diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 6df5521b25cc0..c258870072613 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -543,7 +543,7 @@ std::string CompilerInstance::getSpecificModuleCachePath(StringRef ModuleHash) {
   SmallString<256> SpecificModuleCache(getHeaderSearchOpts().ModuleCachePath);
   if (!SpecificModuleCache.empty() && !getHeaderSearchOpts().DisableModuleHash)
     llvm::sys::path::append(SpecificModuleCache, ModuleHash);
-  return std::string(SpecificModuleCache.str());
+  return std::string(SpecificModuleCache);
 }
 
 // ASTContext
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index b5e192d54465b..ed9cd1299eae2 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3176,7 +3176,7 @@ static bool ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
       llvm::sys::fs::make_absolute(WorkingDir, P);
   }
   llvm::sys::path::remove_dots(P);
-  Opts.ModuleCachePath = std::string(P.str());
+  Opts.ModuleCachePath = std::string(P);
 
   // Only the -fmodule-file=<name>=<file> form.
   for (const auto *A : Args.filtered(OPT_fmodule_file)) {
@@ -3217,7 +3217,7 @@ static bool ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
       SmallString<32> Buffer;
       llvm::sys::path::append(Buffer, Opts.Sysroot,
                               llvm::StringRef(A->getValue()).substr(1));
-      Path = std::string(Buffer.str());
+      Path = std::string(Buffer);
     }
 
     Opts.AddPath(Path, Group, IsFramework,
diff --git a/clang/lib/Frontend/LogDiagnosticPrinter.cpp b/clang/lib/Frontend/LogDiagnosticPrinter.cpp
index 32fc6cb2acd87..469d1c22633aa 100644
--- a/clang/lib/Frontend/LogDiagnosticPrinter.cpp
+++ b/clang/lib/Frontend/LogDiagnosticPrinter.cpp
@@ -134,7 +134,7 @@ void LogDiagnosticPrinter::HandleDiagnostic(DiagnosticsEngine::Level Level,
   // Format the message.
   SmallString<100> MessageStr;
   Info.FormatDiagnostic(MessageStr);
-  DE.Message = std::string(MessageStr.str());
+  DE.Message = std::string(MessageStr);
 
   // Set the location information.
   DE.Filename = "";
diff --git a/clang/lib/Frontend/Rewrite/FrontendActions.cpp b/clang/lib/Frontend/Rewrite/FrontendActions.cpp
index 92921bf6f3d7b..cf5a9437e89e6 100644
--- a/clang/lib/Frontend/Rewrite/FrontendActions.cpp
+++ b/clang/lib/Frontend/Rewrite/FrontendActions.cpp
@@ -88,7 +88,7 @@ class FixItRewriteToTemp : public FixItOptions {
     llvm::sys::fs::createTemporaryFile(llvm::sys::path::filename(Filename),
                                        llvm::sys::path::extension(Filename).drop_front(), fd,
                                        Path);
-    return std::string(Path.str());
+    return std::string(Path);
   }
 };
 } // end anonymous namespace
diff --git a/clang/lib/Frontend/TextDiagnosticBuffer.cpp b/clang/lib/Frontend/TextDiagnosticBuffer.cpp
index 90f273e65f88f..681bc25f46b83 100644
--- a/clang/lib/Frontend/TextDiagnosticBuffer.cpp
+++ b/clang/lib/Frontend/TextDiagnosticBuffer.cpp
@@ -32,20 +32,20 @@ void TextDiagnosticBuffer::HandleDiagnostic(DiagnosticsEngine::Level Level,
                          "Diagnostic not handled during diagnostic buffering!");
   case DiagnosticsEngine::Note:
     All.emplace_back(Level, Notes.size());
-    Notes.emplace_back(Info.getLocation(), std::string(Buf.str()));
+    Notes.emplace_back(Info.getLocation(), std::string(Buf));
     break;
   case DiagnosticsEngine::Warning:
     All.emplace_back(Level, Warnings.size());
-    Warnings.emplace_back(Info.getLocation(), std::string(Buf.str()));
+    Warnings.emplace_back(Info.getLocation(), std::string(Buf));
     break;
   case DiagnosticsEngine::Remark:
     All.emplace_back(Level, Remarks.size());
-    Remarks.emplace_back(Info.getLocation(), std::string(Buf.str()));
+    Remarks.emplace_back(Info.getLocation(), std::string(Buf));
     break;
   case DiagnosticsEngine::Error:
   case DiagnosticsEngine::Fatal:
     All.emplace_back(Level, Errors.size());
-    Errors.emplace_back(Info.getLocation(), std::string(Buf.str()));
+    Errors.emplace_back(Info.getLocation(), std::string(Buf));
     break;
   }
 }