diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index 6ac3f3fafc89..fa911feed26b 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -513,10 +513,13 @@ Lexer::ComputePreamble(const llvm::MemoryBuffer *Buffer,
   // "fake" file source location at offset 1 so that the lexer will track our
   // position within the file.
   const unsigned StartOffset = 1;
-  SourceLocation StartLoc = SourceLocation::getFromRawEncoding(StartOffset);
-  Lexer TheLexer(StartLoc, LangOpts, Buffer->getBufferStart(),
+  SourceLocation FileLoc = SourceLocation::getFromRawEncoding(StartOffset);
+  Lexer TheLexer(FileLoc, LangOpts, Buffer->getBufferStart(),
                  Buffer->getBufferStart(), Buffer->getBufferEnd());
-  
+
+  // StartLoc will differ from FileLoc if there is a BOM that was skipped.
+  SourceLocation StartLoc = TheLexer.getSourceLocation();
+
   bool InPreprocessorDirective = false;
   Token TheTok;
   Token IfStartTok;
diff --git a/clang/test/Index/preamble-reparse-with-BOM.m b/clang/test/Index/preamble-reparse-with-BOM.m
new file mode 100644
index 000000000000..a2a89c8d8e15
--- /dev/null
+++ b/clang/test/Index/preamble-reparse-with-BOM.m
@@ -0,0 +1,6 @@
+
+@interface I2
+@end
+
+// RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_FAILONERROR=1 \
+// RUN:   c-index-test -test-load-source-reparse 1 local %s