Index: clang/lib/ExtractAPI/ExtractAPIConsumer.cpp
===================================================================
--- clang/lib/ExtractAPI/ExtractAPIConsumer.cpp
+++ clang/lib/ExtractAPI/ExtractAPIConsumer.cpp
@@ -793,7 +793,7 @@
   // FIXME: Make the kind of APISerializer configurable.
   SymbolGraphSerializer SGSerializer(*API, ProductName);
   SGSerializer.serialize(*OS);
-  OS->flush();
+  OS = nullptr;
 }
 
 std::unique_ptr<raw_pwrite_stream>
Index: clang/lib/Frontend/PrecompiledPreamble.cpp
===================================================================
--- clang/lib/Frontend/PrecompiledPreamble.cpp
+++ clang/lib/Frontend/PrecompiledPreamble.cpp
@@ -248,7 +248,7 @@
     if (FileOS) {
       *FileOS << Buffer->Data;
       // Make sure it hits disk now.
-      FileOS->flush();
+      FileOS = nullptr;
     }
 
     this->HasEmittedPreamblePCH = true;
Index: clang/tools/driver/cc1_main.cpp
===================================================================
--- clang/tools/driver/cc1_main.cpp
+++ clang/tools/driver/cc1_main.cpp
@@ -260,8 +260,7 @@
             Path.str(), /*Binary=*/false, /*RemoveFileOnSignal=*/false,
             /*useTemporary=*/false)) {
       llvm::timeTraceProfilerWrite(*profilerOutput);
-      // FIXME(ibiryukov): make profilerOutput flush in destructor instead.
-      profilerOutput->flush();
+      profilerOutput = nullptr;
       llvm::timeTraceProfilerCleanup();
       Clang->clearOutputFiles(false);
     }