Index: llvm/include/llvm/Transforms/IPO/Attributor.h
===================================================================
--- llvm/include/llvm/Transforms/IPO/Attributor.h
+++ llvm/include/llvm/Transforms/IPO/Attributor.h
@@ -715,6 +715,19 @@
   /// Return the map conaining all the knowledge we have from `llvm.assume`s.
   const RetainedKnowledgeMap &getKnowledgeMap() const { return KnowledgeMap; }
 
+  bool getPotentiallyReachable(const Instruction *From, const Instruction *To) {
+    auto KeyPair = std::make_pair(From, To);
+    auto Iter = PotentiallyReachableMap.find(KeyPair);
+    const Function &F = *From->getFunction();
+    if (Iter != PotentiallyReachableMap.end())
+      return Iter->second;
+    bool Result = isPotentiallyReachable(
+        From, To, nullptr, AG.getAnalysis<DominatorTreeAnalysis>(F),
+        AG.getAnalysis<LoopAnalysis>(F));
+    PotentiallyReachableMap.insert(std::make_pair(KeyPair, Result));
+    return Result;
+  }
+
 private:
   struct FunctionInfo {
     ~FunctionInfo();
@@ -774,6 +787,10 @@
   /// Set of inlineable functions
   SmallPtrSet<const Function *, 8> InlineableFunctions;
 
+  /// A map for caching results of queries for isPotentiallyReachable
+  DenseMap<std::pair<const Instruction *, const Instruction *>, bool>
+      PotentiallyReachableMap;
+
   /// Give the Attributor access to the members so
   /// Attributor::identifyDefaultAbstractAttributes(...) can initialize them.
   friend struct Attributor;
@@ -2291,16 +2308,21 @@
   /// Returns true if 'From' instruction is assumed to reach, 'To' instruction.
   /// Users should provide two positions they are interested in, and the class
   /// determines (and caches) reachability.
-  bool isAssumedReachable(const Instruction *From,
-                          const Instruction *To) const {
-    return isPotentiallyReachable(From, To);
+  bool isAssumedReachable(const Instruction *From, const Instruction *To,
+                          Attributor &A) const {
+    const auto &LivenessAA =
+        A.getAAFor<AAIsDead>(*this, IRPosition::value(*From));
+    if (A.isAssumedDead(*From, this, &LivenessAA))
+      return false;
+    return A.getInfoCache().getPotentiallyReachable(From, To);
   }
 
   /// Returns true if 'From' instruction is known to reach, 'To' instruction.
   /// Users should provide two positions they are interested in, and the class
   /// determines (and caches) reachability.
-  bool isKnownReachable(const Instruction *From, const Instruction *To) const {
-    return isPotentiallyReachable(From, To);
+  bool isKnownReachable(const Instruction *From, const Instruction *To,
+                        Attributor &A) const {
+    return A.getInfoCache().getPotentiallyReachable(From, To);
   }
 
   /// Create an abstract attribute view for the position \p IRP.
Index: llvm/lib/Transforms/IPO/AttributorAttributes.cpp
===================================================================
--- llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -2469,7 +2469,7 @@
         const auto &ReachabilityAA =
             A.getAAFor<AAReachability>(*this, IRPosition::function(*ScopeFn));
 
-        if (!ReachabilityAA.isAssumedReachable(UserI, getCtxI()))
+        if (!ReachabilityAA.isAssumedReachable(UserI, getCtxI(), A))
           return true;
 
         if (auto *CB = dyn_cast<CallBase>(UserI)) {