Index: include/llvm/Analysis/LoopInfoImpl.h
===================================================================
--- include/llvm/Analysis/LoopInfoImpl.h
+++ include/llvm/Analysis/LoopInfoImpl.h
@@ -636,6 +636,9 @@
     LoopT *L = Entry.second;
     assert(Loops.count(L) && "orphaned loop");
     assert(L->contains(BB) && "orphaned block");
+    for (LoopT *ChildLoop : *L)
+      assert(!ChildLoop->contains(BB) &&
+             "BBMap should point to the deepest loop containing BB");
   }
 
   // Recompute LoopInfo to verify loops structure.