Index: lib/Analysis/LazyValueInfo.cpp
===================================================================
--- lib/Analysis/LazyValueInfo.cpp
+++ lib/Analysis/LazyValueInfo.cpp
@@ -1344,6 +1344,15 @@
   if (I != Visited.end())
     return I->second;
 
+  // Add a pessimistic initial result to avoid infinite recursion in case
+  // we find self referencing stuff like:
+  //
+  //  %0 = and i1 %0, %1
+  //
+  // The above is legal, as long as the instruction is not reachable from the
+  // entry bb.
+  Visited[Cond] = LVILatticeVal::getOverdefined();
+
   auto Result = getValueFromConditionImpl(Val, Cond, isTrueDest, Visited);
   Visited[Cond] = Result;
   return Result;
Index: test/Transforms/JumpThreading/PR33357-lvi-recursion.ll
===================================================================
--- /dev/null
+++ test/Transforms/JumpThreading/PR33357-lvi-recursion.ll
@@ -0,0 +1,42 @@
+; RUN: opt -S -jump-threading -verify -o - %s | FileCheck %s
+
+; Don't enter infinite recursion in LazyValueInfo.cpp
+
+@a = external global i16, align 1
+
+define void @f(i32 %p1) {
+bb0:
+  %0 = icmp eq i32 %p1, 0
+  br i1 undef, label %bb6, label %bb1
+
+bb1:                                         ; preds = %bb0
+  br label %bb2
+
+bb2:                                         ; preds = %bb4, %bb1
+  %1 = phi i1 [ %0, %bb1 ], [ %2, %bb4 ]
+  %2 = and i1 %1, undef
+  br i1 %2, label %bb3, label %bb4
+
+bb3:                                         ; preds = %bb2
+  store i16 undef, i16* @a, align 1
+  br label %bb4
+
+bb4:                                         ; preds = %bb3, %bb2
+  br i1 %0, label %bb2, label %bb5
+
+bb5:                                         ; preds = %bb4
+  unreachable
+
+bb6:                                         ; preds = %bb0
+  ret void
+}
+
+; The
+;  br i1 undef, label %bb6, label %bb1
+; is replaced by
+;  br label %bb6
+; and the rest of the function is unreachable from entry.
+
+; CHECK:      define void @f(i32 %p1) {
+; CHECK-NEXT: bb6:
+; CHECK-NEXT:   ret void