diff --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -629,6 +629,7 @@
   const SCEV *getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
                                     unsigned Depth = 0);
   const SCEV *getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth = 0);
+  const SCEV *getSignExtendExprImpl(const SCEV *Op, Type *Ty, unsigned Depth = 0);
   const SCEV *getCastExpr(SCEVTypes Kind, const SCEV *Op, Type *Ty);
   const SCEV *getAnyExtendExpr(const SCEV *Op, Type *Ty);
   const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -1930,6 +1930,32 @@
   assert(!Op->getType()->isPointerTy() && "Can't extend pointer!");
   Ty = getEffectiveSCEVType(Ty);
 
+  FoldID ID;
+  ID.addInteger(scSignExtend);
+  ID.addPointer(Op);
+  ID.addPointer(Ty);
+  auto Iter = FoldCache.insert({ID, nullptr});
+  if (Iter.second || !Iter.first->second) {
+    auto *S = getSignExtendExprImpl(Op, Ty, Depth);
+
+    Iter = FoldCache.insert({ID, nullptr});
+    Iter.first->second = S;
+
+    auto R = FoldCacheUser.insert({S, {}});
+    R.first->second.push_back(ID);
+  }
+  return Iter.first->second;
+}
+
+const SCEV *
+ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty, unsigned Depth) {
+  assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
+         "This is not an extending conversion!");
+  assert(isSCEVable(Ty) &&
+         "This is not a conversion to a SCEVable type!");
+  assert(!Op->getType()->isPointerTy() && "Can't extend pointer!");
+  Ty = getEffectiveSCEVType(Ty);
+
   // Fold if the operand is constant.
   if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
     return getConstant(