diff --git a/llvm/lib/Analysis/MemorySSAUpdater.cpp b/llvm/lib/Analysis/MemorySSAUpdater.cpp
--- a/llvm/lib/Analysis/MemorySSAUpdater.cpp
+++ b/llvm/lib/Analysis/MemorySSAUpdater.cpp
@@ -1376,10 +1376,23 @@
           MP->unorderedDeleteIncomingBlock(BB);
           tryRemoveTrivialPhi(MP);
         }
-    // Drop all references of all accesses in BB
+
+    // Drop all references of all accesses in BB and remove those accesses from
+    // MemoryPhis outside of the dead blocks.
     if (MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB))
-      for (MemoryAccess &MA : *Acc)
+      for (MemoryAccess &MA : *Acc) {
         MA.dropAllReferences();
+
+        for (auto UI = MA.use_begin(), UE = MA.use_end(); UI != UE;) {
+          auto &U = *UI++;
+          auto *MemPhi = dyn_cast_or_null<MemoryPhi>(U.getUser());
+          if (!MemPhi || DeadBlocks.contains(MemPhi->getBlock()))
+            continue;
+          MemPhi->unorderedDeleteIncomingIf(
+              [&MA](MemoryAccess *Acc, BasicBlock *BB) { return &MA == Acc; });
+          tryRemoveTrivialPhi(MemPhi);
+        }
+      }
   }
 
   // Next, delete all memory accesses in each block
diff --git a/llvm/test/Analysis/MemorySSA/update-remove-dead-blocks.ll b/llvm/test/Analysis/MemorySSA/update-remove-dead-blocks.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Analysis/MemorySSA/update-remove-dead-blocks.ll
@@ -0,0 +1,46 @@
+; RUN: opt -loop-unswitch -loop-reduce -loop-simplifycfg -verify-memoryssa -S %s | FileCheck %s
+
+; TODO: also run with NPM, but currently LSR does not preserve LCSSA, causing a verification failure on the test.
+;   opt -passes='loop-mssa(unswitch<nontrivial>,loop-reduce,simplify-cfg)' -verify-memoryssa -S %s | FileCheck %s
+
+; Test case for PR47557.
+
+; REQUIRES: x86-registered-target
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = external global i32, align 4
+@c = external global [1 x i32], align 4
+
+define i32* @test() {
+; CHECK-LABEL: @test
+;
+entry:                                                ; preds = %entry
+  br label %for.cond
+
+for.cond:                                         ; preds = %cleanup, %entry
+  %storemerge = phi i64 [ 0, %entry ], [ %inc7, %cleanup ]
+  br label %for.cond2.1
+
+for.body3:                                        ; preds = %for.cond2.2, %for.cond2.1
+  %arrayidx = getelementptr inbounds [1 x i32], [1 x i32]* @c, i64 0, i64 %storemerge
+  ret i32* %arrayidx
+
+cleanup:                                          ; preds = %for.end5, %if.then
+  %inc7 = add nsw i64 %storemerge, 1
+  br label %for.cond
+
+for.cond2.1:                                      ; preds = %for.cond
+  br i1 true, label %for.inc.1, label %for.body3
+
+for.inc.1:                                        ; preds = %for.end.1
+  br i1 false, label %for.body.2, label %cleanup
+
+for.body.2:                                       ; preds = %for.inc.1
+  store i32 0, i32* @a, align 4
+  br label %for.cond2.2
+
+for.cond2.2:                                      ; preds = %for.body.2
+  br i1 true, label %cleanup, label %for.body3
+}