diff --git a/lib/Transforms/Scalar/NewGVN.cpp b/lib/Transforms/Scalar/NewGVN.cpp
index f70ec40f045..9d018563618 100644
--- a/lib/Transforms/Scalar/NewGVN.cpp
+++ b/lib/Transforms/Scalar/NewGVN.cpp
@@ -2073,7 +2073,8 @@ void NewGVN::moveMemoryToNewCongruenceClass(Instruction *I,
   // be the MemoryAccess of OldClass.
   assert((!InstMA || !OldClass->getMemoryLeader() ||
           OldClass->getLeader() != I ||
-          OldClass->getMemoryLeader() == InstMA) &&
+          MemoryAccessToClass.lookup(OldClass->getMemoryLeader()) ==
+              MemoryAccessToClass.lookup(InstMA)) &&
          "Representative MemoryAccess mismatch");
   // First, see what happens to the new class
   if (!NewClass->getMemoryLeader()) {
diff --git a/test/Transforms/NewGVN/pr33720.ll b/test/Transforms/NewGVN/pr33720.ll
new file mode 100644
index 00000000000..3b6c190a449
--- /dev/null
+++ b/test/Transforms/NewGVN/pr33720.ll
@@ -0,0 +1,91 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -newgvn -S %s | FileCheck %s
+
+@f = external local_unnamed_addr global i64
+@b = external local_unnamed_addr global i64
+@e = external local_unnamed_addr global i64
+
+define void @patatino() {
+; CHECK-LABEL: @patatino(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 undef, label [[IF_END24:%.*]], label [[FOR_COND16:%.*]]
+; CHECK:       for.cond2thread-pre-split:
+; CHECK-NEXT:    br i1 false, label [[FOR_BODY:%.*]], label [[FOR_COND8_PREHEADER:%.*]]
+; CHECK:       for.cond8.preheader:
+; CHECK-NEXT:    br i1 undef, label [[L1:%.*]], label %for.cond11thread-pre-split.lr.ph
+; CHECK:       for.cond11thread-pre-split.lr.ph:
+; CHECK-NEXT:    br label [[L1]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[CMP3:%.*]] = icmp ne i64 [[K_2:%.*]], 3
+; CHECK-NEXT:    [[CONV4:%.*]] = zext i1 [[CMP3]] to i64
+; CHECK-NEXT:    [[TMP0:%.*]] = load i64, i64* @f
+; CHECK-NEXT:    [[OR:%.*]] = or i64 [[TMP0]], [[CONV4]]
+; CHECK-NEXT:    store i64 [[OR]], i64* @f
+; CHECK-NEXT:    [[TOBOOL7:%.*]] = icmp ne i64 [[K_2]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL7]], label %for.cond2thread-pre-split, label [[LOR_RHS:%.*]]
+; CHECK:       lor.rhs:
+; CHECK-NEXT:    store i64 1, i64* @b, align 8
+; CHECK-NEXT:    br label %for.cond2thread-pre-split
+; CHECK:       l1:
+; CHECK-NEXT:    [[K_2]] = phi i64 [ undef, [[L1_PREHEADER:%.*]] ], [ 15, [[FOR_COND8_PREHEADER]] ], [ 5, %for.cond11thread-pre-split.lr.ph ]
+; CHECK-NEXT:    store i64 7, i64* [[J_3:%.*]]
+; CHECK-NEXT:    br label [[FOR_BODY]]
+; CHECK:       for.cond16:
+; CHECK-NEXT:    [[J_0:%.*]] = phi i64* [ @f, [[ENTRY:%.*]] ], [ undef, [[FOR_COND20:%.*]] ], [ @e, [[FOR_COND16]] ]
+; CHECK-NEXT:    br i1 undef, label [[FOR_COND20]], label [[FOR_COND16]]
+; CHECK:       for.cond20:
+; CHECK-NEXT:    [[J_2:%.*]] = phi i64* [ [[J_0]], [[FOR_COND16]] ], [ undef, [[IF_END24]] ]
+; CHECK-NEXT:    br i1 true, label [[IF_END24]], label [[FOR_COND16]]
+; CHECK:       if.end24:
+; CHECK-NEXT:    [[J_3]] = phi i64* [ [[J_2]], [[FOR_COND20]] ], [ undef, [[ENTRY]] ]
+; CHECK-NEXT:    br i1 false, label [[FOR_COND20]], label [[L1_PREHEADER]]
+; CHECK:       l1.preheader:
+; CHECK-NEXT:    br label [[L1]]
+;
+entry:
+  br i1 undef, label %if.end24, label %for.cond16
+
+for.cond2thread-pre-split:
+  br i1 false, label %for.body, label %for.cond8.preheader
+
+for.cond8.preheader:
+  br i1 undef, label %l1, label %for.cond11thread-pre-split.lr.ph
+
+for.cond11thread-pre-split.lr.ph:
+  br label %l1
+
+for.body:
+  %k.031 = phi i64 [ %k.2, %l1 ], [ 15, %for.cond2thread-pre-split ]
+  %cmp3 = icmp ne i64 %k.031, 3
+  %conv4 = zext i1 %cmp3 to i64
+  %0 = load i64, i64* @f
+  %or = or i64 %0, %conv4
+  store i64 %or, i64* @f
+  %tobool7 = icmp ne i64 %k.031, 0
+  %or.cond = or i1 %tobool7, false
+  br i1 %or.cond, label %for.cond2thread-pre-split, label %lor.rhs
+
+lor.rhs:
+  store i64 1, i64* @b, align 8
+  br label %for.cond2thread-pre-split
+
+l1:
+  %k.2 = phi i64 [ undef, %l1.preheader ], [ 15, %for.cond8.preheader ], [ 5, %for.cond11thread-pre-split.lr.ph ]
+  store i64 7, i64* %j.3
+  br label %for.body
+
+for.cond16:
+  %j.0 = phi i64* [ @f, %entry ], [ %j.2, %for.cond20 ], [ @e, %for.cond16 ]
+  br i1 undef, label %for.cond20, label %for.cond16
+
+for.cond20:
+  %j.2 = phi i64* [ %j.0, %for.cond16 ], [ %j.3, %if.end24 ]
+  br i1 true, label %if.end24, label %for.cond16
+
+if.end24:
+  %j.3 = phi i64* [ %j.2, %for.cond20 ], [ undef, %entry ]
+  br i1 false, label %for.cond20, label %l1.preheader
+
+l1.preheader:
+  br label %l1
+}