Index: llvm/trunk/include/llvm/CodeGen/MachineMemOperand.h
===================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineMemOperand.h
+++ llvm/trunk/include/llvm/CodeGen/MachineMemOperand.h
@@ -114,6 +114,9 @@
     MOInvariant = 1u << 5,
 
     // Reserved for use by target-specific passes.
+    // Targets may override getSerializableMachineMemOperandTargetFlags() to
+    // enable MIR serialization/parsing of these flags.  If more of these flags
+    // are added, the MIR printing/parsing code will need to be updated as well.
     MOTargetFlag1 = 1u << 6,
     MOTargetFlag2 = 1u << 7,
     MOTargetFlag3 = 1u << 8,
Index: llvm/trunk/include/llvm/Target/TargetInstrInfo.h
===================================================================
--- llvm/trunk/include/llvm/Target/TargetInstrInfo.h
+++ llvm/trunk/include/llvm/Target/TargetInstrInfo.h
@@ -1545,6 +1545,16 @@
     return None;
   }
 
+  /// Return an array that contains the MMO target flag values and their
+  /// names.
+  ///
+  /// MIR Serialization is able to serialize only the MMO target flags that are
+  /// defined by this method.
+  virtual ArrayRef<std::pair<MachineMemOperand::Flags, const char *>>
+  getSerializableMachineMemOperandTargetFlags() const {
+    return None;
+  }
+
   /// Determines whether \p Inst is a tail call instruction. Override this
   /// method on targets that do not properly set MCID::Return and MCID::Call on
   /// tail call instructions."
Index: llvm/trunk/lib/CodeGen/MIRParser/MILexer.h
===================================================================
--- llvm/trunk/lib/CodeGen/MIRParser/MILexer.h
+++ llvm/trunk/lib/CodeGen/MIRParser/MILexer.h
@@ -169,7 +169,8 @@
 
   bool isMemoryOperandFlag() const {
     return Kind == kw_volatile || Kind == kw_non_temporal ||
-           Kind == kw_dereferenceable || Kind == kw_invariant;
+           Kind == kw_dereferenceable || Kind == kw_invariant ||
+           Kind == StringConstant;
   }
 
   bool is(TokenKind K) const { return Kind == K; }
Index: llvm/trunk/lib/CodeGen/MIRParser/MIParser.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/MIRParser/MIParser.cpp
+++ llvm/trunk/lib/CodeGen/MIRParser/MIParser.cpp
@@ -141,6 +141,8 @@
   StringMap<unsigned> Names2DirectTargetFlags;
   /// Maps from direct target flag names to the bitmask target flag values.
   StringMap<unsigned> Names2BitmaskTargetFlags;
+  /// Maps from MMO target flag names to MMO target flag values.
+  StringMap<MachineMemOperand::Flags> Names2MMOTargetFlags;
 
 public:
   MIParser(PerFunctionMIParsingState &PFS, SMDiagnostic &Error,
@@ -320,6 +322,14 @@
   /// Return true if the name isn't a name of a bitmask target flag.
   bool getBitmaskTargetFlag(StringRef Name, unsigned &Flag);
 
+  void initNames2MMOTargetFlags();
+
+  /// Try to convert a name of a MachineMemOperand target flag to the
+  /// corresponding target flag.
+  ///
+  /// Return true if the name isn't a name of a target MMO flag.
+  bool getMMOTargetFlag(StringRef Name, MachineMemOperand::Flags &Flag);
+
   /// parseStringConstant
   ///   ::= StringConstant
   bool parseStringConstant(std::string &Result);
@@ -2039,7 +2049,14 @@
   case MIToken::kw_invariant:
     Flags |= MachineMemOperand::MOInvariant;
     break;
-  // TODO: parse the target specific memory operand flags.
+  case MIToken::StringConstant: {
+    MachineMemOperand::Flags TF;
+    if (getMMOTargetFlag(Token.stringValue(), TF))
+      return error("use of undefined target MMO flag '" + Token.stringValue() +
+                   "'");
+    Flags |= TF;
+    break;
+  }
   default:
     llvm_unreachable("The current token should be a memory operand flag");
   }
@@ -2480,6 +2497,27 @@
   return false;
 }
 
+void MIParser::initNames2MMOTargetFlags() {
+  if (!Names2MMOTargetFlags.empty())
+    return;
+  const auto *TII = MF.getSubtarget().getInstrInfo();
+  assert(TII && "Expected target instruction info");
+  auto Flags = TII->getSerializableMachineMemOperandTargetFlags();
+  for (const auto &I : Flags)
+    Names2MMOTargetFlags.insert(
+        std::make_pair(StringRef(I.second), I.first));
+}
+
+bool MIParser::getMMOTargetFlag(StringRef Name,
+                                MachineMemOperand::Flags &Flag) {
+  initNames2MMOTargetFlags();
+  auto FlagInfo = Names2MMOTargetFlags.find(Name);
+  if (FlagInfo == Names2MMOTargetFlags.end())
+    return true;
+  Flag = FlagInfo->second;
+  return false;
+}
+
 bool MIParser::parseStringConstant(std::string &Result) {
   if (Token.isNot(MIToken::StringConstant))
     return error("expected string constant");
Index: llvm/trunk/lib/CodeGen/MIRPrinter.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/MIRPrinter.cpp
+++ llvm/trunk/lib/CodeGen/MIRPrinter.cpp
@@ -165,7 +165,8 @@
   void print(const MachineOperand &Op, const TargetRegisterInfo *TRI,
              unsigned I, bool ShouldPrintRegisterTies,
              LLT TypeToPrint, bool IsDef = false);
-  void print(const LLVMContext &Context, const MachineMemOperand &Op);
+  void print(const LLVMContext &Context, const TargetInstrInfo &TII,
+             const MachineMemOperand &Op);
   void printSyncScope(const LLVMContext &Context, SyncScope::ID SSID);
 
   void print(const MCCFIInstruction &CFI, const TargetRegisterInfo *TRI);
@@ -740,7 +741,7 @@
     for (const auto *Op : MI.memoperands()) {
       if (NeedComma)
         OS << ", ";
-      print(Context, *Op);
+      print(Context, *TII, *Op);
       NeedComma = true;
     }
   }
@@ -1036,9 +1037,20 @@
   }
 }
 
-void MIPrinter::print(const LLVMContext &Context, const MachineMemOperand &Op) {
+static const char *getTargetMMOFlagName(const TargetInstrInfo &TII,
+                                        unsigned TMMOFlag) {
+  auto Flags = TII.getSerializableMachineMemOperandTargetFlags();
+  for (const auto &I : Flags) {
+    if (I.first == TMMOFlag) {
+      return I.second;
+    }
+  }
+  return nullptr;
+}
+
+void MIPrinter::print(const LLVMContext &Context, const TargetInstrInfo &TII,
+                      const MachineMemOperand &Op) {
   OS << '(';
-  // TODO: Print operand's target specific flags.
   if (Op.isVolatile())
     OS << "volatile ";
   if (Op.isNonTemporal())
@@ -1047,6 +1059,15 @@
     OS << "dereferenceable ";
   if (Op.isInvariant())
     OS << "invariant ";
+  if (Op.getFlags() & MachineMemOperand::MOTargetFlag1)
+    OS << '"' << getTargetMMOFlagName(TII, MachineMemOperand::MOTargetFlag1)
+       << "\" ";
+  if (Op.getFlags() & MachineMemOperand::MOTargetFlag2)
+    OS << '"' << getTargetMMOFlagName(TII, MachineMemOperand::MOTargetFlag2)
+       << "\" ";
+  if (Op.getFlags() & MachineMemOperand::MOTargetFlag3)
+    OS << '"' << getTargetMMOFlagName(TII, MachineMemOperand::MOTargetFlag3)
+       << "\" ";
   if (Op.isLoad())
     OS << "load ";
   else {
Index: llvm/trunk/lib/CodeGen/MachineInstr.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/MachineInstr.cpp
+++ llvm/trunk/lib/CodeGen/MachineInstr.cpp
@@ -752,6 +752,12 @@
     OS << "(dereferenceable)";
   if (isInvariant())
     OS << "(invariant)";
+  if (getFlags() & MOTargetFlag1)
+    OS << "(flag1)";
+  if (getFlags() & MOTargetFlag2)
+    OS << "(flag2)";
+  if (getFlags() & MOTargetFlag3)
+    OS << "(flag3)";
 }
 
 //===----------------------------------------------------------------------===//
Index: llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.h
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.h
+++ llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.h
@@ -289,6 +289,8 @@
   getSerializableDirectMachineOperandTargetFlags() const override;
   ArrayRef<std::pair<unsigned, const char *>>
   getSerializableBitmaskMachineOperandTargetFlags() const override;
+  ArrayRef<std::pair<MachineMemOperand::Flags, const char *>>
+  getSerializableMachineMemOperandTargetFlags() const override;
 
   bool isFunctionSafeToOutlineFrom(MachineFunction &MF) const override;
   unsigned getOutliningBenefit(size_t SequenceSize, size_t Occurrences,
Index: llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -4430,6 +4430,13 @@
   return makeArrayRef(TargetFlags);
 }
 
+ArrayRef<std::pair<MachineMemOperand::Flags, const char *>>
+AArch64InstrInfo::getSerializableMachineMemOperandTargetFlags() const {
+  static const std::pair<MachineMemOperand::Flags, const char *> TargetFlags[] =
+      {{MOSuppressPair, "aarch64-suppress-pair"}};
+  return makeArrayRef(TargetFlags);
+}
+
 unsigned AArch64InstrInfo::getOutliningBenefit(size_t SequenceSize,
                                                size_t Occurrences,
                                                bool CanBeTailCall) const {
Index: llvm/trunk/test/CodeGen/MIR/AArch64/invalid-target-memoperands.mir
===================================================================
--- llvm/trunk/test/CodeGen/MIR/AArch64/invalid-target-memoperands.mir
+++ llvm/trunk/test/CodeGen/MIR/AArch64/invalid-target-memoperands.mir
@@ -0,0 +1,19 @@
+# RUN: not llc -mtriple=aarch64-none-linux-gnu -run-pass none -o /dev/null %s 2>&1 | FileCheck %s
+
+--- |
+
+  define void @target_memoperands_error() {
+    ret void
+  }
+
+...
+---
+name:            target_memoperands_error
+body: |
+  bb.0:
+
+    %0:_(p0) = COPY %x0
+  ; CHECK: [[@LINE+1]]:35: use of undefined target MMO flag 'aarch64-invalid'
+    %1:_(s64) = G_LOAD %0(p0) :: ("aarch64-invalid" load 8)
+    RET_ReallyLR
+...
Index: llvm/trunk/test/CodeGen/MIR/AArch64/target-memoperands.mir
===================================================================
--- llvm/trunk/test/CodeGen/MIR/AArch64/target-memoperands.mir
+++ llvm/trunk/test/CodeGen/MIR/AArch64/target-memoperands.mir
@@ -0,0 +1,22 @@
+# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass none -o - %s | FileCheck %s
+
+--- |
+
+  define void @target_memoperands() {
+    ret void
+  }
+
+...
+---
+# CHECK-LABEL: name: target_memoperands
+# CHECK: %1(s64) = G_LOAD %0(p0) :: ("aarch64-suppress-pair" load 8)
+# CHECK: G_STORE %1(s64), %0(p0) :: ("aarch64-suppress-pair" store 8)
+name:            target_memoperands
+body: |
+  bb.0:
+
+    %0:_(p0) = COPY %x0
+    %1:_(s64) = G_LOAD %0(p0) :: ("aarch64-suppress-pair" load 8)
+    G_STORE %1(s64), %0(p0) :: ("aarch64-suppress-pair" store 8)
+    RET_ReallyLR
+...