Index: lib/Lex/PPDirectives.cpp
===================================================================
--- lib/Lex/PPDirectives.cpp
+++ lib/Lex/PPDirectives.cpp
@@ -1887,8 +1887,8 @@
 
       // Check for likely typos due to leading or trailing non-isAlphanumeric
       // characters
+      StringRef OriginalFilename = Filename;
       if (!File) {
-        StringRef OriginalFilename = Filename;
         while (!isAlphanumeric(Filename.front())) {
           Filename = Filename.drop_front();
         }
@@ -1915,7 +1915,7 @@
 
       // If the file is still not found, just go with the vanilla diagnostic
       if (!File)
-        Diag(FilenameTok, diag::err_pp_file_not_found) << Filename
+        Diag(FilenameTok, diag::err_pp_file_not_found) << OriginalFilename
                                                        << FilenameRange;
     }
   }
Index: test/Preprocessor/include-leading-nonalpha-no-suggest.c
===================================================================
--- /dev/null
+++ test/Preprocessor/include-leading-nonalpha-no-suggest.c
@@ -0,0 +1,3 @@
+// RUN: %clang_cc1 %s -verify
+
+#include "/non_existing_file_to_include.h" // expected-error {{'/non_existing_file_to_include.h' file not found}}
Index: test/Preprocessor/include-leading-nonalpha-suggest.c
===================================================================
--- /dev/null
+++ test/Preprocessor/include-leading-nonalpha-suggest.c
@@ -0,0 +1,3 @@
+// RUN: %clang_cc1 %s -verify
+
+#include "/empty_file_to_include.h" // expected-error {{'/empty_file_to_include.h' file not found, did you mean 'empty_file_to_include.h'?}}