Index: llvm/trunk/include/llvm/CodeGen/MachineInstr.h
===================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineInstr.h
+++ llvm/trunk/include/llvm/CodeGen/MachineInstr.h
@@ -1149,10 +1149,11 @@
   //
   // Debugging support
   //
-  void print(raw_ostream &OS, bool SkipOpers = false) const;
-  void print(raw_ostream &OS, ModuleSlotTracker &MST,
-             bool SkipOpers = false) const;
-  void dump() const;
+  void print(raw_ostream &OS, bool SkipOpers = false,
+             const TargetInstrInfo *TII = nullptr) const;
+  void print(raw_ostream &OS, ModuleSlotTracker &MST, bool SkipOpers = false,
+             const TargetInstrInfo *TII = nullptr) const;
+  void dump(const TargetInstrInfo *TII = nullptr) const;
 
   //===--------------------------------------------------------------------===//
   // Accessors used to build up machine instructions.
Index: llvm/trunk/lib/CodeGen/MachineCombiner.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/MachineCombiner.cpp
+++ llvm/trunk/lib/CodeGen/MachineCombiner.cpp
@@ -135,7 +135,7 @@
   // are tracked in the InstrIdxForVirtReg map depth is looked up in InstrDepth
   for (auto *InstrPtr : InsInstrs) { // for each Use
     unsigned IDepth = 0;
-    DEBUG(dbgs() << "NEW INSTR "; InstrPtr->dump(); dbgs() << "\n";);
+    DEBUG(dbgs() << "NEW INSTR "; InstrPtr->dump(TII); dbgs() << "\n";);
     for (const MachineOperand &MO : InstrPtr->operands()) {
       // Check for virtual register operand.
       if (!(MO.isReg() && TargetRegisterInfo::isVirtualRegister(MO.getReg())))
Index: llvm/trunk/lib/CodeGen/MachineInstr.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/MachineInstr.cpp
+++ llvm/trunk/lib/CodeGen/MachineInstr.cpp
@@ -1692,29 +1692,30 @@
   }
 }
 
-LLVM_DUMP_METHOD void MachineInstr::dump() const {
+LLVM_DUMP_METHOD void MachineInstr::dump(const TargetInstrInfo *TII) const {
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-  dbgs() << "  " << *this;
+  dbgs() << "  ";
+  print(dbgs(), false /* SkipOpers */, TII);
 #endif
 }
 
-void MachineInstr::print(raw_ostream &OS, bool SkipOpers) const {
+void MachineInstr::print(raw_ostream &OS, bool SkipOpers,
+                         const TargetInstrInfo *TII) const {
   const Module *M = nullptr;
   if (const MachineBasicBlock *MBB = getParent())
     if (const MachineFunction *MF = MBB->getParent())
       M = MF->getFunction()->getParent();
 
   ModuleSlotTracker MST(M);
-  print(OS, MST, SkipOpers);
+  print(OS, MST, SkipOpers, TII);
 }
 
 void MachineInstr::print(raw_ostream &OS, ModuleSlotTracker &MST,
-                         bool SkipOpers) const {
+                         bool SkipOpers, const TargetInstrInfo *TII) const {
   // We can be a bit tidier if we know the MachineFunction.
   const MachineFunction *MF = nullptr;
   const TargetRegisterInfo *TRI = nullptr;
   const MachineRegisterInfo *MRI = nullptr;
-  const TargetInstrInfo *TII = nullptr;
   const TargetIntrinsicInfo *IntrinsicInfo = nullptr;
 
   if (const MachineBasicBlock *MBB = getParent()) {
@@ -1722,7 +1723,8 @@
     if (MF) {
       MRI = &MF->getRegInfo();
       TRI = MF->getSubtarget().getRegisterInfo();
-      TII = MF->getSubtarget().getInstrInfo();
+      if (!TII)
+        TII = MF->getSubtarget().getInstrInfo();
       IntrinsicInfo = MF->getTarget().getIntrinsicInfo();
     }
   }
Index: llvm/trunk/test/CodeGen/AArch64/machine-combiner-madd.ll
===================================================================
--- llvm/trunk/test/CodeGen/AArch64/machine-combiner-madd.ll
+++ llvm/trunk/test/CodeGen/AArch64/machine-combiner-madd.ll
@@ -7,6 +7,11 @@
 ; RUN: llc -mtriple=aarch64-linux-gnu -mcpu=exynos-m2  < %s | FileCheck %s
 ; RUN: llc -mtriple=aarch64-linux-gnu -mcpu=kryo       < %s | FileCheck %s
 ; RUN: llc -mtriple=aarch64-linux-gnu -mcpu=vulcan     < %s | FileCheck %s
+; RUN: llc -mtriple=aarch64-linux-gnu -mcpu=cortex-a57 -debug-only=machine-combiner < %s 2>&1 > /dev/null | FileCheck %s --check-prefix COMBINE-DUMP
+
+; The machine-combiner debugging dumps should print the new instruction.
+; COMBINE-DUMP: NEW INSTR{{.*}}MADDXrrr
+; COMBINE-DUMP-NOT: NEW INSTR{{.*}}UNKNOWN
 
 ; Make sure that inst-combine fuses the multiply add in the addressing mode of
 ; the load.