diff --git a/llvm/lib/CodeGen/MachineCopyPropagation.cpp b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
index d3bdc77..3bf8147 100644
--- a/llvm/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
@@ -517,7 +517,7 @@
       if (MO.isDef() && !MO.isEarlyClobber()) {
         Defs.push_back(Reg);
         continue;
-      } else if (MO.readsReg())
+      } else if (!MO.isDebug() && MO.readsReg())
         ReadRegister(Reg);
     }