diff --git a/lldb/include/lldb/Utility/FileSpec.h b/lldb/include/lldb/Utility/FileSpec.h
--- a/lldb/include/lldb/Utility/FileSpec.h
+++ b/lldb/include/lldb/Utility/FileSpec.h
@@ -329,8 +329,8 @@
   /// filename has no extension, ConstString(nullptr) is returned. The dot
   /// ('.') character is the first character in the returned string.
   ///
-  /// \return Returns the extension of the file as a ConstString object.
-  ConstString GetFileNameExtension() const;
+  /// \return Returns the extension of the file as a StringRef.
+  llvm::StringRef GetFileNameExtension() const;
 
   /// Return the filename without the extension part
   ///
diff --git a/lldb/source/Commands/CommandObjectTarget.cpp b/lldb/source/Commands/CommandObjectTarget.cpp
--- a/lldb/source/Commands/CommandObjectTarget.cpp
+++ b/lldb/source/Commands/CommandObjectTarget.cpp
@@ -2163,7 +2163,7 @@
     const char *pcm_path = command.GetArgumentAtIndex(0);
     FileSpec pcm_file{pcm_path};
 
-    if (pcm_file.GetFileNameExtension().GetStringRef() != ".pcm") {
+    if (pcm_file.GetFileNameExtension() != ".pcm") {
       result.AppendError("file must have a .pcm extension");
       return false;
     }
diff --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
--- a/lldb/source/Core/Debugger.cpp
+++ b/lldb/source/Core/Debugger.cpp
@@ -607,8 +607,8 @@
                    llvm::StringRef path) {
   Status error;
 
-  static ConstString g_dylibext(".dylib");
-  static ConstString g_solibext(".so");
+  static constexpr llvm::StringLiteral g_dylibext(".dylib");
+  static constexpr llvm::StringLiteral g_solibext(".so");
 
   if (!baton)
     return FileSystem::eEnumerateDirectoryResultQuit;
diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
--- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -2029,7 +2029,7 @@
   // contain the note section specifying the environment to Android but the
   // custom extension and file name makes it highly unlikely that this will
   // collide with anything else.
-  ConstString file_extension = m_file.GetFileNameExtension();
+  llvm::StringRef file_extension = m_file.GetFileNameExtension();
   bool skip_oatdata_oatexec =
       file_extension == ".oat" || file_extension == ".odex";
 
diff --git a/lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp b/lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp
--- a/lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp
+++ b/lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp
@@ -281,7 +281,7 @@
 Status PlatformAndroid::DownloadSymbolFile(const lldb::ModuleSP &module_sp,
                                            const FileSpec &dst_file_spec) {
   // For oat file we can try to fetch additional debug info from the device
-  ConstString extension = module_sp->GetFileSpec().GetFileNameExtension();
+  llvm::StringRef extension = module_sp->GetFileSpec().GetFileNameExtension();
   if (extension != ".oat" && extension != ".odex")
     return Status(
         "Symbol file downloading only supported for oat and odex files");
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp
@@ -418,8 +418,8 @@
 FileSystem::EnumerateDirectoryResult
 PlatformDarwinKernel::FindKDKandSDKDirectoriesInDirectory(
     void *baton, llvm::sys::fs::file_type ft, llvm::StringRef path) {
-  static ConstString g_sdk_suffix = ConstString(".sdk");
-  static ConstString g_kdk_suffix = ConstString(".kdk");
+  static constexpr llvm::StringLiteral g_sdk_suffix = ".sdk";
+  static constexpr llvm::StringLiteral g_kdk_suffix = ".kdk";
 
   PlatformDarwinKernel *thisp = (PlatformDarwinKernel *)baton;
   FileSpec file_spec(path);
@@ -480,11 +480,11 @@
 PlatformDarwinKernel::GetKernelsAndKextsInDirectoryHelper(
     void *baton, llvm::sys::fs::file_type ft, llvm::StringRef path,
     bool recurse) {
-  static ConstString g_kext_suffix = ConstString(".kext");
-  static ConstString g_dsym_suffix = ConstString(".dSYM");
+  static constexpr llvm::StringLiteral g_kext_suffix = ".kext";
+  static constexpr llvm::StringLiteral g_dsym_suffix = ".dSYM";
 
   FileSpec file_spec(path);
-  ConstString file_spec_extension = file_spec.GetFileNameExtension();
+  llvm::StringRef file_spec_extension = file_spec.GetFileNameExtension();
 
   Log *log = GetLog(LLDBLog::Platform);
 
@@ -664,7 +664,7 @@
 //    /dir/dir/mach.development.t7004
 bool PlatformDarwinKernel::KerneldSYMHasNoSiblingBinary(
     const FileSpec &kernel_dsym) {
-  static ConstString g_dsym_suffix = ConstString(".dSYM");
+  static constexpr llvm::StringLiteral g_dsym_suffix = ".dSYM";
   std::string possible_path = kernel_dsym.GetPath();
   if (kernel_dsym.GetFileNameExtension() != g_dsym_suffix)
     return false;
@@ -694,7 +694,7 @@
 std::vector<FileSpec>
 PlatformDarwinKernel::GetDWARFBinaryInDSYMBundle(FileSpec dsym_bundle) {
   std::vector<FileSpec> results;
-  static ConstString g_dsym_suffix = ConstString(".dSYM");
+  static constexpr llvm::StringLiteral g_dsym_suffix = ".dSYM";
   if (dsym_bundle.GetFileNameExtension() != g_dsym_suffix) {
     return results;
   }
diff --git a/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp b/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
--- a/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
@@ -137,7 +137,7 @@
                                                llvm::inconvertibleErrorCode());
   }
 
-  ConstString module_extension = file.GetFileNameExtension();
+  llvm::StringRef module_extension = file.GetFileNameExtension();
   if (module_extension != ".lua") {
     return llvm::make_error<llvm::StringError>("invalid extension",
                                                llvm::inconvertibleErrorCode());
diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
--- a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
@@ -306,7 +306,7 @@
   // On windows, we need to manually back out of the python tree, and go into
   // the bin directory. This is pretty much the inverse of what ComputePythonDir
   // does.
-  if (this_file.GetFileNameExtension() == ConstString(".pyd")) {
+  if (this_file.GetFileNameExtension() == ".pyd") {
     this_file.RemoveLastPathComponent(); // _lldb.pyd or _lldb_d.pyd
     this_file.RemoveLastPathComponent(); // lldb
     llvm::StringRef libdir = LLDB_PYTHON_RELATIVE_LIBDIR;
diff --git a/lldb/source/Utility/FileSpec.cpp b/lldb/source/Utility/FileSpec.cpp
--- a/lldb/source/Utility/FileSpec.cpp
+++ b/lldb/source/Utility/FileSpec.cpp
@@ -399,9 +399,8 @@
     Denormalize(path, m_style);
 }
 
-ConstString FileSpec::GetFileNameExtension() const {
-  return ConstString(
-      llvm::sys::path::extension(m_filename.GetStringRef(), m_style));
+llvm::StringRef FileSpec::GetFileNameExtension() const {
+  return llvm::sys::path::extension(m_filename.GetStringRef(), m_style);
 }
 
 ConstString FileSpec::GetFileNameStrippingExtension() const {
@@ -478,8 +477,8 @@
 ///     \b true if the filespec represents an implementation source
 ///     file, \b false otherwise.
 bool FileSpec::IsSourceImplementationFile() const {
-  ConstString extension(GetFileNameExtension());
-  if (!extension)
+  llvm::StringRef extension = GetFileNameExtension();
+  if (extension.empty())
     return false;
 
   static RegularExpression g_source_file_regex(llvm::StringRef(
@@ -487,7 +486,7 @@
       "cC][pP]|[sS]|[aA][sS][mM]|[fF]|[fF]77|[fF]90|[fF]95|[fF]03|[fF][oO]["
       "rR]|[fF][tT][nN]|[fF][pP][pP]|[aA][dD][aA]|[aA][dD][bB]|[aA][dD][sS])"
       "$"));
-  return g_source_file_regex.Execute(extension.GetStringRef());
+  return g_source_file_regex.Execute(extension);
 }
 
 bool FileSpec::IsRelative() const {
diff --git a/lldb/unittests/Utility/FileSpecTest.cpp b/lldb/unittests/Utility/FileSpecTest.cpp
--- a/lldb/unittests/Utility/FileSpecTest.cpp
+++ b/lldb/unittests/Utility/FileSpecTest.cpp
@@ -456,7 +456,7 @@
   FileSpec just_dot = PosixSpec("/tmp/bar.");
 
   EXPECT_TRUE(dylib.GetFileNameExtension() == ".dylib");
-  EXPECT_TRUE(exe.GetFileNameExtension() == ConstString(nullptr));
+  EXPECT_TRUE(exe.GetFileNameExtension() == llvm::StringRef());
   EXPECT_TRUE(dSYM.GetFileNameExtension() == ".dSYM");
   EXPECT_TRUE(just_dot.GetFileNameExtension() == ".");
 
@@ -464,7 +464,7 @@
   FileSpec win_noext = WindowsSpec("C:\\tmp\\foo");
 
   EXPECT_TRUE(dll.GetFileNameExtension() == ".dll");
-  EXPECT_TRUE(win_noext.GetFileNameExtension() == ConstString(nullptr));
+  EXPECT_TRUE(win_noext.GetFileNameExtension() == llvm::StringRef());
 }
 
 TEST(FileSpecTest, TestFileNameStrippingExtension) {