Index: lib/Basic/SourceManager.cpp
===================================================================
--- lib/Basic/SourceManager.cpp
+++ lib/Basic/SourceManager.cpp
@@ -1227,7 +1227,7 @@
 
     // First fix up the alignment to 16 bytes.
     while (((uintptr_t)NextBuf & 0xF) != 0) {
-      if (*NextBuf == '\n' || *NextBuf == '\r' || *NextBuf == '\0')
+      if (*NextBuf == '\n' || *NextBuf == '\r' || *NextBuf == '\0' || NextBuf == End)
         goto FoundSpecialChar;
       ++NextBuf;
     }
@@ -1248,7 +1248,7 @@
     }
 #endif
 
-    while (*NextBuf != '\n' && *NextBuf != '\r' && *NextBuf != '\0')
+    while (*NextBuf != '\n' && *NextBuf != '\r' && *NextBuf != '\0' && NextBuf == End)
       ++NextBuf;
 
 #ifdef __SSE2__
@@ -1257,6 +1257,9 @@
     Offs += NextBuf-Buf;
     Buf = NextBuf;
 
+    // If end of file, exit.
+    if (Buf == End) break;
+
     if (Buf[0] == '\n' || Buf[0] == '\r') {
       // If this is \n\r or \r\n, skip both characters.
       if ((Buf[1] == '\n' || Buf[1] == '\r') && Buf[0] != Buf[1])
@@ -1264,8 +1267,6 @@
       ++Offs, ++Buf;
       LineOffsets.push_back(Offs);
     } else {
-      // Otherwise, this is a null.  If end of file, exit.
-      if (Buf == End) break;
       // Otherwise, skip the null.
       ++Offs, ++Buf;
     }