diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index ebf071c..3bbe5d4 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -264,13 +264,17 @@
         return;
       IS.OptLevel = NewOptLevel;
       IS.TM.setOptLevel(NewOptLevel);
-      SavedFastISel = IS.TM.Options.EnableFastISel;
-      if (NewOptLevel == CodeGenOpt::None)
-        IS.TM.setFastISel(true);
       DEBUG(dbgs() << "\nChanging optimization level for Function "
             << IS.MF->getFunction()->getName() << "\n");
       DEBUG(dbgs() << "\tBefore: -O" << SavedOptLevel
             << " ; After: -O" << NewOptLevel << "\n");
+      SavedFastISel = IS.TM.Options.EnableFastISel;
+      if (NewOptLevel == CodeGenOpt::None) {
+        IS.TM.setFastISel(IS.TM.getO0WantsFastISel());
+        DEBUG(dbgs() << "\tFastISel is "
+              << (IS.TM.Options.EnableFastISel ? "enabled" : "disabled")
+              << "\n");
+      }
     }
 
     ~OptLevelChanger() {