Index: include/clang/Basic/DiagnosticFrontendKinds.td
===================================================================
--- include/clang/Basic/DiagnosticFrontendKinds.td
+++ include/clang/Basic/DiagnosticFrontendKinds.td
@@ -37,6 +37,8 @@
 def note_fe_backend_optimization_remark_missing_loc : Note<"use "
   "-gline-tables-only -gcolumn-info to track source location information "
   "for this optimization remark">;
+def note_fe_backend_optimization_remark_invalid_loc : Note<"could "
+  "not determine the original source location for %0:%1:%2">;
 
 def err_fe_invalid_code_complete_file : Error<
     "cannot locate code-completion file %0">, DefaultFatal;
Index: lib/CodeGen/CodeGenAction.cpp
===================================================================
--- lib/CodeGen/CodeGenAction.cpp
+++ lib/CodeGen/CodeGenAction.cpp
@@ -396,13 +396,13 @@
     unsigned Line, Column;
     D.getLocation(&Filename, &Line, &Column);
     SourceLocation Loc;
-    if (Line > 0) {
+    const FileEntry *FE = FileMgr.getFile(Filename);
+    if (FE && Line > 0) {
       // If -gcolumn-info was not used, Column will be 0. This upsets the
       // source manager, so if Column is not set, set it to 1.
       if (Column == 0)
         Column = 1;
-      Loc = SourceMgr.translateFileLineCol(FileMgr.getFile(Filename), Line,
-                                           Column);
+      Loc = SourceMgr.translateFileLineCol(FE, Line, Column);
     }
     Diags.Report(Loc, diag::remark_fe_backend_optimization_remark)
         << AddFlagValue(D.getPassName()) << D.getMsg().str();
@@ -415,6 +415,13 @@
       // -Rpass is used. !srcloc annotations need to be emitted in
       // approximately the same spots as !dbg nodes.
       Diags.Report(diag::note_fe_backend_optimization_remark_missing_loc);
+    else if (Loc.isInvalid())
+      // If we were not able to translate the file:line:col information
+      // back to a SourceLocation, at least emit a note stating that
+      // we could not translate this location. This can happen in the
+      // case of #line directives.
+      Diags.Report(diag::note_fe_backend_optimization_remark_invalid_loc)
+        << Filename << Line << Column;
   }
 }
 
Index: test/Frontend/optimization-remark-line-directive.c
===================================================================
--- /dev/null
+++ test/Frontend/optimization-remark-line-directive.c
@@ -0,0 +1,15 @@
+// This file tests -Rpass diagnostics together with #line
+// directives. We cannot map #line directives back to
+// a SourceLocation.
+
+// RUN: %clang -c %s -Rpass=inline -O0 -S -gmlt -o /dev/null 2> %t.err
+// RUN: FileCheck < %t.err %s --check-prefix=INLINE-INVALID-LOC
+//
+int foo(int x, int y) __attribute__((always_inline));
+int foo(int x, int y) { return x + y; }
+
+#line 1230 "/bad/path/to/original.c"
+int bar(int j) { return foo(j, j - 2); }
+
+// INLINE-INVALID-LOC: {{^remark: foo inlined into bar}}
+// INLINE-INVALID-LOC: note: could not determine the source location for /bad/path/to/original.c:1230:0