Index: clang/lib/Basic/SourceManager.cpp
===================================================================
--- clang/lib/Basic/SourceManager.cpp
+++ clang/lib/Basic/SourceManager.cpp
@@ -1251,22 +1251,16 @@
   const unsigned char *Buf = (const unsigned char *)Buffer->getBufferStart();
   const unsigned char *End = (const unsigned char *)Buffer->getBufferEnd();
   unsigned I = 0;
-  while (true) {
-    // Skip over the contents of the line.
-    while (Buf[I] != '\n' && Buf[I] != '\r' && Buf[I] != '\0')
-      ++I;
-
-    if (Buf[I] == '\n' || Buf[I] == '\r') {
+  while (Buf + I < End) {
+    if (Buf[I] == '\n') {
+      LineOffsets.push_back(I + 1);
+    } else if (Buf[I] == '\r') {
       // If this is \r\n, skip both characters.
-      if (Buf[I] == '\r' && Buf[I+1] == '\n')
+      if (Buf + I + 1 < End && Buf[I + 1] == '\n')
         ++I;
-      ++I;
-      LineOffsets.push_back(I);
-    } else {
-      // Otherwise, this is a NUL. If end of file, exit.
-      if (Buf+I == End) break;
-      ++I;
+      LineOffsets.push_back(I + 1);
     }
+    ++I;
   }
 
   // Copy the offsets into the FileInfo structure.