Index: tools/dsymutil/DwarfLinker.cpp
===================================================================
--- a/llvm/tools/dsymutil/DwarfLinker.cpp	(revision 313871)
+++ b/llvm/tools/dsymutil/DwarfLinker.cpp	(revision 313872)
@@ -1496,7 +1496,11 @@
 
   if ((RefCU = getUnitForOffset(Units, RefOffset)))
-    if (const auto RefDie = RefCU->getOrigUnit().getDIEForOffset(RefOffset))
-      return RefDie;
+    if (const auto RefDie = RefCU->getOrigUnit().getDIEForOffset(RefOffset)) {
+      // In a file with broken references, an attribute might point to a NULL
+      // DIE.
+      if(!RefDie.isNULL())
+        return RefDie;
+    }
 
   Linker.reportWarning("could not find referenced DIE", &DIE);
   return DWARFDie();