diff --git a/llvm/include/llvm/Analysis/AliasAnalysis.h b/llvm/include/llvm/Analysis/AliasAnalysis.h
--- a/llvm/include/llvm/Analysis/AliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/AliasAnalysis.h
@@ -42,9 +42,9 @@
 #include "llvm/ADT/Sequence.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Analysis/MemoryLocation.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/Pass.h"
+#include "llvm/Support/ModRef.h"
 #include <cstdint>
 #include <functional>
 #include <memory>
diff --git a/llvm/include/llvm/IR/ModRef.h b/llvm/include/llvm/Support/ModRef.h
rename from llvm/include/llvm/IR/ModRef.h
rename to llvm/include/llvm/Support/ModRef.h
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -37,7 +37,6 @@
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Metadata.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/Value.h"
@@ -45,6 +44,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/ModRef.h"
 #include "llvm/Support/SaveAndRestore.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -55,7 +55,6 @@
 #include "llvm/IR/IntrinsicsARM.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Metadata.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/ModuleSummaryIndex.h"
 #include "llvm/IR/Operator.h"
@@ -72,6 +71,7 @@
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/ModRef.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -61,7 +61,6 @@
 #include "llvm/IR/Function.h"
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Instructions.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/MC/LaneBitmask.h"
 #include "llvm/MC/MCAsmInfo.h"
@@ -74,6 +73,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/LowLevelTypeImpl.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/ModRef.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetMachine.h"
 #include <algorithm>
diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -26,10 +26,10 @@
 #include "llvm/Config/llvm-config.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/LLVMContext.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/IR/Type.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/ModRef.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -51,7 +51,6 @@
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/MDBuilder.h"
 #include "llvm/IR/Metadata.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/SymbolTableListTraits.h"
@@ -64,6 +63,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/ModRef.h"
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -30,7 +30,6 @@
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/MDBuilder.h"
 #include "llvm/IR/Metadata.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/Type.h"
@@ -39,6 +38,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/ModRef.h"
 #include "llvm/Support/TypeSize.h"
 #include <algorithm>
 #include <cassert>
diff --git a/llvm/lib/Target/AMDGPU/AMDGPULibFunc.cpp b/llvm/lib/Target/AMDGPU/AMDGPULibFunc.cpp
--- a/llvm/lib/Target/AMDGPU/AMDGPULibFunc.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULibFunc.cpp
@@ -17,10 +17,10 @@
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/ValueSymbolTable.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ModRef.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -34,8 +34,8 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/IntrinsicsAMDGPU.h"
 #include "llvm/IR/IntrinsicsR600.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ModRef.h"
 #include "llvm/Support/KnownBits.h"
 
 using namespace llvm;
diff --git a/llvm/lib/Target/Mips/Mips16HardFloat.cpp b/llvm/lib/Target/Mips/Mips16HardFloat.cpp
--- a/llvm/lib/Target/Mips/Mips16HardFloat.cpp
+++ b/llvm/lib/Target/Mips/Mips16HardFloat.cpp
@@ -12,10 +12,10 @@
 
 #include "MipsTargetMachine.h"
 #include "llvm/CodeGen/TargetPassConfig.h"
-#include "llvm/IR/ModRef.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ModRef.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <string>
diff --git a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
--- a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -2998,7 +2998,7 @@
     // chain.
     if (Int.IS.RetVTs.empty())
       Operator = getDAGPatterns().get_intrinsic_void_sdnode();
-    else if (Int.ModRef != CodeGenIntrinsic::NoMem || Int.hasSideEffects)
+    else if (!Int.ME.doesNotAccessMemory() || Int.hasSideEffects)
       // Has side-effects, requires chain.
       Operator = getDAGPatterns().get_intrinsic_w_chain_sdnode();
     else // Otherwise, no chain.
@@ -3637,16 +3637,17 @@
     if (N->NodeHasProperty(SDNPHasChain, CDP)) hasChain = true;
 
     if (const CodeGenIntrinsic *IntInfo = N->getIntrinsicInfo(CDP)) {
+      ModRefInfo MR = IntInfo->ME.getModRef();
       // If this is an intrinsic, analyze it.
-      if (IntInfo->ModRef & CodeGenIntrinsic::MR_Ref)
-        mayLoad = true;// These may load memory.
+      if (isRefSet(MR))
+        mayLoad = true; // These may load memory.
 
-      if (IntInfo->ModRef & CodeGenIntrinsic::MR_Mod)
-        mayStore = true;// Intrinsics that can write to memory are 'mayStore'.
+      if (isModSet(MR))
+        mayStore = true; // Intrinsics that can write to memory are 'mayStore'.
 
-      if (IntInfo->ModRef >= CodeGenIntrinsic::ReadWriteMem ||
-          IntInfo->hasSideEffects)
-        // ReadWriteMem intrinsics can have other strange effects.
+      // Consider intrinsics that don't specify any restrictions on memory
+      // effects as having a side-effect.
+      if (IntInfo->ME == MemoryEffects::unknown() || IntInfo->hasSideEffects)
         hasSideEffects = true;
     }
   }
diff --git a/llvm/utils/TableGen/CodeGenIntrinsics.h b/llvm/utils/TableGen/CodeGenIntrinsics.h
--- a/llvm/utils/TableGen/CodeGenIntrinsics.h
+++ b/llvm/utils/TableGen/CodeGenIntrinsics.h
@@ -16,6 +16,7 @@
 #include "SDNodeProperties.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/MachineValueType.h"
+#include "llvm/Support/ModRef.h"
 #include <string>
 #include <vector>
 
@@ -58,51 +59,8 @@
 
   IntrinsicSignature IS;
 
-  /// Bit flags describing the type (ref/mod) and location of memory
-  /// accesses that may be performed by the intrinsics. Analogous to
-  /// \c FunctionModRefBehaviour.
-  enum ModRefBits {
-    /// The intrinsic may access memory that is otherwise inaccessible via
-    /// LLVM IR.
-    MR_InaccessibleMem = 1,
-
-    /// The intrinsic may access memory through pointer arguments.
-    /// LLVM IR.
-    MR_ArgMem = 2,
-
-    /// The intrinsic may access memory anywhere, i.e. it is not restricted
-    /// to access through pointer arguments.
-    MR_Anywhere = 4 | MR_ArgMem | MR_InaccessibleMem,
-
-    /// The intrinsic may read memory.
-    MR_Ref = 8,
-
-    /// The intrinsic may write memory.
-    MR_Mod = 16,
-
-    /// The intrinsic may both read and write memory.
-    MR_ModRef = MR_Ref | MR_Mod,
-  };
-
-  /// Memory mod/ref behavior of this intrinsic, corresponding to intrinsic
-  /// properties (IntrReadMem, IntrArgMemOnly, etc.).
-  enum ModRefBehavior {
-    NoMem = 0,
-    ReadArgMem = MR_Ref | MR_ArgMem,
-    ReadInaccessibleMem = MR_Ref | MR_InaccessibleMem,
-    ReadInaccessibleMemOrArgMem = MR_Ref | MR_ArgMem | MR_InaccessibleMem,
-    ReadMem = MR_Ref | MR_Anywhere,
-    WriteArgMem = MR_Mod | MR_ArgMem,
-    WriteInaccessibleMem = MR_Mod | MR_InaccessibleMem,
-    WriteInaccessibleMemOrArgMem = MR_Mod | MR_ArgMem | MR_InaccessibleMem,
-    WriteMem = MR_Mod | MR_Anywhere,
-    ReadWriteArgMem = MR_ModRef | MR_ArgMem,
-    ReadWriteInaccessibleMem = MR_ModRef | MR_InaccessibleMem,
-    ReadWriteInaccessibleMemOrArgMem = MR_ModRef | MR_ArgMem |
-                                       MR_InaccessibleMem,
-    ReadWriteMem = MR_ModRef | MR_Anywhere,
-  };
-  ModRefBehavior ModRef;
+  /// Memory effects of the intrinsic.
+  MemoryEffects ME = MemoryEffects::unknown();
 
   /// SDPatternOperator Properties applied to the intrinsic.
   unsigned Properties;
diff --git a/llvm/utils/TableGen/CodeGenTarget.cpp b/llvm/utils/TableGen/CodeGenTarget.cpp
--- a/llvm/utils/TableGen/CodeGenTarget.cpp
+++ b/llvm/utils/TableGen/CodeGenTarget.cpp
@@ -668,7 +668,6 @@
   TheDef = R;
   std::string DefName = std::string(R->getName());
   ArrayRef<SMLoc> DefLoc = R->getLoc();
-  ModRef = ReadWriteMem;
   Properties = 0;
   isOverloaded = false;
   isCommutative = false;
@@ -842,26 +841,25 @@
 
 void CodeGenIntrinsic::setProperty(Record *R) {
   if (R->getName() == "IntrNoMem")
-    ModRef = NoMem;
+    ME = MemoryEffects::none();
   else if (R->getName() == "IntrReadMem") {
-    if (!(ModRef & MR_Ref))
+    if (ME.onlyWritesMemory())
       PrintFatalError(TheDef->getLoc(),
                       Twine("IntrReadMem cannot be used after IntrNoMem or "
                             "IntrWriteMem. Default is ReadWrite"));
-    ModRef = ModRefBehavior(ModRef & ~MR_Mod);
+    ME &= MemoryEffects::readOnly();
   } else if (R->getName() == "IntrWriteMem") {
-    if (!(ModRef & MR_Mod))
+    if (ME.onlyReadsMemory())
       PrintFatalError(TheDef->getLoc(),
                       Twine("IntrWriteMem cannot be used after IntrNoMem or "
                             "IntrReadMem. Default is ReadWrite"));
-    ModRef = ModRefBehavior(ModRef & ~MR_Ref);
+    ME &= MemoryEffects::writeOnly();
   } else if (R->getName() == "IntrArgMemOnly")
-    ModRef = ModRefBehavior((ModRef & ~MR_Anywhere) | MR_ArgMem);
+    ME &= MemoryEffects::argMemOnly();
   else if (R->getName() == "IntrInaccessibleMemOnly")
-    ModRef = ModRefBehavior((ModRef & ~MR_Anywhere) | MR_InaccessibleMem);
+    ME &= MemoryEffects::inaccessibleMemOnly();
   else if (R->getName() == "IntrInaccessibleMemOrArgMemOnly")
-    ModRef = ModRefBehavior((ModRef & ~MR_Anywhere) | MR_ArgMem |
-                            MR_InaccessibleMem);
+    ME &= MemoryEffects::inaccessibleOrArgMemOnly();
   else if (R->getName() == "Commutative")
     isCommutative = true;
   else if (R->getName() == "Throws")
diff --git a/llvm/utils/TableGen/IntrinsicEmitter.cpp b/llvm/utils/TableGen/IntrinsicEmitter.cpp
--- a/llvm/utils/TableGen/IntrinsicEmitter.cpp
+++ b/llvm/utils/TableGen/IntrinsicEmitter.cpp
@@ -642,8 +642,8 @@
     return R->hasSideEffects;
 
   // Try to order by readonly/readnone attribute.
-  CodeGenIntrinsic::ModRefBehavior LK = L->ModRef;
-  CodeGenIntrinsic::ModRefBehavior RK = R->ModRef;
+  uint32_t LK = L->ME.toIntValue();
+  uint32_t RK = R->ME.toIntValue();
   if (LK != RK) return (LK > RK);
 
   return None;
@@ -772,60 +772,13 @@
     if (Intrinsic.isSpeculatable)
       OS << "      Attribute::get(C, Attribute::Speculatable),\n";
 
-    switch (Intrinsic.ModRef) {
-    case CodeGenIntrinsic::NoMem:
-      if (Intrinsic.hasSideEffects)
-        break;
+    MemoryEffects ME = Intrinsic.ME;
+    // TODO: IntrHasSideEffects should affect not only readnone intrinsics.
+    if (ME.doesNotAccessMemory() && Intrinsic.hasSideEffects)
+      ME = MemoryEffects::unknown();
+    if (ME != MemoryEffects::unknown()) {
       OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::none()),\n";
-      break;
-    case CodeGenIntrinsic::ReadArgMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::argMemOnly(ModRefInfo::Ref)),\n";
-      break;
-    case CodeGenIntrinsic::ReadMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::readOnly()),\n";
-      break;
-    case CodeGenIntrinsic::ReadInaccessibleMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::inaccessibleMemOnly(ModRefInfo::Ref)),\n";
-      break;
-    case CodeGenIntrinsic::ReadInaccessibleMemOrArgMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::inaccessibleOrArgMemOnly(ModRefInfo::Ref)),\n";
-      break;
-      break;
-    case CodeGenIntrinsic::WriteArgMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::argMemOnly(ModRefInfo::Mod)),\n";
-      break;
-    case CodeGenIntrinsic::WriteMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::writeOnly()),\n";
-      break;
-    case CodeGenIntrinsic::WriteInaccessibleMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::inaccessibleMemOnly(ModRefInfo::Mod)),\n";
-      break;
-    case CodeGenIntrinsic::WriteInaccessibleMemOrArgMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::inaccessibleOrArgMemOnly(ModRefInfo::Mod)),\n";
-      break;
-    case CodeGenIntrinsic::ReadWriteArgMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::argMemOnly(ModRefInfo::ModRef)),\n";
-      break;
-    case CodeGenIntrinsic::ReadWriteInaccessibleMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::inaccessibleMemOnly(ModRefInfo::ModRef)),\n";
-      break;
-    case CodeGenIntrinsic::ReadWriteInaccessibleMemOrArgMem:
-      OS << "      Attribute::getWithMemoryEffects(C, "
-         << "MemoryEffects::inaccessibleOrArgMemOnly(ModRefInfo::ModRef)),\n";
-      break;
-    case CodeGenIntrinsic::ReadWriteMem:
-      break;
+         << "MemoryEffects::createFromIntValue(" << ME.toIntValue() << ")),\n";
     }
     OS << "    });\n";
   }
@@ -885,7 +838,7 @@
     }
 
     if (!Intrinsic.canThrow ||
-        (Intrinsic.ModRef != CodeGenIntrinsic::ReadWriteMem &&
+        (Intrinsic.ME != MemoryEffects::unknown() &&
          !Intrinsic.hasSideEffects) ||
         Intrinsic.isNoReturn || Intrinsic.isNoCallback || Intrinsic.isNoSync ||
         Intrinsic.isNoFree || Intrinsic.isWillReturn || Intrinsic.isCold ||