Index: include/clang/Driver/CC1Options.td
===================================================================
--- include/clang/Driver/CC1Options.td
+++ include/clang/Driver/CC1Options.td
@@ -636,6 +636,8 @@
 
 }
 
+def echo_main_file_name : Flag<["-"], "echo-main-file-name">,
+  HelpText<"Echo the main file name">;
 def fblocks_runtime_optional : Flag<["-"], "fblocks-runtime-optional">,
   HelpText<"Weakly link in the blocks runtime">;
 def fexternc_nounwind : Flag<["-"], "fexternc-nounwind">,
Index: include/clang/Driver/CLCompatOptions.td
===================================================================
--- include/clang/Driver/CLCompatOptions.td
+++ include/clang/Driver/CLCompatOptions.td
@@ -158,6 +158,9 @@
 def _SLASH_showIncludes : CLFlag<"showIncludes">,
   HelpText<"Print info about included files to stderr">,
   Alias<show_includes>;
+def _SLASH_showFilenames : CLFlag<"showFilenames">,
+  HelpText<"Print the name of each compiled file">,
+  Alias<echo_main_file_name>;
 def _SLASH_source_charset : CLCompileJoined<"source-charset:">,
   HelpText<"Source encoding, supports only UTF-8">, Alias<finput_charset_EQ>;
 def _SLASH_execution_charset : CLCompileJoined<"execution-charset:">,
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -3530,6 +3530,8 @@
   // -save-temps.
   CmdArgs.push_back("-main-file-name");
   CmdArgs.push_back(getBaseInputName(Args, Input));
+  if (Arg *A = Args.getLastArg(options::OPT_echo_main_file_name))
+    A->render(Args, CmdArgs);
 
   // Some flags which affect the language (via preprocessor
   // defines).
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -789,6 +789,9 @@
   Opts.PreferVectorWidth = Args.getLastArgValue(OPT_mprefer_vector_width_EQ);
 
   Opts.MainFileName = Args.getLastArgValue(OPT_main_file_name);
+  if (Args.hasArg(OPT_echo_main_file_name))
+    llvm::outs() << Opts.MainFileName << "\n";
+
   Opts.VerifyModule = !Args.hasArg(OPT_disable_llvm_verifier);
 
   Opts.ControlFlowGuard = Args.hasArg(OPT_cfguard);
Index: test/CodeGen/echo-main-filename.c
===================================================================
--- /dev/null
+++ test/CodeGen/echo-main-filename.c
@@ -0,0 +1,3 @@
+// RUN: %clang_cc1 -main-file-name foobar -echo-main-file-name %s -emit-llvm -o - | FileCheck %s
+
+// CHECK: foobar
Index: test/Driver/cl-options.c
===================================================================
--- test/Driver/cl-options.c
+++ test/Driver/cl-options.c
@@ -294,6 +294,9 @@
 // RUN: %clang_cl /d1PP -### -- %s 2>&1 | FileCheck -check-prefix=d1PP %s
 // d1PP: -dD
 
+// RUN: %clang_cl /showFilenames -### -- %s 2>&1 | FileCheck -check-prefix=showFilenames %s
+// showFilenames: -echo-main-file-name
+
 // We forward any unrecognized -W diagnostic options to cc1.
 // RUN: %clang_cl -Wunused-pragmas -### -- %s 2>&1 | FileCheck -check-prefix=WJoined %s
 // WJoined: "-cc1"