Index: lib/CodeGen/PeepholeOptimizer.cpp
===================================================================
--- lib/CodeGen/PeepholeOptimizer.cpp
+++ lib/CodeGen/PeepholeOptimizer.cpp
@@ -1889,8 +1889,10 @@
   assert(Def && "This method needs a valid definition");
 
   assert(
-      (DefIdx < Def->getDesc().getNumDefs() || Def->getDesc().isVariadic()) &&
-      Def->getOperand(DefIdx).isDef() && "Invalid DefIdx");
+      (Def->getOperand(DefIdx).isDef() &&
+       (DefIdx < Def->getDesc().getNumDefs() || Def->getDesc().isVariadic()) ||
+       Def->getOperand(DefIdx).isImplicit()) &&
+       "Invalid DefIdx");
   if (Def->isCopy())
     return getNextSourceFromCopy();
   if (Def->isBitcast())