diff --git a/lib/Basic/SourceManager.cpp b/lib/Basic/SourceManager.cpp
index 27cb9be..27a859c 100644
--- a/lib/Basic/SourceManager.cpp
+++ b/lib/Basic/SourceManager.cpp
@@ -98,11 +98,17 @@
           << Entry->getName() << ErrorStr;
 
       Buffer.setInt(true);
-    } else if (FileInfo.st_size != Entry->getSize() ||
-               FileInfo.st_mtime != Entry->getModificationTime()) {
-      // Check that the file's size, modification time, and inode are
-      // the same as in the file entry (which may have come from a
-      // stat cache).
+    } else if (FileInfo.st_size != Entry->getSize()
+#if !defined(LLVM_ON_WIN32)
+               // In our regression testing, the Windows file system
+               // seems to have inconsistent modification times that
+               // sometimes erroneously trigger this error-handling
+               // path.
+               || FileInfo.st_mtime != Entry->getModificationTime()
+#endif
+               ) {
+      // Check that the file's size and modification time are the same
+      // as in the file entry (which may have come from a stat cache).
       if (Diag.isDiagnosticInFlight())
         Diag.SetDelayedDiagnostic(diag::err_file_modified, 
                                   Entry->getName());