrinter(OS, CI.getPreprocessor());
+  if (std::unique_ptr<raw_ostream> OS =
+          CI.createDefaultOutputFile(false, InFile))
+    return CreateHTMLPrinter(std::move(OS), CI.getPreprocessor());
   return nullptr;
 }
 
@@ -152,14 +153,15 @@
 
 std::unique_ptr<ASTConsumer>
 RewriteObjCAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
-  if (raw_ostream *OS = CI.createDefaultOutputFile(false, InFile, "cpp")) {
+  if (std::unique_ptr<raw_ostream> OS =
+          CI.createDefaultOutputFile(false, InFile, "cpp")) {
     if (CI.getLangOpts().ObjCRuntime.isNonFragile())
       return CreateModernObjCRewriter(
-          InFile, OS, CI.getDiagnostics(), CI.getLangOpts(),
+          InFile, std::move(OS), CI.getDiagnostics(), CI.getLangOpts(),
           CI.getDiagnosticOpts().NoRewriteMacros,
           (CI.getCodeGenOpts().getDebugInfo() != codegenoptions::NoDebugInfo));
-    return CreateObjCRewriter(InFile, OS,
-                              CI.getDiagnostics(), CI.getLangOpts(),
+    return CreateObjCRewriter(InFile, std::move(OS), CI.getDiagnostics(),
+                              CI.getLangOpts(),
                               CI.getDiagnosticOpts().NoRewriteMacros);
   }
   return nullptr;
@@ -173,25 +175,28 @@
 
 void RewriteMacrosAction::ExecuteAction() {
   CompilerInstance &CI = getCompilerInstance();
-  raw_ostream *OS = CI.createDefaultOutputFile(true, getCurrentFile());
+  std::unique_ptr<raw_ostream> OS =
+      CI.createDefaultOutputFile(true, getCurrentFile());
   if (!OS) return;
 
-  RewriteMacrosInInput(CI.getPreprocessor(), OS);
+  RewriteMacrosInInput(CI.getPreprocessor(), OS.get());
 }
 
 void RewriteTestAction::ExecuteAction() {
   CompilerInstance &CI = getCompilerInstance();
-  raw_ostream *OS = CI.createDefaultOutputFile(false, getCurrentFile());
+  std::unique_ptr<raw_ostream> OS =
+      CI.createDefaultOutputFile(false, getCurrentFile());
   if (!OS) return;
 
-  DoRewriteTest(CI.getPreprocessor(), OS);
+  DoRewriteTest(CI.getPreprocessor(), OS.get());
 }
 
 void RewriteIncludesAction::ExecuteAction() {
   CompilerInstance &CI = getCompilerInstance();
-  raw_ostream *OS = CI.createDefaultOutputFile(true, getCurrentFile());
+  std::unique_ptr<raw_ostream> OS =
+      CI.createDefaultOutputFile(true, getCurrentFile());
   if (!OS) return;
 
-  RewriteIncludesInInput(CI.getPreprocessor(), OS,
+  RewriteIncludesInInput(CI.getPreprocessor(), OS.get(),
                          CI.getPreprocessorOutputOpts());
 }
Index: lib/Frontend/Rewrite/HTMLPrint.cpp
===================================================================
--- lib/Frontend/Rewrite/HTMLPrint.cpp
+++ lib/Frontend/Rewrite/HTMLPrint.cpp
@@ -32,14 +32,14 @@
 namespace {
   class HTMLPrinter : public ASTConsumer {
     Rewriter R;
-    raw_ostream *Out;
+    std::unique_ptr<raw_ostream> Out;
     Preprocessor &PP;
     bool SyntaxHighlight, HighlightMacros;
 
   public:
-    HTMLPrinter(raw_ostream *OS, Preprocessor &pp,
+    HTMLPrinter(std::unique_ptr<raw_ostream> OS, Preprocessor &pp,
                 bool _SyntaxHighlight, bool _HighlightMacros)
-      : Out(OS), PP(pp), SyntaxHighlight(_SyntaxHighlight),
+      : Out(std::move(OS)), PP(pp), SyntaxHighlight(_SyntaxHighlight),
         HighlightMacros(_HighlightMacros) {}
 
     void Initialize(ASTContext &context) override;
@@ -47,11 +47,10 @@
   };
 }
 
-std::unique_ptr<ASTConsumer> clang::CreateHTMLPrinter(raw_ostream *OS,
-                                                      Preprocessor &PP,
-                                                      bool SyntaxHighlight,
-                                                      bool HighlightMacros) {
-  return llvm::make_unique<HTMLPrinter>(OS, PP, SyntaxHighlight,
+std::unique_ptr<ASTConsumer>
+clang::CreateHTMLPrinter(std::unique_ptr<raw_ostream> OS, Preprocessor &PP,
+                         bool SyntaxHighlight, bool HighlightMacros) {
+  return llvm::make_unique<HTMLPrinter>(std::move(OS), PP, SyntaxHighlight,
                                         HighlightMacros);
 }
 
Index: lib/Frontend/Rewrite/RewriteModernObjC.cpp
===================================================================
--- lib/Frontend/Rewrite/RewriteModernObjC.cpp
+++ lib/Frontend/Rewrite/RewriteModernObjC.cpp
@@ -72,7 +72,7 @@
     Stmt *CurrentBody;
     ParentMap *PropParentMap; // created lazily.
     std::string InFileName;
-    raw_ostream* OutFile;
+    std::unique_ptr<raw_ostream> OutFile;
     std::string Preamble;
     
     TypeDecl *ProtocolTypeDecl;
@@ -239,9 +239,9 @@
     
     void HandleTopLevelSingleDecl(Decl *D);
     void HandleDeclInMainFile(Decl *D);
-    RewriteModernObjC(std::string inFile, raw_ostream *OS,
-                DiagnosticsEngine &D, const LangOptions &LOpts,
-                bool silenceMacroWarn, bool LineInfo);
+    RewriteModernObjC(std::string inFile, std::unique_ptr<raw_ostream> OS,
+                      DiagnosticsEngine &D, const LangOptions &LOpts,
+                      bool silenceMacroWarn, bool LineInfo);
 
     ~RewriteModernObjC() override {}
 
@@ -643,12 +643,13 @@
   return Ext == "h" || Ext == "hh" || Ext == "H";
 }
 
-RewriteModernObjC::RewriteModernObjC(std::string inFile, raw_ostream* OS,
-                         DiagnosticsEngine &D, const LangOptions &LOpts,
-                         bool silenceMacroWarn,
-                         bool LineInfo)
-      : Diags(D), LangOpts(LOpts), InFileName(inFile), OutFile(OS),
-        SilenceRewriteMacroWarning(silenceMacroWarn), GenerateLineInfo(LineInfo) {
+RewriteModernObjC::RewriteModernObjC(std::string inFile,
+                                     std::unique_ptr<raw_ostream> OS,
+                                     DiagnosticsEngine &D,
+                                     const LangOptions &LOpts,
+                                     bool silenceMacroWarn, bool LineInfo)
+    : Diags(D), LangOpts(LOpts), InFileName(inFile), OutFile(std::move(OS)),
+      SilenceRewriteMacroWarning(silenceMacroWarn), GenerateLineInfo(LineInfo) {
   IsHeader = IsHeaderFile(inFile);
   RewriteFailedDiag = Diags.getCustomDiagID(DiagnosticsEngine::Warning,
                "rewriting sub-expression within a macro (may not be correct)");
@@ -664,10 +665,12 @@
 }
 
 std::unique_ptr<ASTConsumer> clang::CreateModernObjCRewriter(
-    const std::string &InFile, raw_ostream *OS, DiagnosticsEngine &Diags,
-    const LangOptions &LOpts, bool SilenceRewriteMacroWarning, bool LineInfo) {
-  return llvm::make_unique<RewriteModernObjC>(
-      InFile, OS, Diags, LOpts, SilenceRewriteMacroWarning, LineInfo);
+    const std::string &InFile, std::unique_ptr<raw_ostream> OS,
+    DiagnosticsEngine &Diags, const LangOptions &LOpts,
+    bool SilenceRewriteMacroWarning, bool LineInfo) {
+  return llvm::make_unique<RewriteModernObjC>(InFile, std::move(OS), Diags,
+                                              LOpts, SilenceRewriteMacroWarning,
+                                              LineInfo);
 }
 
 void RewriteModernObjC::InitializeCommon(ASTContext &context) {
Index: lib/Frontend/Rewrite/RewriteObjC.cpp
===================================================================
--- lib/Frontend/Rewrite/RewriteObjC.cpp
+++ lib/Frontend/Rewrite/RewriteObjC.cpp
@@ -71,7 +71,7 @@
     Stmt *CurrentBody;
     ParentMap *PropParentMap; // created lazily.
     std::string InFileName;
-    raw_ostream* OutFile;
+    std::unique_ptr<raw_ostream> OutFile;
     std::string Preamble;
     
     TypeDecl *ProtocolTypeDecl;
@@ -190,7 +190,7 @@
 
     void HandleTopLevelSingleDecl(Decl *D);
     void HandleDeclInMainFile(Decl *D);
-    RewriteObjC(std::string inFile, raw_ostream *OS,
+    RewriteObjC(std::string inFile, std::unique_ptr<raw_ostream> OS,
                 DiagnosticsEngine &D, const LangOptions &LOpts,
                 bool silenceMacroWarn);
 
@@ -506,11 +506,10 @@
   
   class RewriteObjCFragileABI : public RewriteObjC {
   public:
-    RewriteObjCFragileABI(std::string inFile, raw_ostream *OS,
-                DiagnosticsEngine &D, const LangOptions &LOpts,
-                bool silenceMacroWarn) : RewriteObjC(inFile, OS,
-                                                     D, LOpts,
-                                                     silenceMacroWarn) {}
+    RewriteObjCFragileABI(std::string inFile, std::unique_ptr<raw_ostream> OS,
+                          DiagnosticsEngine &D, const LangOptions &LOpts,
+                          bool silenceMacroWarn)
+        : RewriteObjC(inFile, std::move(OS), D, LOpts, silenceMacroWarn) {}
 
     ~RewriteObjCFragileABI() override {}
     void Initialize(ASTContext &context) override;
@@ -575,11 +574,11 @@
   return Ext == "h" || Ext == "hh" || Ext == "H";
 }
 
-RewriteObjC::RewriteObjC(std::string inFile, raw_ostream* OS,
+RewriteObjC::RewriteObjC(std::string inFile, std::unique_ptr<raw_ostream> OS,
                          DiagnosticsEngine &D, const LangOptions &LOpts,
                          bool silenceMacroWarn)
-      : Diags(D), LangOpts(LOpts), InFileName(inFile), OutFile(OS),
-        SilenceRewriteMacroWarning(silenceMacroWarn) {
+    : Diags(D), LangOpts(LOpts), InFileName(inFile), OutFile(std::move(OS)),
+      SilenceRewriteMacroWarning(silenceMacroWarn) {
   IsHeader = IsHeaderFile(inFile);
   RewriteFailedDiag = Diags.getCustomDiagID(DiagnosticsEngine::Warning,
                "rewriting sub-expression within a macro (may not be correct)");
@@ -590,11 +589,12 @@
 }
 
 std::unique_ptr<ASTConsumer>
-clang::CreateObjCRewriter(const std::string &InFile, raw_ostream *OS,
+clang::CreateObjCRewriter(const std::string &InFile,
+                          std::unique_ptr<raw_ostream> OS,
                           DiagnosticsEngine &Diags, const LangOptions &LOpts,
                           bool SilenceRewriteMacroWarning) {
-  return llvm::make_unique<RewriteObjCFragileABI>(InFile, OS, Diags, LOpts,
-                                                  SilenceRewriteMacroWarning);
+  return llvm::make_unique<RewriteObjCFragileABI>(
+      InFile, std::move(OS), Diags, LOpts, SilenceRewriteMacroWarning);
 }
 
 void RewriteObjC::InitializeCommon(ASTContext &context) {
Index: tools/clang-check/ClangCheck.cpp
===================================================================
--- tools/clang-check/ClangCheck.cpp
+++ tools/clang-check/ClangCheck.cpp
@@ -142,7 +142,7 @@
       return clang::CreateASTDumper(ASTDumpFilter, /*DumpDecls=*/true,
                                     /*DumpLookups=*/false);
     if (ASTPrint)
-      return clang::CreateASTPrinter(&llvm::outs(), ASTDumpFilter);
+      return clang::CreateASTPrinter(nullptr, ASTDumpFilter);
     return llvm::make_unique<clang::ASTConsumer>();
   }
 };