Index: llvm/include/llvm/CodeGen/TargetLowering.h
===================================================================
--- llvm/include/llvm/CodeGen/TargetLowering.h
+++ llvm/include/llvm/CodeGen/TargetLowering.h
@@ -231,6 +231,11 @@
   TargetLoweringBase &operator=(const TargetLoweringBase &) = delete;
   virtual ~TargetLoweringBase() = default;
 
+  /// Return true if the target support strict float operation
+  bool isStrictFPEnabled() const {
+    return IsStrictFPEnabled;
+  }
+
 protected:
   /// Initialize all of the actions to default values.
   void initActions();
@@ -2932,6 +2937,8 @@
   /// details.
   MachineBasicBlock *emitXRayTypedEvent(MachineInstr &MI,
                                         MachineBasicBlock *MBB) const;
+
+  bool IsStrictFPEnabled;
 };
 
 /// This class defines information used to lower LLVM code to legal SelectionDAG
Index: llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -52,6 +52,7 @@
 #include <utility>
 
 using namespace llvm;
+extern cl::opt<bool> DisableStrictNodeMutation;
 
 #define DEBUG_TYPE "legalizedag"
 
@@ -3711,7 +3712,8 @@
     break;
   }
 
-  if (Results.empty() && Node->isStrictFPOpcode()) {
+  if ((!DisableStrictNodeMutation && !TLI.isStrictFPEnabled())
+      && Results.empty() && Node->isStrictFPOpcode()) {
     // FIXME: We were asked to expand a strict floating-point operation,
     // but there is currently no expansion implemented that would preserve
     // the "strict" properties.  For now, we just fall back to the non-strict
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -135,6 +135,14 @@
         cl::desc("use Machine Branch Probability Info"),
         cl::init(true), cl::Hidden);
 
+// FIXME: This option is only to test if the strict fp operation processed
+// correctly by preventing mutating strict fp operation to normal fp operation
+// during development. When the backend supports strict float operation, this
+// option will be meaningless.
+cl::opt<bool> DisableStrictNodeMutation("disable-strictnode-mutation",
+       cl::desc("Don't mutate strict-float node to a legalize node"),
+       cl::init(false), cl::Hidden);
+
 #ifndef NDEBUG
 static cl::opt<std::string>
 FilterDAGBasicBlockName("filter-view-dags", cl::Hidden,
@@ -1159,8 +1167,9 @@
       // we convert them to normal FP opcodes instead at this point.  This
       // will allow them to be handled by existing target-specific instruction
       // selectors.
-      if (Node->isStrictFPOpcode() &&
-          (TLI->getOperationAction(Node->getOpcode(), Node->getValueType(0))
+      if ((!DisableStrictNodeMutation && !TLI->isStrictFPEnabled())
+          && Node->isStrictFPOpcode()
+          && (TLI->getOperationAction(Node->getOpcode(), Node->getValueType(0))
            != TargetLowering::Legal))
         Node = CurDAG->mutateStrictFPToFP(Node);
 
Index: llvm/lib/CodeGen/TargetLoweringBase.cpp
===================================================================
--- llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -585,6 +585,7 @@
   BooleanVectorContents = UndefinedBooleanContent;
   SchedPreferenceInfo = Sched::ILP;
   GatherAllAliasesMaxDepth = 18;
+  IsStrictFPEnabled = false;
   // TODO: the default will be switched to 0 in the next commit, along
   // with the Target-specific changes necessary.
   MaxAtomicSizeInBitsSupported = 1024;
Index: llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
===================================================================
--- llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
+++ llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
@@ -634,6 +634,9 @@
   // than "STC;MVC".  Handle the choice in target-specific code instead.
   MaxStoresPerMemset = 0;
   MaxStoresPerMemsetOptSize = 0;
+
+  // Default to having -disable-strictnode-mutation on
+   IsStrictFPEnabled = true;
 }
 
 EVT SystemZTargetLowering::getSetCCResultType(const DataLayout &DL,