diff --git a/llvm/include/llvm/CodeGen/SelectionDAGTargetInfo.h b/llvm/include/llvm/CodeGen/SelectionDAGTargetInfo.h
--- a/llvm/include/llvm/CodeGen/SelectionDAGTargetInfo.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAGTargetInfo.h
@@ -160,6 +160,11 @@
   virtual bool generateFMAsInMachineCombiner(CodeGenOpt::Level OptLevel) const {
     return false;
   }
+
+  // Return true if the Machine Combiner should disable generic combines.
+  virtual bool disableGenericCombines(CodeGenOpt::Level OptLevel) const {
+    return false;
+  }
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -130,6 +130,7 @@
   class DAGCombiner {
     SelectionDAG &DAG;
     const TargetLowering &TLI;
+    const SelectionDAGTargetInfo *STI;
     CombineLevel Level;
     CodeGenOpt::Level OptLevel;
     bool LegalDAG = false;
@@ -223,8 +224,9 @@
 
   public:
     DAGCombiner(SelectionDAG &D, AliasAnalysis *AA, CodeGenOpt::Level OL)
-        : DAG(D), TLI(D.getTargetLoweringInfo()), Level(BeforeLegalizeTypes),
-          OptLevel(OL), AA(AA) {
+        : DAG(D), TLI(D.getTargetLoweringInfo()),
+          STI(D.getSubtarget().getSelectionDAGInfo()),
+          Level(BeforeLegalizeTypes), OptLevel(OL), AA(AA) {
       ForCodeSize = DAG.shouldOptForSize();
 
       MaximumLegalStoreInBits = 0;
@@ -1649,7 +1651,9 @@
 }
 
 SDValue DAGCombiner::combine(SDNode *N) {
-  SDValue RV = visit(N);
+  SDValue RV;
+  if (!STI || !STI->disableGenericCombines(OptLevel))
+    RV = visit(N);
 
   // If nothing happened, try a target-specific DAG combine.
   if (!RV.getNode()) {
@@ -11747,7 +11751,6 @@
   if (!AllowFusionGlobally && !isContractable(N))
     return SDValue();
 
-  const SelectionDAGTargetInfo *STI = DAG.getSubtarget().getSelectionDAGInfo();
   if (STI && STI->generateFMAsInMachineCombiner(OptLevel))
     return SDValue();
 
@@ -11965,7 +11968,6 @@
   if (!AllowFusionGlobally && !isContractable(N))
     return SDValue();
 
-  const SelectionDAGTargetInfo *STI = DAG.getSubtarget().getSelectionDAGInfo();
   if (STI && STI->generateFMAsInMachineCombiner(OptLevel))
     return SDValue();