Index: llvm/lib/Transforms/Scalar/JumpThreading.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -453,6 +453,9 @@
         LVI->eraseBlock(&BB);
         DeleteDeadBlock(&BB, DTU);
         Changed = true;
+        // The alias analysis may store dangling pointers to the deleted block,
+        // so we should not use it further.
+        AA = nullptr;
         continue;
       }
 
@@ -473,6 +476,7 @@
           // BB's parent until a DTU->getDomTree() event.
           LVI->eraseBlock(&BB);
           Changed = true;
+          AA = nullptr;
         }
       }
     }
@@ -1982,6 +1986,7 @@
 
   LVI->eraseBlock(SinglePred);
   MergeBasicBlockIntoOnlyPred(BB, DTU);
+  AA = nullptr;
 
   // Now that BB is merged into SinglePred (i.e. SinglePred code followed by
   // BB code within one basic block `BB`), we need to invalidate the LVI
Index: llvm/test/Transforms/JumpThreading/pr43276.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/JumpThreading/pr43276.ll
@@ -0,0 +1,88 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S < %s -jump-threading | FileCheck %s
+; RUN: opt -S < %s -passes=jump-threading | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:1"
+target triple = "x86_64-unknown-linux-gnu"
+
+@global = external global i8*
+
+define i32 @wibble() {
+; CHECK-LABEL: @wibble(
+; CHECK-NEXT:  bb19:
+; CHECK-NEXT:    [[TMP20:%.*]] = getelementptr i8, i8* undef, i64 16
+; CHECK-NEXT:    [[TMP21:%.*]] = load atomic i8*, i8** @global unordered, align 8
+; CHECK-NEXT:    [[TMP22:%.*]] = getelementptr inbounds i8, i8* [[TMP21]], i64 936
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[TMP:%.*]] = phi i8* [ [[TMP22]], [[BB19:%.*]] ], [ undef, [[BB2:%.*]] ]
+; CHECK-NEXT:    [[TMP4:%.*]] = phi i8* [ [[TMP21]], [[BB19]] ], [ undef, [[BB2]] ]
+; CHECK-NEXT:    [[TMP5:%.*]] = bitcast i8* [[TMP]] to i64*
+; CHECK-NEXT:    [[TMP6:%.*]] = getelementptr inbounds i8, i8* [[TMP4]], i64 848
+; CHECK-NEXT:    [[TMP7:%.*]] = bitcast i8* [[TMP6]] to i8**
+; CHECK-NEXT:    br label [[BB11:%.*]]
+; CHECK:       bb11:
+; CHECK-NEXT:    [[TMP12:%.*]] = load atomic i8*, i8** [[TMP7]] unordered, align 8
+; CHECK-NEXT:    [[TMP13:%.*]] = icmp eq i8* [[TMP12]], null
+; CHECK-NEXT:    br i1 [[TMP13]], label [[BB17:%.*]], label [[BB16:%.*]]
+; CHECK:       bb16:
+; CHECK-NEXT:    store atomic i64 undef, i64* [[TMP5]] unordered, align 8
+; CHECK-NEXT:    br label [[BB11]]
+; CHECK:       bb17:
+; CHECK-NEXT:    ret i32 undef
+;
+bb:
+  br label %bb1
+
+bb1:                                              ; preds = %bb
+  br label %bb18
+
+bb2:                                              ; No predecessors!
+  br label %bb3
+
+bb3:                                              ; preds = %bb19, %bb2
+  %tmp = phi i8* [ %tmp22, %bb19 ], [ undef, %bb2 ]
+  %tmp4 = phi i8* [ %tmp21, %bb19 ], [ undef, %bb2 ]
+  %tmp5 = bitcast i8* %tmp to i64*
+  %tmp6 = getelementptr inbounds i8, i8* %tmp4, i64 848
+  %tmp7 = bitcast i8* %tmp6 to i8**
+  br label %bb11
+
+bb11:                                             ; preds = %bb16, %bb3
+  %tmp12 = load atomic i8*, i8** %tmp7 unordered, align 8
+  %tmp13 = icmp eq i8* %tmp12, null
+  br i1 %tmp13, label %bb17, label %bb14
+
+bb14:                                             ; preds = %bb11
+  br label %bb15
+
+bb15:                                             ; preds = %bb14
+  br label %bb16
+
+bb16:                                             ; preds = %bb15
+  store atomic i64 undef, i64* %tmp5 unordered, align 8
+  br label %bb11
+
+bb17:                                             ; preds = %bb11
+  ret i32 undef
+
+bb18:                                             ; preds = %bb1
+  br label %bb19
+
+bb19:                                             ; preds = %bb18
+  %tmp20 = getelementptr i8, i8* undef, i64 16
+  %tmp21 = load atomic i8*, i8** @global unordered, align 8
+  %tmp22 = getelementptr inbounds i8, i8* %tmp21, i64 936
+  br label %bb3
+}
+
+define void @zot(i8* align 8 dereferenceable_or_null(16) %arg, i32 %arg1) {
+; CHECK-LABEL: @zot(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    ret void
+;
+bb:
+  ret void
+}
Index: llvm/test/Transforms/JumpThreading/thread-loads.ll
===================================================================
--- llvm/test/Transforms/JumpThreading/thread-loads.ll
+++ llvm/test/Transforms/JumpThreading/thread-loads.ll
@@ -466,10 +466,7 @@
 ; CHECK-NEXT:    store i32* [[CALL_I62]], i32** [[ARRAYIDX89]], align 8
 ; CHECK-NEXT:    [[L2:%.*]] = load i32, i32* [[ARRAYIDX185]], align 4
 ; CHECK-NEXT:    [[TOBOOL_I63:%.*]] = icmp eq i32 [[L2]], 0
-; CHECK-NEXT:    br i1 [[TOBOOL_I63]], label [[SW_BB21_I_THREAD:%.*]], label [[IF_THEN_I64:%.*]]
-; CHECK:       sw.bb21.i.thread:
-; CHECK-NEXT:    store i32 10, i32* [[PHASE]], align 8
-; CHECK-NEXT:    br label [[DO_BODY_PREHEADER_I67:%.*]]
+; CHECK-NEXT:    br i1 [[TOBOOL_I63]], label [[SW_BB21_I]], label [[IF_THEN_I64:%.*]]
 ; CHECK:       if.then.i64:
 ; CHECK-NEXT:    store i32 7, i32* [[PHASE]], align 8
 ; CHECK-NEXT:    store i32 [[L2]], i32* [[ARRAYIDX307]], align 4
@@ -480,10 +477,10 @@
 ; CHECK-NEXT:    call void @f65()
 ; CHECK-NEXT:    br label [[SW_BB21_I]]
 ; CHECK:       sw.bb21.i:
-; CHECK-NEXT:    [[L3_PR:%.*]] = load i32, i32* [[ARRAYIDX185]], align 4
 ; CHECK-NEXT:    store i32 10, i32* [[PHASE]], align 8
-; CHECK-NEXT:    [[TOBOOL27_I:%.*]] = icmp eq i32 [[L3_PR]], 0
-; CHECK-NEXT:    br i1 [[TOBOOL27_I]], label [[DO_BODY_PREHEADER_I67]], label [[CLEANUP]]
+; CHECK-NEXT:    [[L3:%.*]] = load i32, i32* [[ARRAYIDX185]], align 4
+; CHECK-NEXT:    [[TOBOOL27_I:%.*]] = icmp eq i32 [[L3]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL27_I]], label [[DO_BODY_PREHEADER_I67:%.*]], label [[CLEANUP]]
 ; CHECK:       do.body.preheader.i67:
 ; CHECK-NEXT:    call void @f67()
 ; CHECK-NEXT:    ret i32 67