Index: lib/IR/DIBuilder.cpp
===================================================================
--- lib/IR/DIBuilder.cpp
+++ lib/IR/DIBuilder.cpp
@@ -894,6 +894,8 @@
   DIDescriptor Context(getNonCompileUnitScope(Scope));
   assert((!Context || Context.isScope()) &&
          "createLocalVariable should be called with a valid Context");
+  assert(((LineNo & (0xFF << 24)) == 0) &&
+         "LineNo exceeds maximum line number");
   Value *Elts[] = {HeaderBuilder::get(Tag)
                        .concat(Name)
                        .concat(LineNo | (ArgNo << 24))