diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
--- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
+++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -1136,6 +1136,8 @@
             LLVM_DEBUG(dbgs() << "Skipping due to debug counter\n");
             continue;
           }
+	  //Salvage debug info early to be compatible with removeRedundantDbgInstrsUsingBackwardScan().
+          salvageDebugInfoOrMarkUndef(Inst);
           if (!Inst.use_empty())
             Inst.replaceAllUsesWith(Op);
           salvageKnowledge(&Inst, &AC);