Index: lib/Analysis/ScalarEvolution.cpp
===================================================================
--- lib/Analysis/ScalarEvolution.cpp
+++ lib/Analysis/ScalarEvolution.cpp
@@ -8394,8 +8394,11 @@
 ScalarEvolution::~ScalarEvolution() {
   // Iterate through all the SCEVUnknown instances and call their
   // destructors, so that they release their references to their values.
-  for (SCEVUnknown *U = FirstUnknown; U; U = U->Next)
-    U->~SCEVUnknown();
+  for (SCEVUnknown *U = FirstUnknown; U;) {
+    SCEVUnknown *tmp = U;
+    U = U->Next;
+    tmp->~SCEVUnknown();
+  }
   FirstUnknown = nullptr;
 
   ValueExprMap.clear();