diff --git a/clang/test/CodeGen/debug-names-compound-type-units.ll b/clang/test/CodeGen/debug-names-compound-type-units.ll
new file mode 100644
index 0000000000000..0d85de286772a
--- /dev/null
+++ b/clang/test/CodeGen/debug-names-compound-type-units.ll
@@ -0,0 +1,73 @@
+; REQUIRES: asserts
+
+;; Tests that we use correct accelerator table when processing nested TUs.
+;; Assert is not triggered.
+;; File1
+;; struct Foo {
+;;   char f;
+;; };
+;; struct Foo2 {
+;;   char f;
+;;   Foo f1;
+;; };
+;; void fooFunc() {
+;; Foo2 global2;
+;; }
+;; clang++ <file>.cpp -O0 -g2 -fdebug-types-section -gpubnames -S -emit-llvm -o <file>.ll
+
+; RUN: llc -O0 -dwarf-version=5 -generate-type-units -filetype=obj < %s -o %t.o
+; RUN: llvm-readelf --sections %t.o | FileCheck --check-prefix=OBJ %s
+
+; OBJ: debug_names
+
+; ModuleID = 'main.cpp'
+source_filename = "main.cpp"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.Foo2 = type { i8, %struct.Foo }
+%struct.Foo = type { i8 }
+
+; Function Attrs: mustprogress noinline nounwind optnone uwtable
+define dso_local void @_Z7fooFuncv() #0 !dbg !10 {
+entry:
+  %global2 = alloca %struct.Foo2, align 1
+  call void @llvm.dbg.declare(metadata ptr %global2, metadata !14, metadata !DIExpression()), !dbg !23
+  ret void, !dbg !24
+}
+
+; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { mustprogress noinline nounwind optnone uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 18.0.0git", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false)
+!1 = !DIFile(filename: "main.cpp", directory: "/smallMultipleTUs", checksumkind: CSK_MD5, checksum: "70bff4d50322126f3d8ca4178afad376")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 7, !"frame-pointer", i32 2}
+!9 = !{!"clang version 18.0.0git"}
+!10 = distinct !DISubprogram(name: "fooFunc", linkageName: "_Z7fooFuncv", scope: !1, file: !1, line: 9, type: !11, scopeLine: 9, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !13)
+!11 = !DISubroutineType(types: !12)
+!12 = !{null}
+!13 = !{}
+!14 = !DILocalVariable(name: "global2", scope: !10, file: !1, line: 10, type: !15)
+!15 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Foo2", file: !1, line: 4, size: 16, flags: DIFlagTypePassByValue, elements: !16, identifier: "_ZTS4Foo2")
+!16 = !{!17, !19}
+!17 = !DIDerivedType(tag: DW_TAG_member, name: "f", scope: !15, file: !1, line: 5, baseType: !18, size: 8)
+!18 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!19 = !DIDerivedType(tag: DW_TAG_member, name: "f1", scope: !15, file: !1, line: 6, baseType: !20, size: 8, offset: 8)
+!20 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Foo", file: !1, line: 1, size: 8, flags: DIFlagTypePassByValue, elements: !21, identifier: "_ZTS3Foo")
+!21 = !{!22}
+!22 = !DIDerivedType(tag: DW_TAG_member, name: "f", scope: !20, file: !1, line: 2, baseType: !18, size: 8)
+!23 = !DILocation(line: 10, column: 6, scope: !10)
+!24 = !DILocation(line: 11, column: 1, scope: !10)
diff --git a/clang/test/CodeGen/thinlto-debug-names-tu-reuse.ll b/clang/test/CodeGen/thinlto-debug-names-tu-reuse.ll
new file mode 100644
index 0000000000000..53aec43a050f8
--- /dev/null
+++ b/clang/test/CodeGen/thinlto-debug-names-tu-reuse.ll
@@ -0,0 +1,58 @@
+; REQUIRES: asserts
+
+;; Tests that accelerator table switches correctly from TU to CU when a top level TU is re-used.
+;; Assert is not triggered.
+;; File1
+;; struct Foo {
+;;   char fChar;
+;; };
+;; Foo fGlobal;
+;; FIle2
+;; struct Foo {
+;;   char fChar;
+;; };
+;; Foo fGlobal2;
+;; clang++ <file>.cpp -O0 -g2 -fdebug-types-section -gpubnames -S -emit-llvm -o <file>.ll
+;; llvm-link file1.ll file2.ll -S -o thinlto-debug-names-tu-reuse.ll
+
+; RUN: llc -O0 -dwarf-version=5 -generate-type-units -filetype=obj < %s -o %t.o
+; RUN: llvm-readelf --sections %t.o | FileCheck --check-prefix=OBJ %s
+
+; OBJ: debug_names
+
+; ModuleID = 'llvm-link'
+source_filename = "llvm-link"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.Foo = type { i8 }
+
+@fGlobal = dso_local global %struct.Foo zeroinitializer, align 1, !dbg !0
+@fGlobal2 = dso_local global %struct.Foo zeroinitializer, align 1, !dbg !9
+
+!llvm.dbg.cu = !{!2, !11}
+!llvm.ident = !{!14, !14}
+!llvm.module.flags = !{!15, !16, !17, !18, !19, !20, !21}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "fGlobal", scope: !2, file: !3, line: 5, type: !5, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !3, producer: "clang version 18.0.0git", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, globals: !4, splitDebugInlining: false)
+!3 = !DIFile(filename: "main.cpp", directory: "/smallTUReuse", checksumkind: CSK_MD5, checksum: "4f1831504f0948b03880356fae49cb58")
+!4 = !{!0}
+!5 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Foo", file: !3, line: 2, size: 8, flags: DIFlagTypePassByValue, elements: !6, identifier: "_ZTS3Foo")
+!6 = !{!7}
+!7 = !DIDerivedType(tag: DW_TAG_member, name: "fChar", scope: !5, file: !3, line: 3, baseType: !8, size: 8)
+!8 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!9 = !DIGlobalVariableExpression(var: !10, expr: !DIExpression())
+!10 = distinct !DIGlobalVariable(name: "fGlobal2", scope: !11, file: !12, line: 5, type: !5, isLocal: false, isDefinition: true)
+!11 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !12, producer: "clang version 18.0.0git", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, globals: !13, splitDebugInlining: false)
+!12 = !DIFile(filename: "helper.cpp", directory: "/smallTUReuse", checksumkind: CSK_MD5, checksum: "014145d46991fd1eb6a2192d382feb75")
+!13 = !{!9}
+!14 = !{!"clang version 18.0.0git"}
+!15 = !{i32 7, !"Dwarf Version", i32 5}
+!16 = !{i32 2, !"Debug Info Version", i32 3}
+!17 = !{i32 1, !"wchar_size", i32 4}
+!18 = !{i32 8, !"PIC Level", i32 2}
+!19 = !{i32 7, !"PIE Level", i32 2}
+!20 = !{i32 7, !"uwtable", i32 2}
+!21 = !{i32 7, !"frame-pointer", i32 2}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 41afbea456143..1d9b3d5874756 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -3448,7 +3448,6 @@ uint64_t DwarfDebug::makeTypeSignature(StringRef Identifier) {
 void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
                                       StringRef Identifier, DIE &RefDie,
                                       const DICompositeType *CTy) {
-  setCurrentDWARF5AccelTable(DWARF5AccelTableKind::TU);
   // Fast path if we're building some type units and one has already used the
   // address pool we know we're going to throw away all this work anyway, so
   // don't bother building dependent types.
@@ -3461,6 +3460,7 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
     return;
   }
 
+  setCurrentDWARF5AccelTable(DWARF5AccelTableKind::TU);
   bool TopLevelType = TypeUnitsUnderConstruction.empty();
   AddrPool.resetUsedFlag();
 
@@ -3549,9 +3549,9 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
     AccelTypeUnitsDebugNames.convertDieToOffset();
     AccelDebugNames.addTypeEntries(AccelTypeUnitsDebugNames);
     AccelTypeUnitsDebugNames.clear();
+    setCurrentDWARF5AccelTable(DWARF5AccelTableKind::CU);
   }
   CU.addDIETypeSignature(RefDie, Signature);
-  setCurrentDWARF5AccelTable(DWARF5AccelTableKind::CU);
 }
 
 // Add the Name along with its companion DIE to the appropriate accelerator
@@ -3580,6 +3580,14 @@ void DwarfDebug::addAccelNameImpl(
     break;
   case AccelTableKind::Dwarf: {
     DWARF5AccelTable &Current = getCurrentDWARF5AccelTable();
+    assert((&Current == &AccelTypeUnitsDebugNames) ||
+           ((&Current == &AccelDebugNames) &&
+            (Unit.getUnitDie().getTag() != dwarf::DW_TAG_type_unit)) &&
+               "Kind is CU but TU is being processed.");
+    assert((&Current == &AccelDebugNames) ||
+           ((&Current == &AccelTypeUnitsDebugNames) &&
+            (Unit.getUnitDie().getTag() == dwarf::DW_TAG_type_unit)) &&
+               "Kind is TU but CU is being processed.");
     // The type unit can be discarded, so need to add references to final
     // acceleration table once we know it's complete and we emit it.
     Current.addName(Ref, Die, Unit.getUniqueID());