diff --git a/llvm/include/llvm/Support/GenericDomTree.h b/llvm/include/llvm/Support/GenericDomTree.h
index 7e2b68e6faea29..45ef38b965b752 100644
--- a/llvm/include/llvm/Support/GenericDomTree.h
+++ b/llvm/include/llvm/Support/GenericDomTree.h
@@ -397,6 +397,8 @@ class DominatorTreeBase {
   /// may (but is not required to) be null for a forward (backwards)
   /// statically unreachable block.
   DomTreeNodeBase<NodeT> *getNode(const NodeT *BB) const {
+    assert((!BB || Parent == NodeTrait::getParent(const_cast<NodeT *>(BB))) &&
+           "cannot get DomTreeNode of block with different parent");
     if (auto Idx = getNodeIndex(BB); Idx && *Idx < DomTreeNodes.size())
       return DomTreeNodes[*Idx].get();
     return nullptr;
diff --git a/llvm/lib/Analysis/TypeMetadataUtils.cpp b/llvm/lib/Analysis/TypeMetadataUtils.cpp
index 67ce1540112bb7..9ec0785eb5034d 100644
--- a/llvm/lib/Analysis/TypeMetadataUtils.cpp
+++ b/llvm/lib/Analysis/TypeMetadataUtils.cpp
@@ -33,6 +33,8 @@ findCallsAtConstantOffset(SmallVectorImpl<DevirtCallSite> &DevirtCalls,
     // after indirect call promotion and inlining, where we may have uses
     // of the vtable pointer guarded by a function pointer check, and a fallback
     // indirect call.
+    if (CI->getFunction() != User->getFunction())
+      continue;
     if (!DT.dominates(CI, User))
       continue;
     if (isa<BitCastInst>(User)) {
diff --git a/llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp b/llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp
index f3422a705dca7a..8555ef5c22f827 100644
--- a/llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp
+++ b/llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp
@@ -208,6 +208,7 @@ bool AlignmentFromAssumptionsPass::processAssumption(CallInst *ACall,
       continue;
 
     if (Instruction *K = dyn_cast<Instruction>(J))
+      if (K->getFunction() == ACall->getFunction())
         WorkList.push_back(K);
   }
 
diff --git a/llvm/lib/Transforms/Scalar/LoopFuse.cpp b/llvm/lib/Transforms/Scalar/LoopFuse.cpp
index 8512b2accbe7c2..fe0e30d1965e05 100644
--- a/llvm/lib/Transforms/Scalar/LoopFuse.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopFuse.cpp
@@ -1729,7 +1729,9 @@ struct LoopFuser {
     // mergeLatch may remove the only block in FC1.
     SE.forgetLoop(FC1.L);
     SE.forgetLoop(FC0.L);
-    SE.forgetLoopDispositions();
+    // Forget block dispositions as well, so that there are no dangling
+    // pointers to erased/free'ed blocks.
+    SE.forgetBlockAndLoopDispositions();
 
     // Move instructions from FC0.Latch to FC1.Latch.
     // Note: mergeLatch requires an updated DT.
@@ -2023,7 +2025,9 @@ struct LoopFuser {
     // mergeLatch may remove the only block in FC1.
     SE.forgetLoop(FC1.L);
     SE.forgetLoop(FC0.L);
-    SE.forgetLoopDispositions();
+    // Forget block dispositions as well, so that there are no dangling
+    // pointers to erased/free'ed blocks.
+    SE.forgetBlockAndLoopDispositions();
 
     // Move instructions from FC0.Latch to FC1.Latch.
     // Note: mergeLatch requires an updated DT.
diff --git a/llvm/test/Transforms/AlignmentFromAssumptions/domtree-crash.ll b/llvm/test/Transforms/AlignmentFromAssumptions/domtree-crash.ll
new file mode 100644
index 00000000000000..c7fc1dc6996718
--- /dev/null
+++ b/llvm/test/Transforms/AlignmentFromAssumptions/domtree-crash.ll
@@ -0,0 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes=alignment-from-assumptions -S < %s | FileCheck %s
+
+; The alignment assumption is a global, which has users in a different
+; function. Test that in this case the dominator tree is only queried with
+; blocks from the same function.
+
+@global = external constant [192 x i8]
+
+define void @fn1() {
+; CHECK-LABEL: define void @fn1() {
+; CHECK-NEXT:    call void @llvm.assume(i1 false) [ "align"(ptr @global, i64 1) ]
+; CHECK-NEXT:    ret void
+;
+  call void @llvm.assume(i1 false) [ "align"(ptr @global, i64 1) ]
+  ret void
+}
+
+define void @fn2() {
+; CHECK-LABEL: define void @fn2() {
+; CHECK-NEXT:    ret void
+; CHECK:       [[LOOP:.*]]:
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds i8, ptr @global, i64 0
+; CHECK-NEXT:    [[LOAD:%.*]] = load i64, ptr [[GEP]], align 1
+; CHECK-NEXT:    br label %[[LOOP]]
+;
+  ret void
+
+loop:
+  %gep = getelementptr inbounds i8, ptr @global, i64 0
+  %load = load i64, ptr %gep, align 1
+  br label %loop
+}