diff --git a/include/llvm/Support/FileUtilities.h b/include/llvm/Support/FileUtilities.h
index 7e5d40500d6..86d82a14fd9 100644
--- a/include/llvm/Support/FileUtilities.h
+++ b/include/llvm/Support/FileUtilities.h
@@ -28,6 +28,19 @@ namespace llvm {
 bool DiffFiles(const std::string &FileA, const std::string &FileB,
                std::string *Error = 0);
 
+/// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
+/// files match, 1 if they are different, and 2 if there is a file error.  This
+/// function differs from DiffFiles in that you can specify an absolete and
+/// relative FP error that is allowed to exist.  If you specify a string to fill
+/// in for the error option, it will set the string to an error message if an
+/// error occurs, allowing the caller to distinguish between a failed diff and a
+/// file system error.
+///
+int DiffFilesWithTolerance(const std::string &FileA, const std::string &FileB,
+                           double AbsTol, double RelTol,
+                           std::string *Error = 0);
+
+
 /// MoveFileOverIfUpdated - If the file specified by New is different than Old,
 /// or if Old does not exist, move the New file over the Old file.  Otherwise,
 /// remove the New file.