Index: lib/Target/Mips/Mips16ISelDAGToDAG.h
===================================================================
--- lib/Target/Mips/Mips16ISelDAGToDAG.h
+++ lib/Target/Mips/Mips16ISelDAGToDAG.h
@@ -20,7 +20,8 @@
 
 class Mips16DAGToDAGISel : public MipsDAGToDAGISel {
 public:
-  explicit Mips16DAGToDAGISel(MipsTargetMachine &TM) : MipsDAGToDAGISel(TM) {}
+  explicit Mips16DAGToDAGISel(MipsTargetMachine &TM, CodeGenOpt::Level OL)
+      : MipsDAGToDAGISel(TM, OL) {}
 
 private:
   std::pair<SDNode *, SDNode *> selectMULT(SDNode *N, unsigned Opc,
@@ -47,7 +48,8 @@
   void initMips16SPAliasReg(MachineFunction &MF);
 };
 
-FunctionPass *createMips16ISelDag(MipsTargetMachine &TM);
+FunctionPass *createMips16ISelDag(MipsTargetMachine &TM,
+                                  CodeGenOpt::Level OptLevel);
 }
 
 #endif
Index: lib/Target/Mips/Mips16ISelDAGToDAG.cpp
===================================================================
--- lib/Target/Mips/Mips16ISelDAGToDAG.cpp
+++ lib/Target/Mips/Mips16ISelDAGToDAG.cpp
@@ -254,6 +254,7 @@
   return false;
 }
 
-FunctionPass *llvm::createMips16ISelDag(MipsTargetMachine &TM) {
-  return new Mips16DAGToDAGISel(TM);
+FunctionPass *llvm::createMips16ISelDag(MipsTargetMachine &TM,
+                                        CodeGenOpt::Level OptLevel) {
+  return new Mips16DAGToDAGISel(TM, OptLevel);
 }
Index: lib/Target/Mips/MipsISelDAGToDAG.h
===================================================================
--- lib/Target/Mips/MipsISelDAGToDAG.h
+++ lib/Target/Mips/MipsISelDAGToDAG.h
@@ -31,8 +31,8 @@
 
 class MipsDAGToDAGISel : public SelectionDAGISel {
 public:
-  explicit MipsDAGToDAGISel(MipsTargetMachine &TM)
-      : SelectionDAGISel(TM), Subtarget(nullptr) {}
+  explicit MipsDAGToDAGISel(MipsTargetMachine &TM, CodeGenOpt::Level OL)
+      : SelectionDAGISel(TM, OL), Subtarget(nullptr) {}
 
   // Pass Name
   const char *getPassName() const override {
Index: lib/Target/Mips/MipsSEISelDAGToDAG.h
===================================================================
--- lib/Target/Mips/MipsSEISelDAGToDAG.h
+++ lib/Target/Mips/MipsSEISelDAGToDAG.h
@@ -21,7 +21,8 @@
 class MipsSEDAGToDAGISel : public MipsDAGToDAGISel {
 
 public:
-  explicit MipsSEDAGToDAGISel(MipsTargetMachine &TM) : MipsDAGToDAGISel(TM) {}
+  explicit MipsSEDAGToDAGISel(MipsTargetMachine &TM, CodeGenOpt::Level OL)
+      : MipsDAGToDAGISel(TM, OL) {}
 
 private:
 
@@ -122,8 +123,8 @@
                                     std::vector<SDValue> &OutOps) override;
 };
 
-FunctionPass *createMipsSEISelDag(MipsTargetMachine &TM);
-
+FunctionPass *createMipsSEISelDag(MipsTargetMachine &TM,
+                                  CodeGenOpt::Level OptLevel);
 }
 
 #endif
Index: lib/Target/Mips/MipsSEISelDAGToDAG.cpp
===================================================================
--- lib/Target/Mips/MipsSEISelDAGToDAG.cpp
+++ lib/Target/Mips/MipsSEISelDAGToDAG.cpp
@@ -1009,6 +1009,7 @@
   return true;
 }
 
-FunctionPass *llvm::createMipsSEISelDag(MipsTargetMachine &TM) {
-  return new MipsSEDAGToDAGISel(TM);
+FunctionPass *llvm::createMipsSEISelDag(MipsTargetMachine &TM,
+                                        CodeGenOpt::Level OptLevel) {
+  return new MipsSEDAGToDAGISel(TM, OptLevel);
 }
Index: lib/Target/Mips/MipsTargetMachine.cpp
===================================================================
--- lib/Target/Mips/MipsTargetMachine.cpp
+++ lib/Target/Mips/MipsTargetMachine.cpp
@@ -229,8 +229,8 @@
 // the ISelDag to gen Mips code.
 bool MipsPassConfig::addInstSelector() {
   addPass(createMipsModuleISelDagPass(getMipsTargetMachine()));
-  addPass(createMips16ISelDag(getMipsTargetMachine()));
-  addPass(createMipsSEISelDag(getMipsTargetMachine()));
+  addPass(createMips16ISelDag(getMipsTargetMachine(), getOptLevel()));
+  addPass(createMipsSEISelDag(getMipsTargetMachine(), getOptLevel()));
   return false;
 }
 
Index: test/CodeGen/Mips/selectiondag-optlevel.ll
===================================================================
--- /dev/null
+++ test/CodeGen/Mips/selectiondag-optlevel.ll
@@ -0,0 +1,22 @@
+; RUN: llc -march=mips -fast-isel=false -O0 < %s 2>&1 | FileCheck %s -check-prefix=O0
+; RUN: llc -march=mips -fast-isel=false -O2 < %s 2>&1 | FileCheck %s -check-prefix=O2
+
+; At -O0, DAGCombine won't try to merge these consecutive loads but it will at
+; -O2.
+
+define void @foo() nounwind {
+entry:
+  %0 = alloca [2 x i8], align 32
+  %1 = getelementptr inbounds [2 x i8], [2 x i8]* %0, i32 0, i32 0
+  store i8 1, i8* %1
+  %2 = getelementptr inbounds [2 x i8], [2 x i8]* %0, i32 0, i32 1
+  store i8 1, i8* %2
+  ret void
+}
+
+; O0: addiu $[[REG:[0-9]+]], $zero, 1
+; O0-DAG: sb $[[REG]], 0($sp)
+; O0-DAG: sb $[[REG]], 1($sp)
+
+; O2: addiu $[[REG:[0-9]+]], $zero, 257
+; O2: sh $[[REG]], 0($sp)