diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -1675,7 +1675,7 @@
 
         // Shuffle vector to get vec3.
         V = Builder.CreateShuffleVector(V, llvm::UndefValue::get(vec4Ty),
-                                        {0, 1, 2}, "extractVec");
+                                        ArrayRef<int>{0, 1, 2}, "extractVec");
         return EmitFromMemory(V, Ty);
       }
     }
diff --git a/llvm/include/llvm/ADT/ArrayRef.h b/llvm/include/llvm/ADT/ArrayRef.h
--- a/llvm/include/llvm/ADT/ArrayRef.h
+++ b/llvm/include/llvm/ADT/ArrayRef.h
@@ -532,11 +532,21 @@
     return LHS.equals(RHS);
   }
 
-  template<typename T>
+  template <typename T>
+  inline bool operator==(SmallVectorImpl<T> &LHS, ArrayRef<T> RHS) {
+    return ArrayRef<T>(LHS).equals(RHS);
+  }
+
+  template <typename T>
   inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
     return !(LHS == RHS);
   }
 
+  template <typename T>
+  inline bool operator!=(SmallVectorImpl<T> &LHS, ArrayRef<T> RHS) {
+    return !(LHS == RHS);
+  }
+
   /// @}
 
   template <typename T> hash_code hash_value(ArrayRef<T> S) {
diff --git a/llvm/include/llvm/Analysis/ConstantFolding.h b/llvm/include/llvm/Analysis/ConstantFolding.h
--- a/llvm/include/llvm/Analysis/ConstantFolding.h
+++ b/llvm/include/llvm/Analysis/ConstantFolding.h
@@ -119,10 +119,11 @@
 Constant *ConstantFoldExtractElementInstruction(Constant *Val, Constant *Idx);
 
 /// Attempt to constant fold a shufflevector instruction with the
-/// specified operands and indices.  The constant result is returned if
-/// successful; if not, null is returned.
+/// specified operands and mask.  See class ShuffleVectorInst for a description
+/// of the mask representation. The constant result is returned if successful;
+/// if not, null is returned.
 Constant *ConstantFoldShuffleVectorInstruction(Constant *V1, Constant *V2,
-                                               Constant *Mask);
+                                               ArrayRef<int> Mask);
 
 /// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
 /// produce if it is constant and determinable.  If this is not determinable,
diff --git a/llvm/include/llvm/Analysis/InstructionSimplify.h b/llvm/include/llvm/Analysis/InstructionSimplify.h
--- a/llvm/include/llvm/Analysis/InstructionSimplify.h
+++ b/llvm/include/llvm/Analysis/InstructionSimplify.h
@@ -230,7 +230,8 @@
                         const SimplifyQuery &Q);
 
 /// Given operands for a ShuffleVectorInst, fold the result or return null.
-Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, Constant *Mask,
+/// See class ShuffleVectorInst for a description of the mask representation.
+Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, ArrayRef<int> Mask,
                                  Type *RetTy, const SimplifyQuery &Q);
 
 //=== Helper functions for higher up the class hierarchy.
diff --git a/llvm/include/llvm/Analysis/TargetFolder.h b/llvm/include/llvm/Analysis/TargetFolder.h
--- a/llvm/include/llvm/Analysis/TargetFolder.h
+++ b/llvm/include/llvm/Analysis/TargetFolder.h
@@ -259,7 +259,7 @@
   }
 
   Constant *CreateShuffleVector(Constant *V1, Constant *V2,
-                                Constant *Mask) const override {
+                                ArrayRef<int> Mask) const override {
     return Fold(ConstantExpr::getShuffleVector(V1, V2, Mask));
   }
 
diff --git a/llvm/include/llvm/IR/ConstantFolder.h b/llvm/include/llvm/IR/ConstantFolder.h
--- a/llvm/include/llvm/IR/ConstantFolder.h
+++ b/llvm/include/llvm/IR/ConstantFolder.h
@@ -265,7 +265,7 @@
   }
 
   Constant *CreateShuffleVector(Constant *V1, Constant *V2,
-                                Constant *Mask) const override {
+                                ArrayRef<int> Mask) const override {
     return ConstantExpr::getShuffleVector(V1, V2, Mask);
   }
 
diff --git a/llvm/include/llvm/IR/Constants.h b/llvm/include/llvm/IR/Constants.h
--- a/llvm/include/llvm/IR/Constants.h
+++ b/llvm/include/llvm/IR/Constants.h
@@ -1206,7 +1206,8 @@
                                      Type *OnlyIfReducedTy = nullptr);
   static Constant *getInsertElement(Constant *Vec, Constant *Elt, Constant *Idx,
                                     Type *OnlyIfReducedTy = nullptr);
-  static Constant *getShuffleVector(Constant *V1, Constant *V2, Constant *Mask,
+  static Constant *getShuffleVector(Constant *V1, Constant *V2,
+                                    ArrayRef<int> Mask,
                                     Type *OnlyIfReducedTy = nullptr);
   static Constant *getExtractValue(Constant *Agg, ArrayRef<unsigned> Idxs,
                                    Type *OnlyIfReducedTy = nullptr);
@@ -1225,6 +1226,16 @@
   /// expression and return the list of indices.
   ArrayRef<unsigned> getIndices() const;
 
+  /// Assert that this is a shufflevector and return the mask. See class
+  /// ShuffleVectorInst for a description of the mask representation.
+  ArrayRef<int> getShuffleMask() const;
+
+  /// Assert that this is a shufflevector and return the mask.
+  ///
+  /// TODO: This is a temporary hack until we update the bitcode format for
+  /// shufflevector.
+  Constant *getShuffleMaskForBitcode() const;
+
   /// Return a string representation for an opcode.
   const char *getOpcodeName() const;
 
diff --git a/llvm/include/llvm/IR/IRBuilder.h b/llvm/include/llvm/IR/IRBuilder.h
--- a/llvm/include/llvm/IR/IRBuilder.h
+++ b/llvm/include/llvm/IR/IRBuilder.h
@@ -2617,17 +2617,25 @@
 
   Value *CreateShuffleVector(Value *V1, Value *V2, Value *Mask,
                              const Twine &Name = "") {
-    if (auto *V1C = dyn_cast<Constant>(V1))
-      if (auto *V2C = dyn_cast<Constant>(V2))
-        if (auto *MC = dyn_cast<Constant>(Mask))
-          return Insert(Folder.CreateShuffleVector(V1C, V2C, MC), Name);
-    return Insert(new ShuffleVectorInst(V1, V2, Mask), Name);
+    SmallVector<int, 16> IntMask;
+    ShuffleVectorInst::getShuffleMask(cast<Constant>(Mask), IntMask);
+    return CreateShuffleVector(V1, V2, IntMask, Name);
   }
 
-  Value *CreateShuffleVector(Value *V1, Value *V2, ArrayRef<uint32_t> IntMask,
+  Value *CreateShuffleVector(Value *V1, Value *V2, ArrayRef<uint32_t> Mask,
                              const Twine &Name = "") {
-    Value *Mask = ConstantDataVector::get(Context, IntMask);
-    return CreateShuffleVector(V1, V2, Mask, Name);
+    SmallVector<int, 16> IntMask;
+    IntMask.assign(Mask.begin(), Mask.end());
+    return CreateShuffleVector(V1, V2, IntMask, Name);
+  }
+
+  /// See class ShuffleVectorInst for a description of the mask representation.
+  Value *CreateShuffleVector(Value *V1, Value *V2, ArrayRef<int> Mask,
+                             const Twine &Name = "") {
+    if (auto *V1C = dyn_cast<Constant>(V1))
+      if (auto *V2C = dyn_cast<Constant>(V2))
+        return Insert(Folder.CreateShuffleVector(V1C, V2C, Mask), Name);
+    return Insert(new ShuffleVectorInst(V1, V2, Mask), Name);
   }
 
   Value *CreateExtractValue(Value *Agg,
diff --git a/llvm/include/llvm/IR/IRBuilderFolder.h b/llvm/include/llvm/IR/IRBuilderFolder.h
--- a/llvm/include/llvm/IR/IRBuilderFolder.h
+++ b/llvm/include/llvm/IR/IRBuilderFolder.h
@@ -129,7 +129,7 @@
   virtual Value *CreateInsertElement(Constant *Vec, Constant *NewElt,
                                      Constant *Idx) const = 0;
   virtual Value *CreateShuffleVector(Constant *V1, Constant *V2,
-                                     Constant *Mask) const = 0;
+                                     ArrayRef<int> Mask) const = 0;
   virtual Value *CreateExtractValue(Constant *Agg,
                                     ArrayRef<unsigned> IdxList) const = 0;
   virtual Value *CreateInsertValue(Constant *Agg, Constant *Val,
diff --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -1988,10 +1988,22 @@
 //                           ShuffleVectorInst Class
 //===----------------------------------------------------------------------===//
 
+constexpr int UndefMaskElem = -1;
+
 /// This instruction constructs a fixed permutation of two
 /// input vectors.
 ///
+/// For each element of the result vector, the shuffle mask selects an element
+/// from one of the input vectors to copy to the result. Non-negative elements
+/// in the mask represent an index into the concatenated pair of input vectors.
+/// UndefMaskElem (-1) specifies that the result element is undefined.
+///
+/// For scalable vectors, all the elements of the mask must be 0 or -1. This
+/// requirement may be relaxed in the future.
 class ShuffleVectorInst : public Instruction {
+  SmallVector<int, 4> ShuffleMask;
+  Constant *ShuffleMaskForBitcode;
+
 protected:
   // Note: Instruction needs to be a friend here to call cloneImpl.
   friend class Instruction;
@@ -2004,13 +2016,15 @@
                     Instruction *InsertBefor = nullptr);
   ShuffleVectorInst(Value *V1, Value *V2, Value *Mask,
                     const Twine &NameStr, BasicBlock *InsertAtEnd);
+  ShuffleVectorInst(Value *V1, Value *V2, ArrayRef<int> Mask,
+                    const Twine &NameStr = "",
+                    Instruction *InsertBefor = nullptr);
+  ShuffleVectorInst(Value *V1, Value *V2, ArrayRef<int> Mask,
+                    const Twine &NameStr, BasicBlock *InsertAtEnd);
 
-  // allocate space for exactly three operands
-  void *operator new(size_t s) {
-    return User::operator new(s, 3);
-  }
+  void *operator new(size_t s) { return User::operator new(s, 2); }
 
-  /// Swap the first 2 operands and adjust the mask to preserve the semantics
+  /// Swap the operands and adjust the mask to preserve the semantics
   /// of the instruction.
   void commute();
 
@@ -2018,6 +2032,8 @@
   /// formed with the specified operands.
   static bool isValidOperands(const Value *V1, const Value *V2,
                               const Value *Mask);
+  static bool isValidOperands(const Value *V1, const Value *V2,
+                              ArrayRef<int> Mask);
 
   /// Overload to return most specific vector type.
   ///
@@ -2028,36 +2044,33 @@
   /// Transparently provide more efficient getOperand methods.
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 
-  Constant *getMask() const {
-    return cast<Constant>(getOperand(2));
-  }
-
-  /// Return the shuffle mask value for the specified element of the mask.
-  /// Return -1 if the element is undef.
-  static int getMaskValue(const Constant *Mask, unsigned Elt);
-
   /// Return the shuffle mask value of this instruction for the given element
-  /// index. Return -1 if the element is undef.
-  int getMaskValue(unsigned Elt) const {
-    return getMaskValue(getMask(), Elt);
-  }
+  /// index. Return UndefMaskElem if the element is undef.
+  int getMaskValue(unsigned Elt) const { return ShuffleMask[Elt]; }
 
   /// Convert the input shuffle mask operand to a vector of integers. Undefined
-  /// elements of the mask are returned as -1.
+  /// elements of the mask are returned as UndefMaskElem.
   static void getShuffleMask(const Constant *Mask,
                              SmallVectorImpl<int> &Result);
 
   /// Return the mask for this instruction as a vector of integers. Undefined
-  /// elements of the mask are returned as -1.
+  /// elements of the mask are returned as UndefMaskElem.
   void getShuffleMask(SmallVectorImpl<int> &Result) const {
-    return getShuffleMask(getMask(), Result);
+    Result.assign(ShuffleMask.begin(), ShuffleMask.end());
   }
 
-  SmallVector<int, 16> getShuffleMask() const {
-    SmallVector<int, 16> Mask;
-    getShuffleMask(Mask);
-    return Mask;
-  }
+  /// Return the mask for this instruction, for use in bitcode.
+  ///
+  /// TODO: This is temporary until we decide a new bitcode encoding for
+  /// shufflevector.
+  Constant *getShuffleMaskForBitcode() const { return ShuffleMaskForBitcode; }
+
+  static Constant *convertShuffleMaskForBitcode(ArrayRef<int> Mask,
+                                                Type *ResultTy);
+
+  void setShuffleMask(ArrayRef<int> Mask);
+
+  ArrayRef<int> getShuffleMask() const { return ShuffleMask; }
 
   /// Return true if this shuffle returns a vector with a different number of
   /// elements than its source vectors.
@@ -2065,7 +2078,7 @@
   ///           shufflevector <4 x n> A, <4 x n> B, <1,2,3,4,5>
   bool changesLength() const {
     unsigned NumSourceElts = Op<0>()->getType()->getVectorNumElements();
-    unsigned NumMaskElts = getMask()->getType()->getVectorNumElements();
+    unsigned NumMaskElts = ShuffleMask.size();
     return NumSourceElts != NumMaskElts;
   }
 
@@ -2074,7 +2087,7 @@
   /// Example: shufflevector <2 x n> A, <2 x n> B, <1,2,3>
   bool increasesLength() const {
     unsigned NumSourceElts = Op<0>()->getType()->getVectorNumElements();
-    unsigned NumMaskElts = getMask()->getType()->getVectorNumElements();
+    unsigned NumMaskElts = ShuffleMask.size();
     return NumSourceElts < NumMaskElts;
   }
 
@@ -2095,7 +2108,7 @@
   /// Example: shufflevector <4 x n> A, <4 x n> B, <3,0,undef,3>
   /// TODO: Optionally allow length-changing shuffles.
   bool isSingleSource() const {
-    return !changesLength() && isSingleSourceMask(getMask());
+    return !changesLength() && isSingleSourceMask(ShuffleMask);
   }
 
   /// Return true if this shuffle mask chooses elements from exactly one source
@@ -2116,7 +2129,7 @@
   /// from its input vectors.
   /// Example: shufflevector <4 x n> A, <4 x n> B, <4,undef,6,undef>
   bool isIdentity() const {
-    return !changesLength() && isIdentityMask(getShuffleMask());
+    return !changesLength() && isIdentityMask(ShuffleMask);
   }
 
   /// Return true if this shuffle lengthens exactly one source vector with
@@ -2157,7 +2170,7 @@
   /// In that case, the shuffle is better classified as an identity shuffle.
   /// TODO: Optionally allow length-changing shuffles.
   bool isSelect() const {
-    return !changesLength() && isSelectMask(getMask());
+    return !changesLength() && isSelectMask(ShuffleMask);
   }
 
   /// Return true if this shuffle mask swaps the order of elements from exactly
@@ -2177,7 +2190,7 @@
   /// Example: shufflevector <4 x n> A, <4 x n> B, <3,undef,1,undef>
   /// TODO: Optionally allow length-changing shuffles.
   bool isReverse() const {
-    return !changesLength() && isReverseMask(getMask());
+    return !changesLength() && isReverseMask(ShuffleMask);
   }
 
   /// Return true if this shuffle mask chooses all elements with the same value
@@ -2199,7 +2212,7 @@
   /// TODO: Optionally allow length-changing shuffles.
   /// TODO: Optionally allow splats from other elements.
   bool isZeroEltSplat() const {
-    return !changesLength() && isZeroEltSplatMask(getMask());
+    return !changesLength() && isZeroEltSplatMask(ShuffleMask);
   }
 
   /// Return true if this shuffle mask is a transpose mask.
@@ -2248,7 +2261,7 @@
   /// exact specification.
   /// Example: shufflevector <4 x n> A, <4 x n> B, <0,4,2,6>
   bool isTranspose() const {
-    return !changesLength() && isTransposeMask(getMask());
+    return !changesLength() && isTransposeMask(ShuffleMask);
   }
 
   /// Return true if this shuffle mask is an extract subvector mask.
@@ -2267,7 +2280,7 @@
   /// Return true if this shuffle mask is an extract subvector mask.
   bool isExtractSubvectorMask(int &Index) const {
     int NumSrcElts = Op<0>()->getType()->getVectorNumElements();
-    return isExtractSubvectorMask(getMask(), NumSrcElts, Index);
+    return isExtractSubvectorMask(ShuffleMask, NumSrcElts, Index);
   }
 
   /// Change values in a shuffle permute mask assuming the two vector operands
@@ -2293,9 +2306,8 @@
 };
 
 template <>
-struct OperandTraits<ShuffleVectorInst> :
-  public FixedNumOperandTraits<ShuffleVectorInst, 3> {
-};
+struct OperandTraits<ShuffleVectorInst>
+    : public FixedNumOperandTraits<ShuffleVectorInst, 2> {};
 
 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ShuffleVectorInst, Value)
 
diff --git a/llvm/include/llvm/IR/NoFolder.h b/llvm/include/llvm/IR/NoFolder.h
--- a/llvm/include/llvm/IR/NoFolder.h
+++ b/llvm/include/llvm/IR/NoFolder.h
@@ -300,7 +300,7 @@
   }
 
   Instruction *CreateShuffleVector(Constant *V1, Constant *V2,
-                                   Constant *Mask) const override {
+                                   ArrayRef<int> Mask) const override {
     return new ShuffleVectorInst(V1, V2, Mask);
   }
 
diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -50,6 +50,10 @@
   return const_cast<Pattern &>(P).match(V);
 }
 
+template <typename Pattern> bool match(ArrayRef<int> Mask, const Pattern &P) {
+  return const_cast<Pattern &>(P).match(Mask);
+}
+
 template <typename SubPattern_t> struct OneUse_match {
   SubPattern_t SubPattern;
 
@@ -1350,12 +1354,69 @@
   return TwoOps_match<Val_t, Idx_t, Instruction::ExtractElement>(Val, Idx);
 }
 
-/// Matches ShuffleVectorInst.
+/// Matches shuffle.
+template <typename T0, typename T1, typename T2> struct Shuffle_match {
+  T0 Op1;
+  T1 Op2;
+  T2 Mask;
+
+  Shuffle_match(const T0 &Op1, const T1 &Op2, const T2 &Mask)
+      : Op1(Op1), Op2(Op2), Mask(Mask) {}
+
+  template <typename OpTy> bool match(OpTy *V) {
+    if (auto *I = dyn_cast<ShuffleVectorInst>(V)) {
+      return Op1.match(I->getOperand(0)) && Op2.match(I->getOperand(1)) &&
+             Mask.match(I->getShuffleMask());
+    }
+    return false;
+  }
+};
+
+struct m_Mask {
+  ArrayRef<int> &MaskRef;
+  m_Mask(ArrayRef<int> &MaskRef) : MaskRef(MaskRef) {}
+  bool match(ArrayRef<int> Mask) {
+    MaskRef = Mask;
+    return true;
+  }
+};
+
+struct m_ZeroMask {
+  bool match(ArrayRef<int> Mask) {
+    return all_of(Mask, [](int Elem) { return Elem == 0 || Elem == -1; });
+  }
+};
+
+struct m_SpecificMask {
+  ArrayRef<int> &MaskRef;
+  m_SpecificMask(ArrayRef<int> &MaskRef) : MaskRef(MaskRef) {}
+  bool match(ArrayRef<int> Mask) { return MaskRef == Mask; }
+};
+
+struct m_SplatOrUndefMask {
+  int &SplatIndex;
+  m_SplatOrUndefMask(int &SplatIndex) : SplatIndex(SplatIndex) {}
+  bool match(ArrayRef<int> Mask) {
+    auto First = find_if(Mask, [](int Elem) { return Elem != -1; });
+    if (First == Mask.end())
+      return false;
+    SplatIndex = *First;
+    return all_of(Mask,
+                  [First](int Elem) { return Elem == *First || Elem == -1; });
+  }
+};
+
+/// Matches ShuffleVectorInst independently of mask value.
+template <typename V1_t, typename V2_t>
+inline TwoOps_match<V1_t, V2_t, Instruction::ShuffleVector>
+m_ShuffleVector(const V1_t &v1, const V2_t &v2) {
+  return TwoOps_match<V1_t, V2_t, Instruction::ShuffleVector>(v1, v2);
+}
+
 template <typename V1_t, typename V2_t, typename Mask_t>
-inline ThreeOps_match<V1_t, V2_t, Mask_t, Instruction::ShuffleVector>
-m_ShuffleVector(const V1_t &v1, const V2_t &v2, const Mask_t &m) {
-  return ThreeOps_match<V1_t, V2_t, Mask_t, Instruction::ShuffleVector>(v1, v2,
-                                                                        m);
+inline Shuffle_match<V1_t, V2_t, Mask_t>
+m_ShuffleVector(const V1_t &v1, const V2_t &v2, const Mask_t &mask) {
+  return Shuffle_match<V1_t, V2_t, Mask_t>(v1, v2, mask);
 }
 
 /// Matches LoadInst.
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1066,7 +1066,8 @@
   case Instruction::InsertElement:
     return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]);
   case Instruction::ShuffleVector:
-    return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]);
+    return ConstantExpr::getShuffleVector(
+        Ops[0], Ops[1], cast<ShuffleVectorInst>(InstOrCE)->getShuffleMask());
   }
 }
 
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4439,36 +4439,31 @@
   return RootVec;
 }
 
-static Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, Constant *Mask,
-                                        Type *RetTy, const SimplifyQuery &Q,
+static Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1,
+                                        ArrayRef<int> Mask, Type *RetTy,
+                                        const SimplifyQuery &Q,
                                         unsigned MaxRecurse) {
-  if (isa<UndefValue>(Mask))
+  if (all_of(Mask, [](int Elem) { return Elem == UndefMaskElem; }))
     return UndefValue::get(RetTy);
 
   Type *InVecTy = Op0->getType();
-  ElementCount MaskEltCount = Mask->getType()->getVectorElementCount();
+  unsigned MaskNumElts = Mask.size();
   ElementCount InVecEltCount = InVecTy->getVectorElementCount();
 
-  assert(MaskEltCount.Scalable == InVecEltCount.Scalable &&
-         "vscale mismatch between input vector and mask");
-
-  bool Scalable = MaskEltCount.Scalable;
+  bool Scalable = InVecEltCount.Scalable;
 
   SmallVector<int, 32> Indices;
-  if (!Scalable) {
-    ShuffleVectorInst::getShuffleMask(Mask, Indices);
-    assert(MaskEltCount.Min == Indices.size() &&
-           "Size of Indices not same as number of mask elements?");
-  }
+  Indices.assign(Mask.begin(), Mask.end());
 
+  // Canonicalization: If mask does not select elements from an input vector,
+  // replace that input vector with undef.
   if (!Scalable) {
-    // Canonicalization: If mask does not select elements from an input vector,
-    // replace that input vector with undef.
     bool MaskSelects0 = false, MaskSelects1 = false;
-    for (unsigned i = 0; i != MaskEltCount.Min; ++i) {
+    unsigned InVecNumElts = InVecEltCount.Min;
+    for (unsigned i = 0; i != MaskNumElts; ++i) {
       if (Indices[i] == -1)
         continue;
-      if ((unsigned)Indices[i] < InVecEltCount.Min)
+      if ((unsigned)Indices[i] < InVecNumElts)
         MaskSelects0 = true;
       else
         MaskSelects1 = true;
@@ -4514,8 +4509,8 @@
       assert(isa<UndefValue>(Op1) && "Expected undef operand 1 for splat");
 
       // Shuffle mask undefs become undefined constant result elements.
-      SmallVector<Constant *, 16> VecC(MaskEltCount.Min, C);
-      for (unsigned i = 0; i != MaskEltCount.Min; ++i)
+      SmallVector<Constant *, 16> VecC(MaskNumElts, C);
+      for (unsigned i = 0; i != MaskNumElts; ++i)
         if (Indices[i] == -1)
           VecC[i] = UndefValue::get(C->getType());
       return ConstantVector::get(VecC);
@@ -4526,7 +4521,7 @@
   // value type is same as the input vectors' type.
   if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0))
     if (isa<UndefValue>(Op1) && RetTy == InVecTy &&
-        OpShuf->getMask()->getSplatValue())
+        is_splat(OpShuf->getShuffleMask()))
       return Op0;
 
   // All remaining transformation depend on the value of the mask, which is
@@ -4545,7 +4540,7 @@
   // shuffle. This handles simple identity shuffles as well as chains of
   // shuffles that may widen/narrow and/or move elements across lanes and back.
   Value *RootVec = nullptr;
-  for (unsigned i = 0; i != MaskEltCount.Min; ++i) {
+  for (unsigned i = 0; i != MaskNumElts; ++i) {
     // Note that recursion is limited for each vector element, so if any element
     // exceeds the limit, this will fail to simplify.
     RootVec =
@@ -4559,8 +4554,9 @@
 }
 
 /// Given operands for a ShuffleVectorInst, fold the result or return null.
-Value *llvm::SimplifyShuffleVectorInst(Value *Op0, Value *Op1, Constant *Mask,
-                                       Type *RetTy, const SimplifyQuery &Q) {
+Value *llvm::SimplifyShuffleVectorInst(Value *Op0, Value *Op1,
+                                       ArrayRef<int> Mask, Type *RetTy,
+                                       const SimplifyQuery &Q) {
   return ::SimplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit);
 }
 
@@ -5523,8 +5519,9 @@
   }
   case Instruction::ShuffleVector: {
     auto *SVI = cast<ShuffleVectorInst>(I);
-    Result = SimplifyShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
-                                       SVI->getMask(), SVI->getType(), Q);
+    Result =
+        SimplifyShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
+                                  SVI->getShuffleMask(), SVI->getType(), Q);
     break;
   }
   case Instruction::PHI:
diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -888,7 +888,7 @@
   for (unsigned i = 0, e = (1 << Level), val = !IsLeft; i != e; ++i, val += 2)
     Mask[i] = val;
 
-  SmallVector<int, 16> ActualMask = SI->getShuffleMask();
+  ArrayRef<int> ActualMask = SI->getShuffleMask();
   return Mask == ActualMask;
 }
 
@@ -1153,7 +1153,7 @@
     // Fill the rest of the mask with -1 for undef.
     std::fill(&ShuffleMask[MaskStart], ShuffleMask.end(), -1);
 
-    SmallVector<int, 16> Mask = Shuffle->getShuffleMask();
+    ArrayRef<int> Mask = Shuffle->getShuffleMask();
     if (ShuffleMask != Mask)
       return RK_None;
 
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -168,16 +168,16 @@
                                    APInt &DemandedLHS, APInt &DemandedRHS) {
   // The length of scalable vectors is unknown at compile time, thus we
   // cannot check their values
-  if (Shuf->getMask()->getType()->getVectorElementCount().Scalable)
+  if (Shuf->getType()->getVectorElementCount().Scalable)
     return false;
 
   int NumElts = Shuf->getOperand(0)->getType()->getVectorNumElements();
-  int NumMaskElts = Shuf->getMask()->getType()->getVectorNumElements();
+  int NumMaskElts = Shuf->getType()->getVectorNumElements();
   DemandedLHS = DemandedRHS = APInt::getNullValue(NumElts);
   if (DemandedElts.isNullValue())
     return true;
   // Simple case of a shuffle with zeroinitializer.
-  if (isa<ConstantAggregateZero>(Shuf->getMask())) {
+  if (all_of(Shuf->getShuffleMask(), [](int Elt) { return Elt == 0; })) {
     DemandedLHS.setBit(0);
     return true;
   }
diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp
--- a/llvm/lib/Analysis/VectorUtils.cpp
+++ b/llvm/lib/Analysis/VectorUtils.cpp
@@ -339,9 +339,9 @@
 
   // shuf (inselt ?, Splat, 0), ?, <0, undef, 0, ...>
   Value *Splat;
-  if (match(V, m_ShuffleVector(m_InsertElement(m_Value(), m_Value(Splat),
-                                               m_ZeroInt()),
-                               m_Value(), m_ZeroInt())))
+  if (match(V, m_ShuffleVector(
+                   m_InsertElement(m_Value(), m_Value(Splat), m_ZeroInt()),
+                   m_Value(), m_ZeroMask())))
     return Splat;
 
   return nullptr;
@@ -366,7 +366,7 @@
   if (auto *Shuf = dyn_cast<ShuffleVectorInst>(V)) {
     // FIXME: We can safely allow undefs here. If Index was specified, we will
     //        check that the mask elt is defined at the required index.
-    if (!Shuf->getMask()->getSplatValue())
+    if (!is_splat(Shuf->getShuffleMask()))
       return false;
 
     // Match any index.
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
@@ -3636,8 +3636,9 @@
         return Error(ID.Loc, "expected three operands to shufflevector");
       if (!ShuffleVectorInst::isValidOperands(Elts[0], Elts[1], Elts[2]))
         return Error(ID.Loc, "invalid operands to shufflevector");
-      ID.ConstantVal =
-                 ConstantExpr::getShuffleVector(Elts[0], Elts[1],Elts[2]);
+      SmallVector<int, 16> Mask;
+      ShuffleVectorInst::getShuffleMask(cast<Constant>(Elts[2]), Mask);
+      ID.ConstantVal = ConstantExpr::getShuffleVector(Elts[0], Elts[1], Mask);
     } else if (Opc == Instruction::ExtractElement) {
       if (Elts.size() != 2)
         return Error(ID.Loc, "expected two operands to extractelement");
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
@@ -2337,6 +2337,15 @@
   Type *CurFullTy = Type::getInt32Ty(Context);
   unsigned NextCstNo = ValueList.size();
 
+  struct DelayedShufTy {
+    VectorType *OpTy;
+    VectorType *RTy;
+    Type *CurFullTy;
+    uint64_t Op0Idx;
+    uint64_t Op1Idx;
+    uint64_t Op2Idx;
+  };
+  std::vector<DelayedShufTy> DelayedShuffles;
   while (true) {
     Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
     if (!MaybeEntry)
@@ -2353,6 +2362,29 @@
 
       // Once all the constants have been read, go through and resolve forward
       // references.
+      //
+      // We have to treat shuffles specially because they don't have three
+      // operands anymore.  We need to convert the shuffle mask into an array,
+      // and we can't convert a forward reference.
+      for (auto &DelayedShuffle : DelayedShuffles) {
+        VectorType *OpTy = DelayedShuffle.OpTy;
+        VectorType *RTy = DelayedShuffle.RTy;
+        uint64_t Op0Idx = DelayedShuffle.Op0Idx;
+        uint64_t Op1Idx = DelayedShuffle.Op1Idx;
+        uint64_t Op2Idx = DelayedShuffle.Op2Idx;
+        Constant *Op0 = ValueList.getConstantFwdRef(Op0Idx, OpTy);
+        Constant *Op1 = ValueList.getConstantFwdRef(Op1Idx, OpTy);
+        Type *ShufTy =
+            VectorType::get(Type::getInt32Ty(Context), RTy->getElementCount());
+        Constant *Op2 = ValueList.getConstantFwdRef(Op2Idx, ShufTy);
+        if (!ShuffleVectorInst::isValidOperands(Op0, Op1, Op2))
+          return error("Invalid shufflevector operands");
+        SmallVector<int, 16> Mask;
+        ShuffleVectorInst::getShuffleMask(Op2, Mask);
+        Value *V = ConstantExpr::getShuffleVector(Op0, Op1, Mask);
+        ValueList.assignValue(V, NextCstNo, DelayedShuffle.CurFullTy);
+        ++NextCstNo;
+      }
       ValueList.resolveConstantForwardRefs();
       return Error::success();
     case BitstreamEntry::Record:
@@ -2694,13 +2726,9 @@
       VectorType *OpTy = dyn_cast<VectorType>(CurTy);
       if (Record.size() < 3 || !OpTy)
         return error("Invalid record");
-      Constant *Op0 = ValueList.getConstantFwdRef(Record[0], OpTy);
-      Constant *Op1 = ValueList.getConstantFwdRef(Record[1], OpTy);
-      Type *ShufTy = VectorType::get(Type::getInt32Ty(Context),
-                                     OpTy->getElementCount());
-      Constant *Op2 = ValueList.getConstantFwdRef(Record[2], ShufTy);
-      V = ConstantExpr::getShuffleVector(Op0, Op1, Op2);
-      break;
+      DelayedShuffles.push_back(
+          {OpTy, OpTy, CurFullTy, Record[0], Record[1], Record[2]});
+      continue;
     }
     case bitc::CST_CODE_CE_SHUFVEC_EX: { // [opty, opval, opval, opval]
       VectorType *RTy = dyn_cast<VectorType>(CurTy);
@@ -2708,13 +2736,9 @@
         dyn_cast_or_null<VectorType>(getTypeByID(Record[0]));
       if (Record.size() < 4 || !RTy || !OpTy)
         return error("Invalid record");
-      Constant *Op0 = ValueList.getConstantFwdRef(Record[1], OpTy);
-      Constant *Op1 = ValueList.getConstantFwdRef(Record[2], OpTy);
-      Type *ShufTy = VectorType::get(Type::getInt32Ty(Context),
-                                     RTy->getElementCount());
-      Constant *Op2 = ValueList.getConstantFwdRef(Record[3], ShufTy);
-      V = ConstantExpr::getShuffleVector(Op0, Op1, Op2);
-      break;
+      DelayedShuffles.push_back(
+          {OpTy, RTy, CurFullTy, Record[1], Record[2], Record[3]});
+      continue;
     }
     case bitc::CST_CODE_CE_CMP: {     // CE_CMP: [opty, opval, opval, pred]
       if (Record.size() < 4)
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -2515,7 +2515,7 @@
         }
         Record.push_back(VE.getValueID(C->getOperand(0)));
         Record.push_back(VE.getValueID(C->getOperand(1)));
-        Record.push_back(VE.getValueID(C->getOperand(2)));
+        Record.push_back(VE.getValueID(CE->getShuffleMaskForBitcode()));
         break;
       case Instruction::ICmp:
       case Instruction::FCmp:
@@ -2702,7 +2702,8 @@
     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
     pushValueAndType(I.getOperand(0), InstID, Vals);
     pushValue(I.getOperand(1), InstID, Vals);
-    pushValue(I.getOperand(2), InstID, Vals);
+    pushValue(cast<ShuffleVectorInst>(I).getShuffleMaskForBitcode(), InstID,
+              Vals);
     break;
   case Instruction::ICmp:
   case Instruction::FCmp: {
diff --git a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
--- a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -88,11 +88,16 @@
   if (OM.lookup(V).first)
     return;
 
-  if (const Constant *C = dyn_cast<Constant>(V))
-    if (C->getNumOperands() && !isa<GlobalValue>(C))
+  if (const Constant *C = dyn_cast<Constant>(V)) {
+    if (C->getNumOperands() && !isa<GlobalValue>(C)) {
       for (const Value *Op : C->operands())
         if (!isa<BasicBlock>(Op) && !isa<GlobalValue>(Op))
           orderValue(Op, OM);
+      if (auto *CE = dyn_cast<ConstantExpr>(C))
+        if (CE->getOpcode() == Instruction::ShuffleVector)
+          orderValue(CE->getShuffleMaskForBitcode(), OM);
+    }
+  }
 
   // Note: we cannot cache this lookup above, since inserting into the map
   // changes the map's size, and thus affects the other IDs.
@@ -155,11 +160,14 @@
     for (const Argument &A : F.args())
       orderValue(&A, OM);
     for (const BasicBlock &BB : F)
-      for (const Instruction &I : BB)
+      for (const Instruction &I : BB) {
         for (const Value *Op : I.operands())
           if ((isa<Constant>(*Op) && !isa<GlobalValue>(*Op)) ||
               isa<InlineAsm>(*Op))
             orderValue(Op, OM);
+        if (auto *SVI = dyn_cast<ShuffleVectorInst>(&I))
+          orderValue(SVI->getShuffleMaskForBitcode(), OM);
+      }
     for (const BasicBlock &BB : F)
       for (const Instruction &I : BB)
         orderValue(&I, OM);
@@ -250,11 +258,17 @@
     predictValueUseListOrderImpl(V, F, IDPair.first, OM, Stack);
 
   // Recursive descent into constants.
-  if (const Constant *C = dyn_cast<Constant>(V))
-    if (C->getNumOperands()) // Visit GlobalValues.
+  if (const Constant *C = dyn_cast<Constant>(V)) {
+    if (C->getNumOperands()) { // Visit GlobalValues.
       for (const Value *Op : C->operands())
         if (isa<Constant>(Op)) // Visit GlobalValues.
           predictValueUseListOrder(Op, F, OM, Stack);
+      if (auto *CE = dyn_cast<ConstantExpr>(C))
+        if (CE->getOpcode() == Instruction::ShuffleVector)
+          predictValueUseListOrder(CE->getShuffleMaskForBitcode(), F, OM,
+                                   Stack);
+    }
+  }
 }
 
 static UseListOrderStack predictUseListOrder(const Module &M) {
@@ -279,10 +293,14 @@
     for (const Argument &A : F.args())
       predictValueUseListOrder(&A, &F, OM, Stack);
     for (const BasicBlock &BB : F)
-      for (const Instruction &I : BB)
+      for (const Instruction &I : BB) {
         for (const Value *Op : I.operands())
           if (isa<Constant>(*Op) || isa<InlineAsm>(*Op)) // Visit GlobalValues.
             predictValueUseListOrder(Op, &F, OM, Stack);
+        if (auto *SVI = dyn_cast<ShuffleVectorInst>(&I))
+          predictValueUseListOrder(SVI->getShuffleMaskForBitcode(), &F, OM,
+                                   Stack);
+      }
     for (const BasicBlock &BB : F)
       for (const Instruction &I : BB)
         predictValueUseListOrder(&I, &F, OM, Stack);
@@ -413,6 +431,8 @@
 
           EnumerateMetadata(&F, MD->getMetadata());
         }
+        if (auto *SVI = dyn_cast<ShuffleVectorInst>(&I))
+          EnumerateType(SVI->getShuffleMaskForBitcode()->getType());
         EnumerateType(I.getType());
         if (const auto *Call = dyn_cast<CallBase>(&I))
           EnumerateAttributes(Call->getAttributes());
@@ -836,6 +856,9 @@
            I != E; ++I)
         if (!isa<BasicBlock>(*I)) // Don't enumerate BB operand to BlockAddress.
           EnumerateValue(*I);
+      if (auto *CE = dyn_cast<ConstantExpr>(C))
+        if (CE->getOpcode() == Instruction::ShuffleVector)
+          EnumerateValue(CE->getShuffleMaskForBitcode());
 
       // Finally, add the value.  Doing this could make the ValueID reference be
       // dangling, don't reuse it.
@@ -913,6 +936,9 @@
 
     EnumerateOperandType(Op);
   }
+  if (auto *CE = dyn_cast<ConstantExpr>(C))
+    if (CE->getOpcode() == Instruction::ShuffleVector)
+      EnumerateOperandType(CE->getShuffleMaskForBitcode());
 }
 
 void ValueEnumerator::EnumerateAttributes(AttributeList PAL) {
@@ -958,11 +984,14 @@
 
   // Add all function-level constants to the value table.
   for (const BasicBlock &BB : F) {
-    for (const Instruction &I : BB)
+    for (const Instruction &I : BB) {
       for (const Use &OI : I.operands()) {
         if ((isa<Constant>(OI) && !isa<GlobalValue>(OI)) || isa<InlineAsm>(OI))
           EnumerateValue(OI);
       }
+      if (auto *SVI = dyn_cast<ShuffleVectorInst>(&I))
+        EnumerateValue(SVI->getShuffleMaskForBitcode());
+    }
     BasicBlocks.push_back(&BB);
     ValueMap[&BB] = BasicBlocks.size();
   }
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -6257,7 +6257,7 @@
 }
 
 static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {
-  SmallVector<int, 16> Mask(SVI->getShuffleMask());
+  ArrayRef<int> Mask(SVI->getShuffleMask());
   int SplatElem = -1;
   for (unsigned i = 0; i < Mask.size(); ++i) {
     if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)
@@ -6307,7 +6307,7 @@
       assert(InsertPt != UserBB->end());
       InsertedShuffle =
           new ShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
-                                SVI->getOperand(2), "", &*InsertPt);
+                                SVI->getShuffleMask(), "", &*InsertPt);
       InsertedShuffle->setDebugLoc(SVI->getDebugLoc());
     }
 
diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -1973,8 +1973,11 @@
 
 bool IRTranslator::translateShuffleVector(const User &U,
                                           MachineIRBuilder &MIRBuilder) {
-  SmallVector<int, 8> Mask;
-  ShuffleVectorInst::getShuffleMask(cast<Constant>(U.getOperand(2)), Mask);
+  ArrayRef<int> Mask;
+  if (auto *SVI = dyn_cast<ShuffleVectorInst>(&U))
+    Mask = SVI->getShuffleMask();
+  else
+    Mask = cast<ConstantExpr>(U).getShuffleMask();
   ArrayRef<int> MaskAlloc = MF->allocateShuffleMask(Mask);
   MIRBuilder
       .buildInstr(TargetOpcode::G_SHUFFLE_VECTOR, {getOrCreateVReg(U)},
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3437,14 +3437,19 @@
 void SelectionDAGBuilder::visitShuffleVector(const User &I) {
   SDValue Src1 = getValue(I.getOperand(0));
   SDValue Src2 = getValue(I.getOperand(1));
-  Constant *MaskV = cast<Constant>(I.getOperand(2));
+  ArrayRef<int> Mask;
+  if (auto *SVI = dyn_cast<ShuffleVectorInst>(&I))
+    Mask = SVI->getShuffleMask();
+  else
+    Mask = cast<ConstantExpr>(I).getShuffleMask();
   SDLoc DL = getCurSDLoc();
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
   EVT VT = TLI.getValueType(DAG.getDataLayout(), I.getType());
   EVT SrcVT = Src1.getValueType();
   unsigned SrcNumElts = SrcVT.getVectorNumElements();
 
-  if (MaskV->isNullValue() && VT.isScalableVector()) {
+  if (all_of(Mask, [](int Elem) { return Elem == 0; }) &&
+      VT.isScalableVector()) {
     // Canonical splat form of first element of first input vector.
     SDValue FirstElt =
         DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, SrcVT.getScalarType(), Src1,
@@ -3458,8 +3463,6 @@
   // for targets that support a SPLAT_VECTOR for non-scalable vector types.
   assert(!VT.isScalableVector() && "Unsupported scalable vector shuffle");
 
-  SmallVector<int, 8> Mask;
-  ShuffleVectorInst::getShuffleMask(MaskV, Mask);
   unsigned MaskNumElts = Mask.size();
 
   if (SrcNumElts == MaskNumElts) {
diff --git a/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp b/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp
--- a/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp
+++ b/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp
@@ -1868,7 +1868,6 @@
 
   GenericValue Src1 = getOperandValue(I.getOperand(0), SF);
   GenericValue Src2 = getOperandValue(I.getOperand(1), SF);
-  GenericValue Src3 = getOperandValue(I.getOperand(2), SF);
   GenericValue Dest;
 
   // There is no need to check types of src1 and src2, because the compiled
@@ -1878,7 +1877,7 @@
   Type *TyContained = Ty->getElementType();
   unsigned src1Size = (unsigned)Src1.AggregateVal.size();
   unsigned src2Size = (unsigned)Src2.AggregateVal.size();
-  unsigned src3Size = (unsigned)Src3.AggregateVal.size();
+  unsigned src3Size = I.getShuffleMask().size();
 
   Dest.AggregateVal.resize(src3Size);
 
@@ -1888,7 +1887,7 @@
       break;
     case Type::IntegerTyID:
       for( unsigned i=0; i<src3Size; i++) {
-        unsigned j = Src3.AggregateVal[i].IntVal.getZExtValue();
+        unsigned j = std::max(0, I.getMaskValue(i));
         if(j < src1Size)
           Dest.AggregateVal[i].IntVal = Src1.AggregateVal[j].IntVal;
         else if(j < src1Size + src2Size)
@@ -1904,7 +1903,7 @@
       break;
     case Type::FloatTyID:
       for( unsigned i=0; i<src3Size; i++) {
-        unsigned j = Src3.AggregateVal[i].IntVal.getZExtValue();
+        unsigned j = std::max(0, I.getMaskValue(i));
         if(j < src1Size)
           Dest.AggregateVal[i].FloatVal = Src1.AggregateVal[j].FloatVal;
         else if(j < src1Size + src2Size)
@@ -1915,7 +1914,7 @@
       break;
     case Type::DoubleTyID:
       for( unsigned i=0; i<src3Size; i++) {
-        unsigned j = Src3.AggregateVal[i].IntVal.getZExtValue();
+        unsigned j = std::max(0, I.getMaskValue(i));
         if(j < src1Size)
           Dest.AggregateVal[i].DoubleVal = Src1.AggregateVal[j].DoubleVal;
         else if(j < src1Size + src2Size)
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -462,6 +462,33 @@
                 isa<GlobalValue>(V) ? GlobalPrefix : LocalPrefix);
 }
 
+static void PrintShuffleMask(raw_ostream &Out, Type *Ty, ArrayRef<int> Mask) {
+  Out << ", <";
+  if (Ty->getVectorIsScalable())
+    Out << "vscale x ";
+  Out << Mask.size() << " x i32> ";
+  bool FirstElt = true;
+  if (all_of(Mask, [](int Elt) { return Elt == 0; })) {
+    Out << "zeroinitializer";
+  } else if (all_of(Mask, [](int Elt) { return Elt == UndefMaskElem; })) {
+    Out << "undef";
+  } else {
+    Out << "<";
+    for (int Elt : Mask) {
+      if (FirstElt)
+        FirstElt = false;
+      else
+        Out << ", ";
+      Out << "i32 ";
+      if (Elt == UndefMaskElem)
+        Out << "undef";
+      else
+        Out << Elt;
+    }
+    Out << ">";
+  }
+}
+
 namespace {
 
 class TypePrinting {
@@ -1547,6 +1574,9 @@
       TypePrinter.print(CE->getType(), Out);
     }
 
+    if (CE->getOpcode() == Instruction::ShuffleVector)
+      PrintShuffleMask(Out, CE->getType(), CE->getShuffleMask());
+
     Out << ')';
     return;
   }
@@ -4093,6 +4123,8 @@
                 RMWI->getSyncScopeID());
   } else if (const FenceInst *FI = dyn_cast<FenceInst>(&I)) {
     writeAtomic(FI->getContext(), FI->getOrdering(), FI->getSyncScopeID());
+  } else if (const ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(&I)) {
+    PrintShuffleMask(Out, SVI->getType(), SVI->getShuffleMask());
   }
 
   // Print Metadata info.
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -2335,11 +2335,12 @@
                                             PointerType::getUnqual(VT));
       Value *Load = Builder.CreateAlignedLoad(VT, Op, Align(1));
       if (NumSrcElts == 2)
-        Rep = Builder.CreateShuffleVector(Load, UndefValue::get(Load->getType()),
-                                          { 0, 1, 0, 1 });
+        Rep = Builder.CreateShuffleVector(
+            Load, UndefValue::get(Load->getType()), ArrayRef<int>{0, 1, 0, 1});
       else
-        Rep = Builder.CreateShuffleVector(Load, UndefValue::get(Load->getType()),
-                                          { 0, 1, 2, 3, 0, 1, 2, 3 });
+        Rep =
+            Builder.CreateShuffleVector(Load, UndefValue::get(Load->getType()),
+                                        ArrayRef<int>{0, 1, 2, 3, 0, 1, 2, 3});
     } else if (IsX86 && (Name.startswith("avx512.mask.shuf.i") ||
                          Name.startswith("avx512.mask.shuf.f"))) {
       unsigned Imm = cast<ConstantInt>(CI->getArgOperand(2))->getZExtValue();
diff --git a/llvm/lib/IR/ConstantFold.h b/llvm/lib/IR/ConstantFold.h
--- a/llvm/lib/IR/ConstantFold.h
+++ b/llvm/lib/IR/ConstantFold.h
@@ -38,7 +38,7 @@
   Constant *ConstantFoldInsertElementInstruction(Constant *Val, Constant *Elt,
                                                  Constant *Idx);
   Constant *ConstantFoldShuffleVectorInstruction(Constant *V1, Constant *V2,
-                                                 Constant *Mask);
+                                                 ArrayRef<int> Mask);
   Constant *ConstantFoldExtractValueInstruction(Constant *Agg,
                                                 ArrayRef<unsigned> Idxs);
   Constant *ConstantFoldInsertValueInstruction(Constant *Agg, Constant *Val,
diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/lib/IR/ConstantFold.cpp
@@ -876,22 +876,22 @@
   return ConstantVector::get(Result);
 }
 
-Constant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1,
-                                                     Constant *V2,
-                                                     Constant *Mask) {
-  ElementCount MaskEltCount = Mask->getType()->getVectorElementCount();
+Constant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1, Constant *V2,
+                                                     ArrayRef<int> Mask) {
+  unsigned MaskNumElts = Mask.size();
+  ElementCount MaskEltCount = {MaskNumElts,
+                               V1->getType()->getVectorIsScalable()};
   Type *EltTy = V1->getType()->getVectorElementType();
 
   // Undefined shuffle mask -> undefined value.
-  if (isa<UndefValue>(Mask))
-    return UndefValue::get(VectorType::get(EltTy, MaskEltCount));
-
-  // Don't break the bitcode reader hack.
-  if (isa<ConstantExpr>(Mask)) return nullptr;
+  if (all_of(Mask, [](int Elt) { return Elt == UndefMaskElem; })) {
+    return UndefValue::get(VectorType::get(EltTy, MaskNumElts));
+  }
 
   // If the mask is all zeros this is a splat, no need to go through all
   // elements.
-  if (isa<ConstantAggregateZero>(Mask) && !MaskEltCount.Scalable) {
+  if (all_of(Mask, [](int Elt) { return Elt == 0; }) &&
+      !MaskEltCount.Scalable) {
     Type *Ty = IntegerType::get(V1->getContext(), 32);
     Constant *Elt =
         ConstantExpr::getExtractElement(V1, ConstantInt::get(Ty, 0));
@@ -903,13 +903,12 @@
   if (ValTy->isScalable())
     return nullptr;
 
-  unsigned MaskNumElts = MaskEltCount.Min;
   unsigned SrcNumElts = V1->getType()->getVectorNumElements();
 
   // Loop over the shuffle mask, evaluating each element.
   SmallVector<Constant*, 32> Result;
   for (unsigned i = 0; i != MaskNumElts; ++i) {
-    int Elt = ShuffleVectorInst::getMaskValue(Mask, i);
+    int Elt = Mask[i];
     if (Elt == -1) {
       Result.push_back(UndefValue::get(EltTy));
       continue;
diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -1230,8 +1230,7 @@
   Constant *UndefV = UndefValue::get(VTy);
   V = ConstantExpr::getInsertElement(UndefV, V, ConstantInt::get(I32Ty, 0));
   // Build shuffle mask to perform the splat.
-  Type *MaskTy = VectorType::get(I32Ty, EC);
-  Constant *Zeros = ConstantAggregateZero::get(MaskTy);
+  SmallVector<int, 8> Zeros(EC.Min, 0);
   // Splat.
   return ConstantExpr::getShuffleVector(V, UndefV, Zeros);
 }
@@ -1298,6 +1297,14 @@
   return cast<CompareConstantExpr>(this)->predicate;
 }
 
+ArrayRef<int> ConstantExpr::getShuffleMask() const {
+  return cast<ShuffleVectorConstantExpr>(this)->ShuffleMask;
+}
+
+Constant *ConstantExpr::getShuffleMaskForBitcode() const {
+  return cast<ShuffleVectorConstantExpr>(this)->ShuffleMaskForBitcode;
+}
+
 Constant *
 ConstantExpr::getWithOperandReplaced(unsigned OpNo, Constant *Op) const {
   assert(Op->getType() == getOperand(OpNo)->getType() &&
@@ -1349,7 +1356,7 @@
   case Instruction::ExtractValue:
     return ConstantExpr::getExtractValue(Ops[0], getIndices(), OnlyIfReducedTy);
   case Instruction::ShuffleVector:
-    return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2],
+    return ConstantExpr::getShuffleVector(Ops[0], Ops[1], getShuffleMask(),
                                           OnlyIfReducedTy);
   case Instruction::GetElementPtr: {
     auto *GEPO = cast<GEPOperator>(this);
@@ -2152,7 +2159,7 @@
   if (InRangeIndex && *InRangeIndex < 63)
     SubClassOptionalData |= (*InRangeIndex + 1) << 1;
   const ConstantExprKeyType Key(Instruction::GetElementPtr, ArgVec, 0,
-                                SubClassOptionalData, None, Ty);
+                                SubClassOptionalData, None, None, Ty);
 
   LLVMContextImpl *pImpl = C->getContext().pImpl;
   return pImpl->ExprConstants.getOrCreate(ReqTy, Key);
@@ -2254,23 +2261,25 @@
 }
 
 Constant *ConstantExpr::getShuffleVector(Constant *V1, Constant *V2,
-                                         Constant *Mask, Type *OnlyIfReducedTy) {
+                                         ArrayRef<int> Mask,
+                                         Type *OnlyIfReducedTy) {
   assert(ShuffleVectorInst::isValidOperands(V1, V2, Mask) &&
          "Invalid shuffle vector constant expr operands!");
 
   if (Constant *FC = ConstantFoldShuffleVectorInstruction(V1, V2, Mask))
     return FC;          // Fold a few common cases.
 
-  ElementCount NElts = Mask->getType()->getVectorElementCount();
+  unsigned NElts = Mask.size();
   Type *EltTy = V1->getType()->getVectorElementType();
-  Type *ShufTy = VectorType::get(EltTy, NElts);
+  bool TypeIsScalable = V1->getType()->getVectorIsScalable();
+  Type *ShufTy = VectorType::get(EltTy, NElts, TypeIsScalable);
 
   if (OnlyIfReducedTy == ShufTy)
     return nullptr;
 
   // Look up the constant in the table first to ensure uniqueness
-  Constant *ArgVec[] = { V1, V2, Mask };
-  const ConstantExprKeyType Key(Instruction::ShuffleVector, ArgVec);
+  Constant *ArgVec[] = {V1, V2};
+  ConstantExprKeyType Key(Instruction::ShuffleVector, ArgVec, 0, 0, None, Mask);
 
   LLVMContextImpl *pImpl = ShufTy->getContext().pImpl;
   return pImpl->ExprConstants.getOrCreate(ShufTy, Key);
@@ -3117,7 +3126,7 @@
   case Instruction::ExtractValue:
     return ExtractValueInst::Create(Ops[0], getIndices());
   case Instruction::ShuffleVector:
-    return new ShuffleVectorInst(Ops[0], Ops[1], Ops[2]);
+    return new ShuffleVectorInst(Ops[0], Ops[1], getShuffleMask());
 
   case Instruction::GetElementPtr: {
     const auto *GO = cast<GEPOperator>(this);
diff --git a/llvm/lib/IR/ConstantsContext.h b/llvm/lib/IR/ConstantsContext.h
--- a/llvm/lib/IR/ConstantsContext.h
+++ b/llvm/lib/IR/ConstantsContext.h
@@ -26,6 +26,7 @@
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
 #include "llvm/IR/OperandTraits.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Debug.h"
@@ -146,21 +147,24 @@
 /// shufflevector constant exprs.
 class ShuffleVectorConstantExpr : public ConstantExpr {
 public:
-  ShuffleVectorConstantExpr(Constant *C1, Constant *C2, Constant *C3)
-  : ConstantExpr(VectorType::get(
-                   cast<VectorType>(C1->getType())->getElementType(),
-                   cast<VectorType>(C3->getType())->getElementCount()),
-                 Instruction::ShuffleVector,
-                 &Op<0>(), 3) {
+  ShuffleVectorConstantExpr(Constant *C1, Constant *C2, ArrayRef<int> Mask)
+      : ConstantExpr(
+            VectorType::get(cast<VectorType>(C1->getType())->getElementType(),
+                            Mask.size(), C1->getType()->getVectorIsScalable()),
+            Instruction::ShuffleVector, &Op<0>(), 2) {
+    assert(ShuffleVectorInst::isValidOperands(C1, C2, Mask) &&
+           "Invalid shuffle vector instruction operands!");
     Op<0>() = C1;
     Op<1>() = C2;
-    Op<2>() = C3;
+    ShuffleMask.assign(Mask.begin(), Mask.end());
+    ShuffleMaskForBitcode =
+        ShuffleVectorInst::convertShuffleMaskForBitcode(Mask, getType());
   }
 
-  // allocate space for exactly three operands
-  void *operator new(size_t s) {
-    return User::operator new(s, 3);
-  }
+  SmallVector<int, 4> ShuffleMask;
+  Constant *ShuffleMaskForBitcode;
+
+  void *operator new(size_t s) { return User::operator new(s, 2); }
 
   /// Transparently provide more efficient getOperand methods.
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
@@ -319,7 +323,7 @@
 
 template <>
 struct OperandTraits<ShuffleVectorConstantExpr>
-    : public FixedNumOperandTraits<ShuffleVectorConstantExpr, 3> {};
+    : public FixedNumOperandTraits<ShuffleVectorConstantExpr, 2> {};
 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ShuffleVectorConstantExpr, Value)
 
 template <>
@@ -460,36 +464,58 @@
 };
 
 struct ConstantExprKeyType {
+private:
   uint8_t Opcode;
   uint8_t SubclassOptionalData;
   uint16_t SubclassData;
   ArrayRef<Constant *> Ops;
   ArrayRef<unsigned> Indexes;
+  ArrayRef<int> ShuffleMask;
   Type *ExplicitTy;
 
+  static ArrayRef<int> getShuffleMaskIfValid(const ConstantExpr *CE) {
+    if (CE->getOpcode() == Instruction::ShuffleVector)
+      return CE->getShuffleMask();
+    return None;
+  }
+
+  static ArrayRef<unsigned> getIndicesIfValid(const ConstantExpr *CE) {
+    if (CE->hasIndices())
+      return CE->getIndices();
+    return None;
+  }
+
+  static Type *getSourceElementTypeIfValid(const ConstantExpr *CE) {
+    if (auto *GEPCE = dyn_cast<GetElementPtrConstantExpr>(CE))
+      return GEPCE->getSourceElementType();
+    return nullptr;
+  }
+
+public:
   ConstantExprKeyType(unsigned Opcode, ArrayRef<Constant *> Ops,
                       unsigned short SubclassData = 0,
                       unsigned short SubclassOptionalData = 0,
                       ArrayRef<unsigned> Indexes = None,
+                      ArrayRef<int> ShuffleMask = None,
                       Type *ExplicitTy = nullptr)
       : Opcode(Opcode), SubclassOptionalData(SubclassOptionalData),
         SubclassData(SubclassData), Ops(Ops), Indexes(Indexes),
-        ExplicitTy(ExplicitTy) {}
+        ShuffleMask(ShuffleMask), ExplicitTy(ExplicitTy) {}
 
   ConstantExprKeyType(ArrayRef<Constant *> Operands, const ConstantExpr *CE)
       : Opcode(CE->getOpcode()),
         SubclassOptionalData(CE->getRawSubclassOptionalData()),
         SubclassData(CE->isCompare() ? CE->getPredicate() : 0), Ops(Operands),
-        Indexes(CE->hasIndices() ? CE->getIndices() : ArrayRef<unsigned>()),
-        ExplicitTy(nullptr) {}
+        Indexes(getIndicesIfValid(CE)), ShuffleMask(getShuffleMaskIfValid(CE)),
+        ExplicitTy(getSourceElementTypeIfValid(CE)) {}
 
   ConstantExprKeyType(const ConstantExpr *CE,
                       SmallVectorImpl<Constant *> &Storage)
       : Opcode(CE->getOpcode()),
         SubclassOptionalData(CE->getRawSubclassOptionalData()),
         SubclassData(CE->isCompare() ? CE->getPredicate() : 0),
-        Indexes(CE->hasIndices() ? CE->getIndices() : ArrayRef<unsigned>()),
-        ExplicitTy(nullptr) {
+        Indexes(getIndicesIfValid(CE)), ShuffleMask(getShuffleMaskIfValid(CE)),
+        ExplicitTy(getSourceElementTypeIfValid(CE)) {
     assert(Storage.empty() && "Expected empty storage");
     for (unsigned I = 0, E = CE->getNumOperands(); I != E; ++I)
       Storage.push_back(CE->getOperand(I));
@@ -499,7 +525,8 @@
   bool operator==(const ConstantExprKeyType &X) const {
     return Opcode == X.Opcode && SubclassData == X.SubclassData &&
            SubclassOptionalData == X.SubclassOptionalData && Ops == X.Ops &&
-           Indexes == X.Indexes;
+           Indexes == X.Indexes && ShuffleMask == X.ShuffleMask &&
+           ExplicitTy == X.ExplicitTy;
   }
 
   bool operator==(const ConstantExpr *CE) const {
@@ -514,15 +541,21 @@
     for (unsigned I = 0, E = Ops.size(); I != E; ++I)
       if (Ops[I] != CE->getOperand(I))
         return false;
-    if (Indexes != (CE->hasIndices() ? CE->getIndices() : ArrayRef<unsigned>()))
+    if (Indexes != getIndicesIfValid(CE))
+      return false;
+    if (ShuffleMask != getShuffleMaskIfValid(CE))
+      return false;
+    if (ExplicitTy != getSourceElementTypeIfValid(CE))
       return false;
     return true;
   }
 
   unsigned getHash() const {
-    return hash_combine(Opcode, SubclassOptionalData, SubclassData,
-                        hash_combine_range(Ops.begin(), Ops.end()),
-                        hash_combine_range(Indexes.begin(), Indexes.end()));
+    return hash_combine(
+        Opcode, SubclassOptionalData, SubclassData,
+        hash_combine_range(Ops.begin(), Ops.end()),
+        hash_combine_range(Indexes.begin(), Indexes.end()),
+        hash_combine_range(ShuffleMask.begin(), ShuffleMask.end()), ExplicitTy);
   }
 
   using TypeClass = ConstantInfo<ConstantExpr>::TypeClass;
@@ -546,17 +579,14 @@
     case Instruction::InsertElement:
       return new InsertElementConstantExpr(Ops[0], Ops[1], Ops[2]);
     case Instruction::ShuffleVector:
-      return new ShuffleVectorConstantExpr(Ops[0], Ops[1], Ops[2]);
+      return new ShuffleVectorConstantExpr(Ops[0], Ops[1], ShuffleMask);
     case Instruction::InsertValue:
       return new InsertValueConstantExpr(Ops[0], Ops[1], Indexes, Ty);
     case Instruction::ExtractValue:
       return new ExtractValueConstantExpr(Ops[0], Indexes, Ty);
     case Instruction::GetElementPtr:
-      return GetElementPtrConstantExpr::Create(
-          ExplicitTy ? ExplicitTy
-                     : cast<PointerType>(Ops[0]->getType()->getScalarType())
-                           ->getElementType(),
-          Ops[0], Ops.slice(1), Ty, SubclassOptionalData);
+      return GetElementPtrConstantExpr::Create(ExplicitTy, Ops[0], Ops.slice(1),
+                                               Ty, SubclassOptionalData);
     case Instruction::ICmp:
       return new CompareConstantExpr(Ty, Instruction::ICmp, SubclassData,
                                      Ops[0], Ops[1]);
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -1781,9 +1781,11 @@
 LLVMValueRef LLVMConstShuffleVector(LLVMValueRef VectorAConstant,
                                     LLVMValueRef VectorBConstant,
                                     LLVMValueRef MaskConstant) {
+  SmallVector<int, 16> IntMask;
+  ShuffleVectorInst::getShuffleMask(unwrap<Constant>(MaskConstant), IntMask);
   return wrap(ConstantExpr::getShuffleVector(unwrap<Constant>(VectorAConstant),
                                              unwrap<Constant>(VectorBConstant),
-                                             unwrap<Constant>(MaskConstant)));
+                                             IntMask));
 }
 
 LLVMValueRef LLVMConstExtractValue(LLVMValueRef AggConstant, unsigned *IdxList,
diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -443,6 +443,9 @@
            RMWI->isVolatile() == cast<AtomicRMWInst>(I2)->isVolatile() &&
            RMWI->getOrdering() == cast<AtomicRMWInst>(I2)->getOrdering() &&
            RMWI->getSyncScopeID() == cast<AtomicRMWInst>(I2)->getSyncScopeID();
+  if (const ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I1))
+    return SVI->getShuffleMask() ==
+           cast<ShuffleVectorInst>(I2)->getShuffleMask();
 
   return true;
 }
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
@@ -1843,58 +1843,110 @@
 ShuffleVectorInst::ShuffleVectorInst(Value *V1, Value *V2, Value *Mask,
                                      const Twine &Name,
                                      Instruction *InsertBefore)
-: Instruction(VectorType::get(cast<VectorType>(V1->getType())->getElementType(),
-                cast<VectorType>(Mask->getType())->getElementCount()),
-              ShuffleVector,
-              OperandTraits<ShuffleVectorInst>::op_begin(this),
-              OperandTraits<ShuffleVectorInst>::operands(this),
-              InsertBefore) {
+    : Instruction(
+          VectorType::get(cast<VectorType>(V1->getType())->getElementType(),
+                          cast<VectorType>(Mask->getType())->getElementCount()),
+          ShuffleVector, OperandTraits<ShuffleVectorInst>::op_begin(this),
+          OperandTraits<ShuffleVectorInst>::operands(this), InsertBefore) {
   assert(isValidOperands(V1, V2, Mask) &&
          "Invalid shuffle vector instruction operands!");
+
   Op<0>() = V1;
   Op<1>() = V2;
-  Op<2>() = Mask;
+  SmallVector<int, 16> MaskArr;
+  getShuffleMask(cast<Constant>(Mask), MaskArr);
+  setShuffleMask(MaskArr);
   setName(Name);
 }
 
 ShuffleVectorInst::ShuffleVectorInst(Value *V1, Value *V2, Value *Mask,
+                                     const Twine &Name, BasicBlock *InsertAtEnd)
+    : Instruction(
+          VectorType::get(cast<VectorType>(V1->getType())->getElementType(),
+                          cast<VectorType>(Mask->getType())->getElementCount()),
+          ShuffleVector, OperandTraits<ShuffleVectorInst>::op_begin(this),
+          OperandTraits<ShuffleVectorInst>::operands(this), InsertAtEnd) {
+  assert(isValidOperands(V1, V2, Mask) &&
+         "Invalid shuffle vector instruction operands!");
+
+  Op<0>() = V1;
+  Op<1>() = V2;
+  SmallVector<int, 16> MaskArr;
+  getShuffleMask(cast<Constant>(Mask), MaskArr);
+  setShuffleMask(MaskArr);
+  setName(Name);
+}
+
+ShuffleVectorInst::ShuffleVectorInst(Value *V1, Value *V2, ArrayRef<int> Mask,
                                      const Twine &Name,
-                                     BasicBlock *InsertAtEnd)
-: Instruction(VectorType::get(cast<VectorType>(V1->getType())->getElementType(),
-                cast<VectorType>(Mask->getType())->getElementCount()),
-              ShuffleVector,
-              OperandTraits<ShuffleVectorInst>::op_begin(this),
-              OperandTraits<ShuffleVectorInst>::operands(this),
-              InsertAtEnd) {
+                                     Instruction *InsertBefore)
+    : Instruction(
+          VectorType::get(cast<VectorType>(V1->getType())->getElementType(),
+                          Mask.size(), V1->getType()->getVectorIsScalable()),
+          ShuffleVector, OperandTraits<ShuffleVectorInst>::op_begin(this),
+          OperandTraits<ShuffleVectorInst>::operands(this), InsertBefore) {
+  assert(isValidOperands(V1, V2, Mask) &&
+         "Invalid shuffle vector instruction operands!");
+  Op<0>() = V1;
+  Op<1>() = V2;
+  setShuffleMask(Mask);
+  setName(Name);
+}
+
+ShuffleVectorInst::ShuffleVectorInst(Value *V1, Value *V2, ArrayRef<int> Mask,
+                                     const Twine &Name, BasicBlock *InsertAtEnd)
+    : Instruction(
+          VectorType::get(cast<VectorType>(V1->getType())->getElementType(),
+                          Mask.size(), V1->getType()->getVectorIsScalable()),
+          ShuffleVector, OperandTraits<ShuffleVectorInst>::op_begin(this),
+          OperandTraits<ShuffleVectorInst>::operands(this), InsertAtEnd) {
   assert(isValidOperands(V1, V2, Mask) &&
          "Invalid shuffle vector instruction operands!");
 
   Op<0>() = V1;
   Op<1>() = V2;
-  Op<2>() = Mask;
+  setShuffleMask(Mask);
   setName(Name);
 }
 
 void ShuffleVectorInst::commute() {
   int NumOpElts = Op<0>()->getType()->getVectorNumElements();
-  int NumMaskElts = getMask()->getType()->getVectorNumElements();
-  SmallVector<Constant*, 16> NewMask(NumMaskElts);
-  Type *Int32Ty = Type::getInt32Ty(getContext());
+  int NumMaskElts = ShuffleMask.size();
+  SmallVector<int, 16> NewMask(NumMaskElts);
   for (int i = 0; i != NumMaskElts; ++i) {
     int MaskElt = getMaskValue(i);
-    if (MaskElt == -1) {
-      NewMask[i] = UndefValue::get(Int32Ty);
+    if (MaskElt == UndefMaskElem) {
+      NewMask[i] = UndefMaskElem;
       continue;
     }
     assert(MaskElt >= 0 && MaskElt < 2 * NumOpElts && "Out-of-range mask");
     MaskElt = (MaskElt < NumOpElts) ? MaskElt + NumOpElts : MaskElt - NumOpElts;
-    NewMask[i] = ConstantInt::get(Int32Ty, MaskElt);
+    NewMask[i] = MaskElt;
   }
-  Op<2>() = ConstantVector::get(NewMask);
+  setShuffleMask(NewMask);
   Op<0>().swap(Op<1>());
 }
 
 bool ShuffleVectorInst::isValidOperands(const Value *V1, const Value *V2,
+                                        ArrayRef<int> Mask) {
+  // V1 and V2 must be vectors of the same type.
+  if (!V1->getType()->isVectorTy() || V1->getType() != V2->getType())
+    return false;
+
+  // Make sure the mask elements make sense.
+  int V1Size = cast<VectorType>(V1->getType())->getNumElements();
+  for (int Elem : Mask)
+    if (Elem != UndefMaskElem && Elem >= V1Size * 2)
+      return false;
+
+  if (V1->getType()->getVectorIsScalable())
+    if ((Mask[0] != 0 && Mask[0] != UndefMaskElem) || !is_splat(Mask))
+      return false;
+
+  return true;
+}
+
+bool ShuffleVectorInst::isValidOperands(const Value *V1, const Value *V2,
                                         const Value *Mask) {
   // V1 and V2 must be vectors of the same type.
   if (!V1->getType()->isVectorTy() || V1->getType() != V2->getType())
@@ -1902,7 +1954,8 @@
 
   // Mask must be vector of i32.
   auto *MaskTy = dyn_cast<VectorType>(Mask->getType());
-  if (!MaskTy || !MaskTy->getElementType()->isIntegerTy(32))
+  if (!MaskTy || !MaskTy->getElementType()->isIntegerTy(32) ||
+      MaskTy->isScalable() != V1->getType()->getVectorIsScalable())
     return false;
 
   // Check to see if Mask is valid.
@@ -1930,34 +1983,12 @@
     return true;
   }
 
-  // The bitcode reader can create a place holder for a forward reference
-  // used as the shuffle mask. When this occurs, the shuffle mask will
-  // fall into this case and fail. To avoid this error, do this bit of
-  // ugliness to allow such a mask pass.
-  if (const auto *CE = dyn_cast<ConstantExpr>(Mask))
-    if (CE->getOpcode() == Instruction::UserOp1)
-      return true;
-
   return false;
 }
 
-int ShuffleVectorInst::getMaskValue(const Constant *Mask, unsigned i) {
-  assert(i < Mask->getType()->getVectorNumElements() && "Index out of range");
-  assert(!Mask->getType()->getVectorElementCount().Scalable &&
-    "Length of scalable vectors unknown at compile time");
-  if (auto *CDS = dyn_cast<ConstantDataSequential>(Mask))
-    return CDS->getElementAsInteger(i);
-  Constant *C = Mask->getAggregateElement(i);
-  if (isa<UndefValue>(C))
-    return -1;
-  return cast<ConstantInt>(C)->getZExtValue();
-}
-
 void ShuffleVectorInst::getShuffleMask(const Constant *Mask,
                                        SmallVectorImpl<int> &Result) {
-  assert(!Mask->getType()->getVectorElementCount().Scalable &&
-    "Length of scalable vectors unknown at compile time");
-  unsigned NumElts = Mask->getType()->getVectorNumElements();
+  unsigned NumElts = Mask->getType()->getVectorElementCount().Min;
   if (isa<ConstantAggregateZero>(Mask)) {
     Result.resize(NumElts, 0);
     return;
@@ -1975,6 +2006,30 @@
   }
 }
 
+void ShuffleVectorInst::setShuffleMask(ArrayRef<int> Mask) {
+  ShuffleMask.assign(Mask.begin(), Mask.end());
+  ShuffleMaskForBitcode = convertShuffleMaskForBitcode(Mask, getType());
+}
+Constant *ShuffleVectorInst::convertShuffleMaskForBitcode(ArrayRef<int> Mask,
+                                                          Type *ResultTy) {
+  Type *Int32Ty = Type::getInt32Ty(ResultTy->getContext());
+  if (ResultTy->getVectorIsScalable()) {
+    assert(is_splat(Mask) && "Unexpected shuffle");
+    Type *VecTy = VectorType::get(Int32Ty, Mask.size(), true);
+    if (Mask[0] == 0)
+      return Constant::getNullValue(VecTy);
+    return UndefValue::get(VecTy);
+  }
+  SmallVector<Constant *, 16> MaskConst;
+  for (int Elem : Mask) {
+    if (Elem == UndefMaskElem)
+      MaskConst.push_back(UndefValue::get(Int32Ty));
+    else
+      MaskConst.push_back(ConstantInt::get(Int32Ty, Elem));
+  }
+  return ConstantVector::get(MaskConst);
+}
+
 static bool isSingleSourceMaskImpl(ArrayRef<int> Mask, int NumOpElts) {
   assert(!Mask.empty() && "Shuffle mask must contain elements");
   bool UsesLHS = false;
@@ -2124,7 +2179,7 @@
     return false;
 
   // The first part of the mask must choose elements from exactly 1 source op.
-  SmallVector<int, 16> Mask = getShuffleMask();
+  ArrayRef<int> Mask = getShuffleMask();
   if (!isIdentityMaskImpl(Mask, NumOpElts))
     return false;
 
@@ -4298,7 +4353,7 @@
 }
 
 ShuffleVectorInst *ShuffleVectorInst::cloneImpl() const {
-  return new ShuffleVectorInst(getOperand(0), getOperand(1), getOperand(2));
+  return new ShuffleVectorInst(getOperand(0), getOperand(1), getShuffleMask());
 }
 
 PHINode *PHINode::cloneImpl() const { return new PHINode(*this); }
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -3310,7 +3310,7 @@
 
 void Verifier::visitShuffleVectorInst(ShuffleVectorInst &SV) {
   Assert(ShuffleVectorInst::isValidOperands(SV.getOperand(0), SV.getOperand(1),
-                                            SV.getOperand(2)),
+                                            SV.getShuffleMask()),
          "Invalid shufflevector operands!", &SV);
   visitInstruction(SV);
 }
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -9207,10 +9207,10 @@
     return FullVT->getNumElements() == 2 * HalfVT->getNumElements();
   };
 
-  Constant *M1, *M2;
+  ArrayRef<int> M1, M2;
   Value *S1Op1, *S2Op1;
-  if (!match(Op1, m_ShuffleVector(m_Value(S1Op1), m_Undef(), m_Constant(M1))) ||
-      !match(Op2, m_ShuffleVector(m_Value(S2Op1), m_Undef(), m_Constant(M2))))
+  if (!match(Op1, m_ShuffleVector(m_Value(S1Op1), m_Undef(), m_Mask(M1))) ||
+      !match(Op2, m_ShuffleVector(m_Value(S2Op1), m_Undef(), m_Mask(M2))))
     return false;
 
   // Check that the operands are half as wide as the result and we extract
diff --git a/llvm/lib/Target/AMDGPU/AMDGPULowerKernelArguments.cpp b/llvm/lib/Target/AMDGPU/AMDGPULowerKernelArguments.cpp
--- a/llvm/lib/Target/AMDGPU/AMDGPULowerKernelArguments.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULowerKernelArguments.cpp
@@ -210,7 +210,7 @@
       Arg.replaceAllUsesWith(NewVal);
     } else if (IsV3) {
       Value *Shuf = Builder.CreateShuffleVector(Load, UndefValue::get(V4Ty),
-                                                {0, 1, 2},
+                                                ArrayRef<int>{0, 1, 2},
                                                 Arg.getName() + ".load");
       Arg.replaceAllUsesWith(Shuf);
     } else {
diff --git a/llvm/lib/Target/AMDGPU/AMDGPURewriteOutArguments.cpp b/llvm/lib/Target/AMDGPU/AMDGPURewriteOutArguments.cpp
--- a/llvm/lib/Target/AMDGPU/AMDGPURewriteOutArguments.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPURewriteOutArguments.cpp
@@ -409,7 +409,7 @@
             DL->getTypeSizeInBits(Val->getType())) {
           assert(isVec3ToVec4Shuffle(EffectiveEltTy, Val->getType()));
           Val = B.CreateShuffleVector(Val, UndefValue::get(Val->getType()),
-                                      { 0, 1, 2 });
+                                      ArrayRef<int>{0, 1, 2});
         }
 
         Val = B.CreateBitCast(Val, EffectiveEltTy);
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -15547,7 +15547,7 @@
     return false;
   if (!match(I->getOperand(Op),
              m_ShuffleVector(m_InsertElement(m_Undef(), m_Value(), m_ZeroInt()),
-                             m_Undef(), m_Zero()))) {
+                             m_Undef(), m_ZeroMask()))) {
     return false;
   }
   Instruction *Shuffle = cast<Instruction>(I->getOperand(Op));
diff --git a/llvm/lib/Target/ARM/MVETailPredication.cpp b/llvm/lib/Target/ARM/MVETailPredication.cpp
--- a/llvm/lib/Target/ARM/MVETailPredication.cpp
+++ b/llvm/lib/Target/ARM/MVETailPredication.cpp
@@ -286,7 +286,7 @@
   Instruction *Insert = nullptr;
   // The shuffle which broadcasts the index iv into a vector.
   if (!match(BroadcastSplat,
-             m_ShuffleVector(m_Instruction(Insert), m_Undef(), m_Zero())))
+             m_ShuffleVector(m_Instruction(Insert), m_Undef(), m_ZeroMask())))
     return false;
 
   // The insert element which initialises a vector with the index iv.
@@ -409,7 +409,7 @@
   Instruction *Insert = nullptr;
 
   if (!match(Shuffle,
-             m_ShuffleVector(m_Instruction(Insert), m_Undef(), m_Zero())))
+             m_ShuffleVector(m_Instruction(Insert), m_Undef(), m_ZeroMask())))
     return false;
 
   // Insert the limit into a vector.
diff --git a/llvm/lib/Target/X86/X86PartialReduction.cpp b/llvm/lib/Target/X86/X86PartialReduction.cpp
--- a/llvm/lib/Target/X86/X86PartialReduction.cpp
+++ b/llvm/lib/Target/X86/X86PartialReduction.cpp
@@ -384,7 +384,7 @@
   NumElts = OpTy->getVectorNumElements();
   if (NumElts == 2) {
     // Extract down to 2 elements.
-    Ops[0] = Builder.CreateShuffleVector(Ops[0], Ops[0], {0, 1});
+    Ops[0] = Builder.CreateShuffleVector(Ops[0], Ops[0], ArrayRef<int>{0, 1});
   } else if (NumElts >= 8) {
     SmallVector<uint32_t, 32> ConcatMask(NumElts);
     unsigned SubElts = Ops[0]->getType()->getVectorNumElements();
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -642,12 +642,12 @@
                                        InstCombiner::BuilderTy &Builder) {
   auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0));
   if (Shuf && Shuf->hasOneUse() && isa<UndefValue>(Shuf->getOperand(1)) &&
-      Shuf->getMask()->getSplatValue() &&
+      is_splat(Shuf->getShuffleMask()) &&
       Shuf->getType() == Shuf->getOperand(0)->getType()) {
     // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask
     Constant *NarrowUndef = UndefValue::get(Trunc.getType());
     Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());
-    return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getMask());
+    return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getShuffleMask());
   }
 
   return nullptr;
@@ -2553,7 +2553,7 @@
         Value *RHS = Builder.CreateBitCast(ShufOp1, DestTy);
         // Return a new shuffle vector.  Use the same element ID's, as we
         // know the vector types match #elts.
-        return new ShuffleVectorInst(LHS, RHS, Shuf->getOperand(2));
+        return new ShuffleVectorInst(LHS, RHS, Shuf->getShuffleMask());
       }
     }
 
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2814,11 +2814,10 @@
     return nullptr;
 
   Value *Vec;
-  Constant *Mask;
-  if (match(BCSrcOp,
-            m_ShuffleVector(m_Value(Vec), m_Undef(), m_Constant(Mask)))) {
+  ArrayRef<int> Mask;
+  if (match(BCSrcOp, m_ShuffleVector(m_Value(Vec), m_Undef(), m_Mask(Mask)))) {
     // Check whether every element of Mask is the same constant
-    if (auto *Elem = dyn_cast_or_null<ConstantInt>(Mask->getSplatValue())) {
+    if (is_splat(Mask)) {
       auto *VecTy = cast<VectorType>(BCSrcOp->getType());
       auto *EltTy = cast<IntegerType>(VecTy->getElementType());
       if (C->isSplat(EltTy->getBitWidth())) {
@@ -2827,6 +2826,7 @@
         // then:
         //   =>  %E = extractelement <N x iK> %vec, i32 Elem
         //       icmp <pred> iK %SplatVal, <pattern>
+        Value *Elem = Builder.getInt32(Mask[0]);
         Value *Extract = Builder.CreateExtractElement(Vec, Elem);
         Value *NewC = ConstantInt::get(EltTy, C->trunc(EltTy->getBitWidth()));
         return new ICmpInst(Pred, Extract, NewC);
@@ -5380,15 +5380,15 @@
   bool IsFP = isa<FCmpInst>(Cmp);
 
   Value *V1, *V2;
-  Constant *M;
-  if (!match(LHS, m_ShuffleVector(m_Value(V1), m_Undef(), m_Constant(M))))
+  ArrayRef<int> M;
+  if (!match(LHS, m_ShuffleVector(m_Value(V1), m_Undef(), m_Mask(M))))
     return nullptr;
 
   // If both arguments of the cmp are shuffles that use the same mask and
   // shuffle within a single vector, move the shuffle after the cmp:
   // cmp (shuffle V1, M), (shuffle V2, M) --> shuffle (cmp V1, V2), M
   Type *V1Ty = V1->getType();
-  if (match(RHS, m_ShuffleVector(m_Value(V2), m_Undef(), m_Specific(M))) &&
+  if (match(RHS, m_ShuffleVector(m_Value(V2), m_Undef(), m_SpecificMask(M))) &&
       V1Ty == V2->getType() && (LHS->hasOneUse() || RHS->hasOneUse())) {
     Value *NewCmp = IsFP ? Builder.CreateFCmp(Pred, V1, V2)
                          : Builder.CreateICmp(Pred, V1, V2);
@@ -5405,16 +5405,16 @@
   // Length-changing splats are ok, so adjust the constants as needed:
   // cmp (shuffle V1, M), C --> shuffle (cmp V1, C'), M
   Constant *ScalarC = C->getSplatValue(/* AllowUndefs */ true);
-  Constant *ScalarM = M->getSplatValue(/* AllowUndefs */ true);
-  if (ScalarC && ScalarM) {
+  int MaskSplatIndex;
+  if (ScalarC && match(M, m_SplatOrUndefMask(MaskSplatIndex))) {
     // We allow undefs in matching, but this transform removes those for safety.
     // Demanded elements analysis should be able to recover some/all of that.
     C = ConstantVector::getSplat(V1Ty->getVectorElementCount(), ScalarC);
-    M = ConstantVector::getSplat(M->getType()->getVectorElementCount(),
-                                 ScalarM);
+    SmallVector<int, 8> NewM(M.size(), MaskSplatIndex);
     Value *NewCmp = IsFP ? Builder.CreateFCmp(Pred, V1, C)
                          : Builder.CreateICmp(Pred, V1, C);
-    return new ShuffleVectorInst(NewCmp, UndefValue::get(NewCmp->getType()), M);
+    return new ShuffleVectorInst(NewCmp, UndefValue::get(NewCmp->getType()),
+                                 NewM);
   }
 
   return nullptr;
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -1389,7 +1389,7 @@
         Shuffle->getOperand(0)->getType()->getVectorNumElements();
     // Handle trivial case of a splat. Only check the first element of LHS
     // operand.
-    if (isa<ConstantAggregateZero>(Shuffle->getMask()) &&
+    if (all_of(Shuffle->getShuffleMask(), [](int Elt) { return Elt == 0; }) &&
         DemandedElts.isAllOnesValue()) {
       if (!isa<UndefValue>(I->getOperand(1))) {
         I->setOperand(1, UndefValue::get(I->getOperand(1)->getType()));
@@ -1518,15 +1518,14 @@
     }
     if (NewUndefElts) {
       // Add additional discovered undefs.
-      SmallVector<Constant*, 16> Elts;
+      SmallVector<int, 16> Elts;
       for (unsigned i = 0; i < VWidth; ++i) {
         if (UndefElts[i])
-          Elts.push_back(UndefValue::get(Type::getInt32Ty(I->getContext())));
+          Elts.push_back(UndefMaskElem);
         else
-          Elts.push_back(ConstantInt::get(Type::getInt32Ty(I->getContext()),
-                                          Shuffle->getMaskValue(i)));
+          Elts.push_back(Shuffle->getMaskValue(i));
       }
-      I->setOperand(2, ConstantVector::get(Elts));
+      Shuffle->setShuffleMask(Elts);
       MadeChange = true;
     }
     break;
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -730,7 +730,7 @@
 }
 
 static bool isShuffleEquivalentToSelect(ShuffleVectorInst &Shuf) {
-  int MaskSize = Shuf.getMask()->getType()->getVectorNumElements();
+  int MaskSize = Shuf.getShuffleMask().size();
   int VecSize = Shuf.getOperand(0)->getType()->getVectorNumElements();
 
   // A vector select does not change the size of the operands.
@@ -842,13 +842,10 @@
   // inselt (shuf (inselt undef, X, 0), undef, <0,undef,0,undef>), X, 1
   //   --> shuf (inselt undef, X, 0), undef, <0,0,0,undef>
   unsigned NumMaskElts = Shuf->getType()->getVectorNumElements();
-  SmallVector<Constant *, 16> NewMaskVec(NumMaskElts);
-  Type *I32Ty = IntegerType::getInt32Ty(Shuf->getContext());
-  Constant *Zero = ConstantInt::getNullValue(I32Ty);
+  SmallVector<int, 16> NewMask(NumMaskElts);
   for (unsigned i = 0; i != NumMaskElts; ++i)
-    NewMaskVec[i] = i == IdxC ? Zero : Shuf->getMask()->getAggregateElement(i);
+    NewMask[i] = i == IdxC ? 0 : Shuf->getMaskValue(i);
 
-  Constant *NewMask = ConstantVector::get(NewMaskVec);
   return new ShuffleVectorInst(Op0, UndefValue::get(Op0->getType()), NewMask);
 }
 
@@ -878,26 +875,23 @@
   // For example:
   // inselt (shuf X, IdMask), (extelt X, IdxC), IdxC --> shuf X, IdMask'
   unsigned NumMaskElts = Shuf->getType()->getVectorNumElements();
-  SmallVector<Constant *, 16> NewMaskVec(NumMaskElts);
-  Type *I32Ty = IntegerType::getInt32Ty(Shuf->getContext());
-  Constant *NewMaskEltC = ConstantInt::get(I32Ty, IdxC);
-  Constant *OldMask = Shuf->getMask();
+  SmallVector<int, 16> NewMask(NumMaskElts);
+  ArrayRef<int> OldMask = Shuf->getShuffleMask();
   for (unsigned i = 0; i != NumMaskElts; ++i) {
     if (i != IdxC) {
       // All mask elements besides the inserted element remain the same.
-      NewMaskVec[i] = OldMask->getAggregateElement(i);
-    } else if (OldMask->getAggregateElement(i) == NewMaskEltC) {
+      NewMask[i] = OldMask[i];
+    } else if (OldMask[i] == (int)IdxC) {
       // If the mask element was already set, there's nothing to do
       // (demanded elements analysis may unset it later).
       return nullptr;
     } else {
-      assert(isa<UndefValue>(OldMask->getAggregateElement(i)) &&
+      assert(OldMask[i] == UndefMaskElem &&
              "Unexpected shuffle mask element for identity shuffle");
-      NewMaskVec[i] = NewMaskEltC;
+      NewMask[i] = IdxC;
     }
   }
 
-  Constant *NewMask = ConstantVector::get(NewMaskVec);
   return new ShuffleVectorInst(X, Shuf->getOperand(1), NewMask);
 }
 
@@ -965,27 +959,25 @@
     // mask vector with the insertelt index plus the length of the vector
     // (because the constant vector operand of a shuffle is always the 2nd
     // operand).
-    Constant *Mask = Shuf->getMask();
-    unsigned NumElts = Mask->getType()->getVectorNumElements();
+    ArrayRef<int> Mask = Shuf->getShuffleMask();
+    unsigned NumElts = Mask.size();
     SmallVector<Constant *, 16> NewShufElts(NumElts);
-    SmallVector<Constant *, 16> NewMaskElts(NumElts);
+    SmallVector<int, 16> NewMaskElts(NumElts);
     for (unsigned I = 0; I != NumElts; ++I) {
       if (I == InsEltIndex) {
         NewShufElts[I] = InsEltScalar;
-        Type *Int32Ty = Type::getInt32Ty(Shuf->getContext());
-        NewMaskElts[I] = ConstantInt::get(Int32Ty, InsEltIndex + NumElts);
+        NewMaskElts[I] = InsEltIndex + NumElts;
       } else {
         // Copy over the existing values.
         NewShufElts[I] = ShufConstVec->getAggregateElement(I);
-        NewMaskElts[I] = Mask->getAggregateElement(I);
+        NewMaskElts[I] = Mask[I];
       }
     }
 
     // Create new operands for a shuffle that includes the constant of the
     // original insertelt. The old shuffle will be dead now.
     return new ShuffleVectorInst(Shuf->getOperand(0),
-                                 ConstantVector::get(NewShufElts),
-                                 ConstantVector::get(NewMaskElts));
+                                 ConstantVector::get(NewShufElts), NewMaskElts);
   } else if (auto *IEI = dyn_cast<InsertElementInst>(Inst)) {
     // Transform sequences of insertelements ops with constant data/indexes into
     // a single shuffle op.
@@ -1305,17 +1297,9 @@
   if (isa<ConstantAggregateZero>(V))
     return ConstantAggregateZero::get(VectorType::get(EltTy, Mask.size()));
 
-  if (Constant *C = dyn_cast<Constant>(V)) {
-    SmallVector<Constant *, 16> MaskValues;
-    for (int i = 0, e = Mask.size(); i != e; ++i) {
-      if (Mask[i] == -1)
-        MaskValues.push_back(UndefValue::get(I32Ty));
-      else
-        MaskValues.push_back(ConstantInt::get(I32Ty, Mask[i]));
-    }
+  if (Constant *C = dyn_cast<Constant>(V))
     return ConstantExpr::getShuffleVector(C, UndefValue::get(C->getType()),
-                                          ConstantVector::get(MaskValues));
-  }
+                                          Mask);
 
   Instruction *I = cast<Instruction>(V);
   switch (I->getOpcode()) {
@@ -1404,7 +1388,7 @@
 //   Shuffles to:  |EE|FF|GG|HH|
 //                 +--+--+--+--+
 static bool isShuffleExtractingFromLHS(ShuffleVectorInst &SVI,
-                                       SmallVector<int, 16> &Mask) {
+                                       ArrayRef<int> Mask) {
   unsigned LHSElems = SVI.getOperand(0)->getType()->getVectorNumElements();
   unsigned MaskElems = Mask.size();
   unsigned BegIdx = Mask.front();
@@ -1487,12 +1471,12 @@
   // Example: shuf (mul X, {-1,-2,-3,-4}), X, {0,5,6,3} --> mul X, {-1,1,1,-4}
   // Example: shuf X, (add X, {-1,-2,-3,-4}), {0,1,6,7} --> add X, {0,0,-3,-4}
   // The existing binop constant vector remains in the same operand position.
-  Constant *Mask = Shuf.getMask();
+  ArrayRef<int> Mask = Shuf.getShuffleMask();
   Constant *NewC = Op0IsBinop ? ConstantExpr::getShuffleVector(C, IdC, Mask) :
                                 ConstantExpr::getShuffleVector(IdC, C, Mask);
 
   bool MightCreatePoisonOrUB =
-      Mask->containsUndefElement() &&
+      is_contained(Mask, UndefMaskElem) &&
       (Instruction::isIntDivRem(BOpcode) || Instruction::isShift(BOpcode));
   if (MightCreatePoisonOrUB)
     NewC = getSafeVectorConstantForBinop(BOpcode, NewC, true);
@@ -1506,7 +1490,7 @@
   // An undef shuffle mask element may propagate as an undef constant element in
   // the new binop. That would produce poison where the original code might not.
   // If we already made a safe constant, then there's no danger.
-  if (Mask->containsUndefElement() && !MightCreatePoisonOrUB)
+  if (is_contained(Mask, UndefMaskElem) && !MightCreatePoisonOrUB)
     NewBO->dropPoisonGeneratingFlags();
   return NewBO;
 }
@@ -1518,14 +1502,14 @@
 static Instruction *canonicalizeInsertSplat(ShuffleVectorInst &Shuf,
                                             InstCombiner::BuilderTy &Builder) {
   Value *Op0 = Shuf.getOperand(0), *Op1 = Shuf.getOperand(1);
-  Constant *Mask = Shuf.getMask();
+  ArrayRef<int> Mask = Shuf.getShuffleMask();
   Value *X;
   uint64_t IndexC;
 
   // Match a shuffle that is a splat to a non-zero element.
   if (!match(Op0, m_OneUse(m_InsertElement(m_Undef(), m_Value(X),
                                            m_ConstantInt(IndexC)))) ||
-      !match(Op1, m_Undef()) || match(Mask, m_ZeroInt()) || IndexC == 0)
+      !match(Op1, m_Undef()) || match(Mask, m_ZeroMask()) || IndexC == 0)
     return nullptr;
 
   // Insert into element 0 of an undef vector.
@@ -1538,12 +1522,12 @@
   // shuf (inselt undef, X, 2), undef, <2,2,undef>
   //   --> shuf (inselt undef, X, 0), undef, <0,0,undef>
   unsigned NumMaskElts = Shuf.getType()->getVectorNumElements();
-  SmallVector<Constant *, 16> NewMask(NumMaskElts, Zero);
+  SmallVector<int, 16> NewMask(NumMaskElts, 0);
   for (unsigned i = 0; i != NumMaskElts; ++i)
-    if (isa<UndefValue>(Mask->getAggregateElement(i)))
-      NewMask[i] = Mask->getAggregateElement(i);
+    if (Mask[i] == UndefMaskElem)
+      NewMask[i] = Mask[i];
 
-  return new ShuffleVectorInst(NewIns, UndefVec, ConstantVector::get(NewMask));
+  return new ShuffleVectorInst(NewIns, UndefVec, NewMask);
 }
 
 /// Try to fold shuffles that are the equivalent of a vector select.
@@ -1612,14 +1596,14 @@
   BinaryOperator::BinaryOps BOpc = Opc0;
 
   // Select the constant elements needed for the single binop.
-  Constant *Mask = Shuf.getMask();
+  ArrayRef<int> Mask = Shuf.getShuffleMask();
   Constant *NewC = ConstantExpr::getShuffleVector(C0, C1, Mask);
 
   // We are moving a binop after a shuffle. When a shuffle has an undefined
   // mask element, the result is undefined, but it is not poison or undefined
   // behavior. That is not necessarily true for div/rem/shift.
   bool MightCreatePoisonOrUB =
-      Mask->containsUndefElement() &&
+      is_contained(Mask, UndefMaskElem) &&
       (Instruction::isIntDivRem(BOpc) || Instruction::isShift(BOpc));
   if (MightCreatePoisonOrUB)
     NewC = getSafeVectorConstantForBinop(BOpc, NewC, ConstantsAreOp1);
@@ -1668,7 +1652,7 @@
   NewBO->andIRFlags(B1);
   if (DropNSW)
     NewBO->setHasNoSignedWrap(false);
-  if (Mask->containsUndefElement() && !MightCreatePoisonOrUB)
+  if (is_contained(Mask, UndefMaskElem) && !MightCreatePoisonOrUB)
     NewBO->dropPoisonGeneratingFlags();
   return NewBO;
 }
@@ -1694,8 +1678,7 @@
   // and have the same number of elements as this shuffle.
   unsigned NarrowNumElts = Shuf.getType()->getVectorNumElements();
   Value *NarrowCond;
-  if (!match(Cond, m_OneUse(m_ShuffleVector(m_Value(NarrowCond), m_Undef(),
-                                            m_Constant()))) ||
+  if (!match(Cond, m_OneUse(m_ShuffleVector(m_Value(NarrowCond), m_Undef()))) ||
       NarrowCond->getType()->getVectorNumElements() != NarrowNumElts ||
       !cast<ShuffleVectorInst>(Cond)->isIdentityWithPadding())
     return nullptr;
@@ -1703,8 +1686,8 @@
   // shuf (sel (shuf NarrowCond, undef, WideMask), X, Y), undef, NarrowMask) -->
   // sel NarrowCond, (shuf X, undef, NarrowMask), (shuf Y, undef, NarrowMask)
   Value *Undef = UndefValue::get(X->getType());
-  Value *NarrowX = Builder.CreateShuffleVector(X, Undef, Shuf.getMask());
-  Value *NarrowY = Builder.CreateShuffleVector(Y, Undef, Shuf.getMask());
+  Value *NarrowX = Builder.CreateShuffleVector(X, Undef, Shuf.getShuffleMask());
+  Value *NarrowY = Builder.CreateShuffleVector(Y, Undef, Shuf.getShuffleMask());
   return SelectInst::Create(NarrowCond, NarrowX, NarrowY);
 }
 
@@ -1715,8 +1698,8 @@
     return nullptr;
 
   Value *X, *Y;
-  Constant *Mask;
-  if (!match(Op0, m_ShuffleVector(m_Value(X), m_Value(Y), m_Constant(Mask))))
+  ArrayRef<int> Mask;
+  if (!match(Op0, m_ShuffleVector(m_Value(X), m_Value(Y), m_Mask(Mask))))
     return nullptr;
 
   // Be conservative with shuffle transforms. If we can't kill the 1st shuffle,
@@ -1736,16 +1719,16 @@
   //   shuf (shuf X, Y, <C0, C1, C2, undef, C4>), undef, <0, undef, 2, 3> -->
   //   shuf X, Y, <C0, undef, C2, undef>
   unsigned NumElts = Shuf.getType()->getVectorNumElements();
-  SmallVector<Constant *, 16> NewMask(NumElts);
-  assert(NumElts < Mask->getType()->getVectorNumElements() &&
+  SmallVector<int, 16> NewMask(NumElts);
+  assert(NumElts < Mask.size() &&
          "Identity with extract must have less elements than its inputs");
 
   for (unsigned i = 0; i != NumElts; ++i) {
-    Constant *ExtractMaskElt = Shuf.getMask()->getAggregateElement(i);
-    Constant *MaskElt = Mask->getAggregateElement(i);
-    NewMask[i] = isa<UndefValue>(ExtractMaskElt) ? ExtractMaskElt : MaskElt;
+    int ExtractMaskElt = Shuf.getMaskValue(i);
+    int MaskElt = Mask[i];
+    NewMask[i] = ExtractMaskElt == UndefMaskElem ? ExtractMaskElt : MaskElt;
   }
-  return new ShuffleVectorInst(X, Y, ConstantVector::get(NewMask));
+  return new ShuffleVectorInst(X, Y, NewMask);
 }
 
 /// Try to replace a shuffle with an insertelement or try to replace a shuffle
@@ -1753,7 +1736,8 @@
 static Instruction *foldShuffleWithInsert(ShuffleVectorInst &Shuf,
                                           InstCombiner &IC) {
   Value *V0 = Shuf.getOperand(0), *V1 = Shuf.getOperand(1);
-  SmallVector<int, 16> Mask = Shuf.getShuffleMask();
+  SmallVector<int, 16> Mask;
+  Shuf.getShuffleMask(Mask);
 
   // The shuffle must not change vector sizes.
   // TODO: This restriction could be removed if the insert has only one use
@@ -1872,7 +1856,7 @@
   assert(WideElts > NarrowElts && "Unexpected types for identity with padding");
 
   Type *I32Ty = IntegerType::getInt32Ty(Shuf.getContext());
-  SmallVector<int, 16> Mask = Shuf.getShuffleMask();
+  ArrayRef<int> Mask = Shuf.getShuffleMask();
   SmallVector<Constant *, 16> NewMask(Mask.size(), UndefValue::get(I32Ty));
   for (int i = 0, e = Mask.size(); i != e; ++i) {
     if (Mask[i] == -1)
@@ -1905,28 +1889,28 @@
 Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
   Value *LHS = SVI.getOperand(0);
   Value *RHS = SVI.getOperand(1);
-  if (auto *V = SimplifyShuffleVectorInst(
-          LHS, RHS, SVI.getMask(), SVI.getType(), SQ.getWithInstruction(&SVI)))
+  if (auto *V =
+          SimplifyShuffleVectorInst(LHS, RHS, SVI.getShuffleMask(),
+                                    SVI.getType(), SQ.getWithInstruction(&SVI)))
     return replaceInstUsesWith(SVI, V);
 
   // shuffle x, x, mask --> shuffle x, undef, mask'
   unsigned VWidth = SVI.getType()->getVectorNumElements();
   unsigned LHSWidth = LHS->getType()->getVectorNumElements();
-  SmallVector<int, 16> Mask = SVI.getShuffleMask();
+  ArrayRef<int> Mask = SVI.getShuffleMask();
   Type *Int32Ty = Type::getInt32Ty(SVI.getContext());
   if (LHS == RHS) {
     assert(!isa<UndefValue>(RHS) && "Shuffle with 2 undef ops not simplified?");
     // Remap any references to RHS to use LHS.
-    SmallVector<Constant*, 16> Elts;
+    SmallVector<int, 16> Elts;
     for (unsigned i = 0; i != VWidth; ++i) {
       // Propagate undef elements or force mask to LHS.
       if (Mask[i] < 0)
-        Elts.push_back(UndefValue::get(Int32Ty));
+        Elts.push_back(UndefMaskElem);
       else
-        Elts.push_back(ConstantInt::get(Int32Ty, Mask[i] % LHSWidth));
+        Elts.push_back(Mask[i] % LHSWidth);
     }
-    return new ShuffleVectorInst(LHS, UndefValue::get(RHS->getType()),
-                                 ConstantVector::get(Elts));
+    return new ShuffleVectorInst(LHS, UndefValue::get(RHS->getType()), Elts);
   }
 
   // shuffle undef, x, mask --> shuffle x, undef, mask'
@@ -2151,8 +2135,8 @@
   if (newLHS == LHS && newRHS == RHS)
     return MadeChange ? &SVI : nullptr;
 
-  SmallVector<int, 16> LHSMask;
-  SmallVector<int, 16> RHSMask;
+  ArrayRef<int> LHSMask;
+  ArrayRef<int> RHSMask;
   if (newLHS != LHS)
     LHSMask = LHSShuffle->getShuffleMask();
   if (RHSShuffle && newRHS != RHS)
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1534,9 +1534,10 @@
   // narrow binop on each pair of the source operands followed by concatenation
   // of the results.
   Value *L0, *L1, *R0, *R1;
-  Constant *Mask;
-  if (match(LHS, m_ShuffleVector(m_Value(L0), m_Value(L1), m_Constant(Mask))) &&
-      match(RHS, m_ShuffleVector(m_Value(R0), m_Value(R1), m_Specific(Mask))) &&
+  ArrayRef<int> Mask;
+  if (match(LHS, m_ShuffleVector(m_Value(L0), m_Value(L1), m_Mask(Mask))) &&
+      match(RHS,
+            m_ShuffleVector(m_Value(R0), m_Value(R1), m_SpecificMask(Mask))) &&
       LHS->hasOneUse() && RHS->hasOneUse() &&
       cast<ShuffleVectorInst>(LHS)->isConcat() &&
       cast<ShuffleVectorInst>(RHS)->isConcat()) {
@@ -1560,7 +1561,7 @@
   if (!isSafeToSpeculativelyExecute(&Inst))
     return nullptr;
 
-  auto createBinOpShuffle = [&](Value *X, Value *Y, Constant *M) {
+  auto createBinOpShuffle = [&](Value *X, Value *Y, ArrayRef<int> M) {
     Value *XY = Builder.CreateBinOp(Opcode, X, Y);
     if (auto *BO = dyn_cast<BinaryOperator>(XY))
       BO->copyIRFlags(&Inst);
@@ -1570,8 +1571,9 @@
   // If both arguments of the binary operation are shuffles that use the same
   // mask and shuffle within a single vector, move the shuffle after the binop.
   Value *V1, *V2;
-  if (match(LHS, m_ShuffleVector(m_Value(V1), m_Undef(), m_Constant(Mask))) &&
-      match(RHS, m_ShuffleVector(m_Value(V2), m_Undef(), m_Specific(Mask))) &&
+  if (match(LHS, m_ShuffleVector(m_Value(V1), m_Undef(), m_Mask(Mask))) &&
+      match(RHS,
+            m_ShuffleVector(m_Value(V2), m_Undef(), m_SpecificMask(Mask))) &&
       V1->getType() == V2->getType() &&
       (LHS->hasOneUse() || RHS->hasOneUse() || LHS == RHS)) {
     // Op(shuffle(V1, Mask), shuffle(V2, Mask)) -> shuffle(Op(V1, V2), Mask)
@@ -1581,17 +1583,19 @@
   // If both arguments of a commutative binop are select-shuffles that use the
   // same mask with commuted operands, the shuffles are unnecessary.
   if (Inst.isCommutative() &&
-      match(LHS, m_ShuffleVector(m_Value(V1), m_Value(V2), m_Constant(Mask))) &&
+      match(LHS, m_ShuffleVector(m_Value(V1), m_Value(V2), m_Mask(Mask))) &&
       match(RHS, m_ShuffleVector(m_Specific(V2), m_Specific(V1),
-                                 m_Specific(Mask)))) {
+                                 m_SpecificMask(Mask)))) {
     auto *LShuf = cast<ShuffleVectorInst>(LHS);
     auto *RShuf = cast<ShuffleVectorInst>(RHS);
     // TODO: Allow shuffles that contain undefs in the mask?
     //       That is legal, but it reduces undef knowledge.
     // TODO: Allow arbitrary shuffles by shuffling after binop?
     //       That might be legal, but we have to deal with poison.
-    if (LShuf->isSelect() && !LShuf->getMask()->containsUndefElement() &&
-        RShuf->isSelect() && !RShuf->getMask()->containsUndefElement()) {
+    if (LShuf->isSelect() &&
+        !is_contained(LShuf->getShuffleMask(), UndefMaskElem) &&
+        RShuf->isSelect() &&
+        !is_contained(RShuf->getShuffleMask(), UndefMaskElem)) {
       // Example:
       // LHS = shuffle V1, V2, <0, 5, 6, 3>
       // RHS = shuffle V2, V1, <0, 5, 6, 3>
@@ -1608,9 +1612,9 @@
   // other binops, so they can be folded. It may also enable demanded elements
   // transforms.
   Constant *C;
-  if (match(&Inst, m_c_BinOp(
-          m_OneUse(m_ShuffleVector(m_Value(V1), m_Undef(), m_Constant(Mask))),
-          m_Constant(C))) &&
+  if (match(&Inst, m_c_BinOp(m_OneUse(m_ShuffleVector(m_Value(V1), m_Undef(),
+                                                      m_Mask(Mask))),
+                             m_Constant(C))) &&
       V1->getType()->getVectorNumElements() <= NumElts) {
     assert(Inst.getType()->getScalarType() == V1->getType()->getScalarType() &&
            "Shuffle should not change scalar type");
@@ -1621,8 +1625,7 @@
     // reorder is not possible. A 1-to-1 mapping is not required. Example:
     // ShMask = <1,1,2,2> and C = <5,5,6,6> --> NewC = <undef,5,6,undef>
     bool ConstOp1 = isa<Constant>(RHS);
-    SmallVector<int, 16> ShMask;
-    ShuffleVectorInst::getShuffleMask(Mask, ShMask);
+    ArrayRef<int> ShMask = Mask;
     unsigned SrcVecNumElts = V1->getType()->getVectorNumElements();
     UndefValue *UndefScalar = UndefValue::get(C->getType()->getScalarType());
     SmallVector<Constant *, 16> NewVecC(SrcVecNumElts, UndefScalar);
@@ -1687,12 +1690,12 @@
       std::swap(LHS, RHS);
 
     Value *X;
-    Constant *MaskC;
-    const APInt *SplatIndex;
+    ArrayRef<int> MaskC;
+    int SplatIndex;
     BinaryOperator *BO;
     if (!match(LHS, m_OneUse(m_ShuffleVector(m_Value(X), m_Undef(),
-                                             m_Constant(MaskC)))) ||
-        !match(MaskC, m_APIntAllowUndef(SplatIndex)) ||
+                                             m_Mask(MaskC)))) ||
+        !match(MaskC, m_SplatOrUndefMask(SplatIndex)) ||
         X->getType() != Inst.getType() || !match(RHS, m_OneUse(m_BinOp(BO))) ||
         BO->getOpcode() != Opcode)
       return nullptr;
@@ -1701,10 +1704,10 @@
     //        moving 'Y' before the splat shuffle, we are implicitly assuming
     //        that it is not undef/poison at the splat index.
     Value *Y, *OtherOp;
-    if (isSplatValue(BO->getOperand(0), SplatIndex->getZExtValue())) {
+    if (isSplatValue(BO->getOperand(0), SplatIndex)) {
       Y = BO->getOperand(0);
       OtherOp = BO->getOperand(1);
-    } else if (isSplatValue(BO->getOperand(1), SplatIndex->getZExtValue())) {
+    } else if (isSplatValue(BO->getOperand(1), SplatIndex)) {
       Y = BO->getOperand(1);
       OtherOp = BO->getOperand(0);
     } else {
@@ -1716,7 +1719,7 @@
     // bo (splat X), (bo Y, OtherOp) --> bo (splat (bo X, Y)), OtherOp
     Value *NewBO = Builder.CreateBinOp(Opcode, X, Y);
     UndefValue *Undef = UndefValue::get(Inst.getType());
-    Constant *NewMask = ConstantInt::get(MaskC->getType(), *SplatIndex);
+    SmallVector<int, 8> NewMask(MaskC.size(), SplatIndex);
     Value *NewSplat = Builder.CreateShuffleVector(NewBO, Undef, NewMask);
     Instruction *R = BinaryOperator::Create(Opcode, NewSplat, OtherOp);
 
diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -1867,10 +1867,9 @@
   }
 
   void visitShuffleVectorInst(ShuffleVectorInst &I) {
-    insertShadowCheck(I.getOperand(2), &I);
     IRBuilder<> IRB(&I);
     setShadow(&I, IRB.CreateShuffleVector(getShadow(&I, 0), getShadow(&I, 1),
-              I.getOperand(2), "_msprop"));
+                                          I.getShuffleMask(), "_msprop"));
     setOriginForNaryOp(I);
   }
 
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -289,7 +289,7 @@
     e.commutative = true;
   }
 
-  if (CmpInst *C = dyn_cast<CmpInst>(I)) {
+  if (auto *C = dyn_cast<CmpInst>(I)) {
     // Sort the operand value numbers so x<y and y>x get the same value number.
     CmpInst::Predicate Predicate = C->getPredicate();
     if (e.varargs[0] > e.varargs[1]) {
@@ -298,10 +298,11 @@
     }
     e.opcode = (C->getOpcode() << 8) | Predicate;
     e.commutative = true;
-  } else if (InsertValueInst *E = dyn_cast<InsertValueInst>(I)) {
-    for (InsertValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
-         II != IE; ++II)
-      e.varargs.push_back(*II);
+  } else if (auto *E = dyn_cast<InsertValueInst>(I)) {
+    e.varargs.append(E->idx_begin(), E->idx_end());
+  } else if (auto *SVI = dyn_cast<ShuffleVectorInst>(I)) {
+    ArrayRef<int> ShuffleMask = SVI->getShuffleMask();
+    e.varargs.append(ShuffleMask.begin(), ShuffleMask.end());
   }
 
   return e;
@@ -1732,7 +1733,8 @@
     // instead of value numbers. Those index numbers should not be
     // translated.
     if ((i > 1 && Exp.opcode == Instruction::InsertValue) ||
-        (i > 0 && Exp.opcode == Instruction::ExtractValue))
+        (i > 0 && Exp.opcode == Instruction::ExtractValue) ||
+        (i > 1 && Exp.opcode == Instruction::ShuffleVector))
       continue;
     Exp.varargs[i] = phiTranslate(Pred, PhiBlock, Exp.varargs[i], Gvn);
   }
diff --git a/llvm/lib/Transforms/Scalar/GVNSink.cpp b/llvm/lib/Transforms/Scalar/GVNSink.cpp
--- a/llvm/lib/Transforms/Scalar/GVNSink.cpp
+++ b/llvm/lib/Transforms/Scalar/GVNSink.cpp
@@ -350,6 +350,7 @@
 class InstructionUseExpr : public GVNExpression::BasicExpression {
   unsigned MemoryUseOrder = -1;
   bool Volatile = false;
+  std::vector<int> ShuffleMask;
 
 public:
   InstructionUseExpr(Instruction *I, ArrayRecycler<Value *> &R,
@@ -366,15 +367,18 @@
 
   void setMemoryUseOrder(unsigned MUO) { MemoryUseOrder = MUO; }
   void setVolatile(bool V) { Volatile = V; }
+  void setShuffleMask(ArrayRef<int> Mask) {
+    ShuffleMask.assign(Mask.begin(), Mask.end());
+  }
 
   hash_code getHashValue() const override {
     return hash_combine(GVNExpression::BasicExpression::getHashValue(),
-                        MemoryUseOrder, Volatile);
+                        MemoryUseOrder, Volatile, ArrayRef<int>(ShuffleMask));
   }
 
   template <typename Function> hash_code getHashValue(Function MapFn) {
-    hash_code H =
-        hash_combine(getOpcode(), getType(), MemoryUseOrder, Volatile);
+    hash_code H = hash_combine(getOpcode(), getType(), MemoryUseOrder, Volatile,
+                               ArrayRef<int>(ShuffleMask));
     for (auto *V : operands())
       H = hash_combine(H, MapFn(V));
     return H;
@@ -402,6 +406,8 @@
       CmpInst::Predicate Predicate = C->getPredicate();
       E->setOpcode((C->getOpcode() << 8) | Predicate);
     }
+    if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
+      E->setShuffleMask(SVI->getShuffleMask());
     return E;
   }
 
diff --git a/llvm/lib/Transforms/Scalar/NewGVN.cpp b/llvm/lib/Transforms/Scalar/NewGVN.cpp
--- a/llvm/lib/Transforms/Scalar/NewGVN.cpp
+++ b/llvm/lib/Transforms/Scalar/NewGVN.cpp
@@ -2030,10 +2030,12 @@
     case Instruction::Select:
     case Instruction::ExtractElement:
     case Instruction::InsertElement:
-    case Instruction::ShuffleVector:
     case Instruction::GetElementPtr:
       E = createExpression(I);
       break;
+    case Instruction::ShuffleVector:
+      // FIXME: Add support for shufflevector to createExpression.
+      return nullptr;
     default:
       return nullptr;
     }
diff --git a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
--- a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -1009,7 +1009,7 @@
         auto *SV = cast<ShuffleVectorInst>(I);
         UndefValue *VecUndef = UndefValue::get(SV->getOperand(0)->getType());
         std::string Name = suffixed_name_or(I, ".base", "base_sv");
-        return new ShuffleVectorInst(VecUndef, VecUndef, SV->getOperand(2),
+        return new ShuffleVectorInst(VecUndef, VecUndef, SV->getShuffleMask(),
                                      Name, SV);
       }
     };
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -3405,7 +3405,7 @@
         auto *O1 = B.CreateZExtOrTrunc(
             SI->getOperand(1), VectorType::get(ScalarTruncatedTy, Elements1));
 
-        NewI = B.CreateShuffleVector(O0, O1, SI->getMask());
+        NewI = B.CreateShuffleVector(O0, O1, SI->getShuffleMask());
       } else if (isa<LoadInst>(I) || isa<PHINode>(I)) {
         // Don't do anything with the operands, just extend the result.
         continue;
diff --git a/llvm/unittests/IR/PatternMatch.cpp b/llvm/unittests/IR/PatternMatch.cpp
--- a/llvm/unittests/IR/PatternMatch.cpp
+++ b/llvm/unittests/IR/PatternMatch.cpp
@@ -991,31 +991,32 @@
   EXPECT_TRUE(match(EX3, m_ExtractElement(m_Constant(), m_ConstantInt())));
 
   // Test matching shufflevector
-  EXPECT_TRUE(match(SI1, m_ShuffleVector(m_Value(), m_Undef(), m_Zero())));
-  EXPECT_TRUE(match(SI2, m_ShuffleVector(m_Value(A), m_Value(B), m_Value(C))));
+  ArrayRef<int> Mask;
+  EXPECT_TRUE(match(SI1, m_ShuffleVector(m_Value(), m_Undef(), m_ZeroMask())));
+  EXPECT_TRUE(
+      match(SI2, m_ShuffleVector(m_Value(A), m_Value(B), m_Mask(Mask))));
   EXPECT_TRUE(A == VI3);
   EXPECT_TRUE(B == VI4);
-  EXPECT_TRUE(C == IdxVec);
   A = B = C = nullptr; // reset
 
   // Test matching the vector splat pattern
   EXPECT_TRUE(match(
       SI1,
       m_ShuffleVector(m_InsertElement(m_Undef(), m_SpecificInt(1), m_Zero()),
-                      m_Undef(), m_Zero())));
+                      m_Undef(), m_ZeroMask())));
   EXPECT_FALSE(match(
       SI3, m_ShuffleVector(m_InsertElement(m_Undef(), m_Value(), m_Zero()),
-                           m_Undef(), m_Zero())));
+                           m_Undef(), m_ZeroMask())));
   EXPECT_FALSE(match(
       SI4, m_ShuffleVector(m_InsertElement(m_Undef(), m_Value(), m_Zero()),
-                           m_Undef(), m_Zero())));
+                           m_Undef(), m_ZeroMask())));
   EXPECT_TRUE(match(
       SP1,
       m_ShuffleVector(m_InsertElement(m_Undef(), m_SpecificInt(2), m_Zero()),
-                      m_Undef(), m_Zero())));
+                      m_Undef(), m_ZeroMask())));
   EXPECT_TRUE(match(
       SP2, m_ShuffleVector(m_InsertElement(m_Undef(), m_Value(A), m_Zero()),
-                           m_Undef(), m_Zero())));
+                           m_Undef(), m_ZeroMask())));
   EXPECT_TRUE(A == Val);
 }