diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index f7b4c09162a..8cdb94c152a 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2081,6 +2081,11 @@ void DwarfDebug::collectVariableInfo() {
       // FIXME : Lift this restriction.
       if (MInsn->getNumOperands() != 3)
         continue;
+
+      // Ignore Undef values.
+      if (!MInsn->getOperand(0).getReg())
+        continue;
+
       DIVariable DV(
         const_cast<MDNode *>(MInsn->getOperand(MInsn->getNumOperands() - 1)
                                .getMetadata()));
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 9d239c1bd7c..d663521abaf 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3834,15 +3834,10 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
         return 0;
       DAG.AddDbgValue(SDV, N.getNode(), isParameter);
     } else {
-      // Generating Undefs here seems to be actively harmful because it
-      // affects the line numbers.
-      return 0;
-#if 0
       // This isn't useful, but it shows what we're missing.
       SDV = DAG.getDbgValue(Variable, UndefValue::get(Address->getType()),
                             0, dl, SDNodeOrder);
       DAG.AddDbgValue(SDV, 0, isParameter);
-#endif
     }
     return 0;
   }