Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -1246,6 +1246,9 @@
   Flag <["-"], "fno-implicit-modules">,
   Group<f_Group>, Flags<[DriverOption, CC1Option]>;
 def fretain_comments_from_system_headers : Flag<["-"], "fretain-comments-from-system-headers">, Group<f_Group>, Flags<[CC1Option]>;
+def ffile_macro_prefix_to_remove : Joined<["-"], "ffile-macro-prefix-to-remove=">,
+  Group<f_Group>, Flags<[DriverOption, CC1Option]>,
+  HelpText<"prefix to be removed from expanded string of __FILE__ macro">;
 
 def fmudflapth : Flag<["-"], "fmudflapth">, Group<f_Group>;
 def fmudflap : Flag<["-"], "fmudflap">, Group<f_Group>;
Index: include/clang/Lex/PreprocessorOptions.h
===================================================================
--- include/clang/Lex/PreprocessorOptions.h
+++ include/clang/Lex/PreprocessorOptions.h
@@ -127,12 +127,16 @@
   /// manipulation of the compiler invocation object, in cases where the 
   /// compiler invocation and its buffers will be reused.
   bool RetainRemappedFileBuffers = false;
-  
+
   /// \brief The Objective-C++ ARC standard library that we should support,
   /// by providing appropriate definitions to retrofit the standard library
   /// with support for lifetime-qualified pointers.
   ObjCXXARCStandardLibraryKind ObjCXXARCStandardLibrary = ARCXX_nolib;
-    
+
+  /// \brief This string will be used in expanding __FILE__ macro. If it
+  /// matches the prefix of __FILE__, the matched part won't be expanded.
+  std::string FileMacroPrefixToRemove;
+
   /// \brief Records the set of modules
   class FailedModulesSet {
     llvm::StringSet<> Failed;
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -1264,6 +1264,15 @@
     // For IAMCU add special include arguments.
     getToolChain().AddIAMCUIncludeArgs(Args, CmdArgs);
   }
+
+  // Add FILE macro prefix removing arguments or basename only flags.
+  if (const Arg *A =
+          Args.getLastArg(options::OPT_ffile_macro_prefix_to_remove)) {
+    StringRef PrefixToRemove(A->getValue());
+    if (!PrefixToRemove.empty())
+      CmdArgs.push_back(Args.MakeArgString("-ffile-macro-prefix-to-remove=" +
+                                           PrefixToRemove));
+  }
 }
 
 // FIXME: Move to target hook.
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -2826,6 +2826,10 @@
       Opts.ObjCXXARCStandardLibrary = (ObjCXXARCStandardLibraryKind)Library;
   }
 
+  if (Arg *A = Args.getLastArg(OPT_ffile_macro_prefix_to_remove)) {
+    Opts.FileMacroPrefixToRemove = A->getValue();
+  }
+
   // Always avoid lexing editor placeholders when we're just running the
   // preprocessor as we never want to emit the
   // "editor placeholder in source file" error in PP only mode.
Index: lib/Lex/PPMacroExpansion.cpp
===================================================================
--- lib/Lex/PPMacroExpansion.cpp
+++ lib/Lex/PPMacroExpansion.cpp
@@ -26,9 +26,10 @@
 #include "clang/Lex/LexDiagnostic.h"
 #include "clang/Lex/MacroArgs.h"
 #include "clang/Lex/MacroInfo.h"
+#include "clang/Lex/PTHLexer.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/PreprocessorLexer.h"
-#include "clang/Lex/PTHLexer.h"
+#include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Lex/Token.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
@@ -36,15 +37,16 @@
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
@@ -1717,7 +1719,16 @@
     // Escape this filename.  Turn '\' -> '\\' '"' -> '\"'
     SmallString<128> FN;
     if (PLoc.isValid()) {
-      FN += PLoc.getFilename();
+      StringRef Filename = PLoc.getFilename();
+      if (II == Ident__FILE__) {
+        const std::string &PrefixToRemove =
+            getPreprocessorOpts().FileMacroPrefixToRemove;
+        if (Filename.startswith(PrefixToRemove))
+          FN += Filename.substr(PrefixToRemove.size());
+        else
+          FN += Filename;
+      } else
+        FN += Filename;
       Lexer::Stringify(FN);
       OS << '"' << FN << '"';
     }