diff --git a/llvm/include/llvm/IR/Intrinsics.h b/llvm/include/llvm/IR/Intrinsics.h
--- a/llvm/include/llvm/IR/Intrinsics.h
+++ b/llvm/include/llvm/IR/Intrinsics.h
@@ -222,6 +222,12 @@
   /// This method returns true on error.
   bool matchIntrinsicVarArg(bool isVarArg, ArrayRef<IITDescriptor> &Infos);
 
+  /// Gets the type arguments of an intrinsic call by matching type contraints
+  /// specified by the .td file.
+  ///
+  /// Returns None if the given function is not a valid intrinsic call.
+  Optional<SmallVector<Type *, 4>> getIntrinsicSignature(Function *F);
+
   // Checks if the intrinsic name matches with its signature and if not
   // returns the declaration with the same signature and remangled name.
   llvm::Optional<Function*> remangleIntrinsicFunction(Function *F);
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -1427,31 +1427,41 @@
   return true;
 }
 
-Optional<Function*> Intrinsic::remangleIntrinsicFunction(Function *F) {
+Optional<SmallVector<Type *, 4>> Intrinsic::getIntrinsicSignature(Function *F) {
   Intrinsic::ID ID = F->getIntrinsicID();
   if (!ID)
     return None;
 
-  FunctionType *FTy = F->getFunctionType();
-  // Accumulate an array of overloaded types for the given intrinsic
+  SmallVector<Intrinsic::IITDescriptor, 8> Table;
+  getIntrinsicInfoTableEntries(ID, Table);
+  ArrayRef<Intrinsic::IITDescriptor> TableRef = Table;
   SmallVector<Type *, 4> ArgTys;
-  {
-    SmallVector<Intrinsic::IITDescriptor, 8> Table;
-    getIntrinsicInfoTableEntries(ID, Table);
-    ArrayRef<Intrinsic::IITDescriptor> TableRef = Table;
-
-    if (Intrinsic::matchIntrinsicSignature(FTy, TableRef, ArgTys))
-      return None;
-    if (Intrinsic::matchIntrinsicVarArg(FTy->isVarArg(), TableRef))
-      return None;
+
+  if (Intrinsic::matchIntrinsicSignature(F->getFunctionType(), TableRef,
+                                         ArgTys) !=
+      Intrinsic::MatchIntrinsicTypesResult::MatchIntrinsicTypes_Match) {
+    return None;
   }
+  if (Intrinsic::matchIntrinsicVarArg(F->getFunctionType()->isVarArg(),
+                                      TableRef))
+    return None;
+
+  return std::move(ArgTys);
+}
+
+Optional<Function *> Intrinsic::remangleIntrinsicFunction(Function *F) {
+  Optional<SmallVector<Type *, 4>> ArgTys = getIntrinsicSignature(F);
+  if (!ArgTys)
+    return None;
 
+  Intrinsic::ID ID = F->getIntrinsicID();
   StringRef Name = F->getName();
-  if (Name == Intrinsic::getName(ID, ArgTys))
+  if (Name == Intrinsic::getName(ID, *ArgTys))
     return None;
 
-  auto NewDecl = Intrinsic::getDeclaration(F->getParent(), ID, ArgTys);
+  auto NewDecl = Intrinsic::getDeclaration(F->getParent(), ID, *ArgTys);
   NewDecl->setCallingConv(F->getCallingConv());
+  FunctionType *FTy = F->getFunctionType();
   assert(NewDecl->getFunctionType() == FTy && "Shouldn't change the signature");
   return NewDecl;
 }
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
@@ -1130,25 +1130,21 @@
     return nullptr;
   }
 
-  // Determine the overload types of the original intrinsic.
-  auto IID = II->getIntrinsicID();
-  SmallVector<Intrinsic::IITDescriptor, 16> Table;
-  getIntrinsicInfoTableEntries(IID, Table);
-  ArrayRef<Intrinsic::IITDescriptor> TableRef = Table;
-
   // Validate function argument and return types, extracting overloaded types
   // along the way.
-  FunctionType *FTy = II->getCalledFunction()->getFunctionType();
-  SmallVector<Type *, 6> OverloadTys;
-  Intrinsic::matchIntrinsicSignature(FTy, TableRef, OverloadTys);
+  Optional<SmallVector<Type *, 4>> OverloadTys =
+      Intrinsic::getIntrinsicSignature(II->getCalledFunction());
+  if (!OverloadTys)
+    return nullptr;
 
   Module *M = II->getParent()->getParent()->getParent();
   Type *EltTy = IIVTy->getElementType();
   Type *NewTy =
       (NewNumElts == 1) ? EltTy : FixedVectorType::get(EltTy, NewNumElts);
 
-  OverloadTys[0] = NewTy;
-  Function *NewIntrin = Intrinsic::getDeclaration(M, IID, OverloadTys);
+  (*OverloadTys)[0] = NewTy;
+  Function *NewIntrin =
+      Intrinsic::getDeclaration(M, II->getIntrinsicID(), *OverloadTys);
 
   CallInst *NewCall = Builder.CreateCall(NewIntrin, Args);
   NewCall->takeName(II);