Index: lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -1814,12 +1814,33 @@
     Info.Members.push_back({DDTy, 0});
     return;
   }
-  // An unnamed member must represent a nested struct or union. Add all the
-  // indirect fields to the current record.
+
+  // An unnamed member may represent a nested struct or union. Attempt to
+  // interpret the unnamed member as a DICompositeType possibly wrapped in
+  // qualifier types. Add all the indirect fields to the current record if that
+  // succeeds, and drop the member if that fails.
   assert((DDTy->getOffsetInBits() % 8) == 0 && "Unnamed bitfield member!");
   uint64_t Offset = DDTy->getOffsetInBits();
   const DIType *Ty = DDTy->getBaseType().resolve();
-  const DICompositeType *DCTy = cast<DICompositeType>(Ty);
+  bool FullyResolved = false;
+  while (!FullyResolved) {
+    switch (Ty->getTag()) {
+    case dwarf::DW_TAG_const_type:
+    case dwarf::DW_TAG_volatile_type:
+      // FIXME: we should apply the qualifier types to the indirect fields
+      // rather than dropping them.
+      Ty = cast<DIDerivedType>(Ty)->getBaseType().resolve();
+      break;
+    default:
+      FullyResolved = true;
+      break;
+    }
+  }
+
+  const DICompositeType *DCTy = dyn_cast<DICompositeType>(Ty);
+  if (!DCTy)
+    return;
+
   ClassInfo NestedInfo = collectClassInfo(DCTy);
   for (const ClassInfo::MemberInfo &IndirectField : NestedInfo.Members)
     Info.Members.push_back(
Index: test/DebugInfo/COFF/const-unnamed-member.ll
===================================================================
--- /dev/null
+++ test/DebugInfo/COFF/const-unnamed-member.ll
@@ -0,0 +1,61 @@
+; RUN: llc -filetype=obj < %s | llvm-readobj -codeview - | FileCheck %s
+
+; Objective-C++ source demonstrating the issue:
+; void (^b)(void) = []() {};
+
+; C++ source derived and modified from:
+; struct S {
+;   struct {
+;     int a;
+;   };
+; } s;
+
+; CHECK: CodeViewTypes [
+; CHECK:  FieldList ([[S_fl:.*]]) {
+; CHECK:    TypeLeafKind: LF_FIELDLIST (0x1203)
+; CHECK:    DataMember {
+; CHECK:      Type: int (0x74)
+; CHECK:      FieldOffset: 0x0
+; CHECK:      Name: a
+; CHECK:    }
+; CHECK:  }
+; CHECK:  Struct ({{.*}}) {
+; CHECK:    TypeLeafKind: LF_STRUCTURE (0x1505)
+; CHECK:    MemberCount: 2
+; CHECK:    FieldList: <field list> ([[S_fl]])
+; CHECK:    SizeOf: 4
+; CHECK:    Name: S
+; CHECK:    LinkageName: .?AUS@@
+; CHECK:  }
+
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i686--windows-msvc19.11.0"
+
+%struct.S = type { %struct.anon }
+%struct.anon = type { i32 }
+
+@"\01?s@@3US@@A" = dso_local global %struct.S zeroinitializer, align 4, !dbg !0
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!13, !14, !15, !16}
+!llvm.ident = !{!17}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "s", linkageName: "\01?s@@3US@@A", scope: !2, file: !3, line: 5, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "clang version 7.0.0 (trunk 325940) (llvm/trunk 325939)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
+!3 = !DIFile(filename: "/tmp/ugh.cpp", directory: "/home/smeenai/llvm/build/llvm/Debug", checksumkind: CSK_MD5, checksum: "8256b51d95df0b5e42b848a3afe9cbda")
+!4 = !{}
+!5 = !{!0}
+!6 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S", file: !3, line: 1, size: 32, flags: DIFlagTypePassByValue, elements: !7, identifier: ".?AUS@@")
+!7 = !{!8, !12}
+!8 = distinct !DICompositeType(tag: DW_TAG_structure_type, scope: !6, file: !3, line: 2, size: 32, flags: DIFlagTypePassByValue, elements: !9, identifier: ".?AU<unnamed-type-$S1>@S@@")
+!9 = !{!10}
+!10 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !8, file: !3, line: 3, baseType: !11, size: 32)
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !DIDerivedType(tag: DW_TAG_member, scope: !6, file: !3, line: 2, baseType: !18, size: 32) ; !8 changed to !18
+!13 = !{i32 1, !"NumRegisterParameters", i32 0}
+!14 = !{i32 2, !"CodeView", i32 1}
+!15 = !{i32 2, !"Debug Info Version", i32 3}
+!16 = !{i32 1, !"wchar_size", i32 2}
+!17 = !{!"clang version 7.0.0 (trunk 325940) (llvm/trunk 325939)"}
+!18 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !8) ; added manually