Index: lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -904,6 +904,42 @@
   return UnderlyingTypeIndex;
 }
 
+/// If this type is derived from a base type then return base type size.
+static uint64_t getBaseTypeSizeInBits(const DITypeRef TyRef) {
+  DIType *Ty = TyRef.resolve();
+  assert(Ty);
+  DIDerivedType *DDTy = dyn_cast<DIDerivedType>(Ty);
+  if (!DDTy)
+    return Ty->getSizeInBits();
+
+  unsigned Tag = DDTy->getTag();
+
+  if (Tag != dwarf::DW_TAG_member && Tag != dwarf::DW_TAG_typedef &&
+    Tag != dwarf::DW_TAG_const_type && Tag != dwarf::DW_TAG_volatile_type &&
+    Tag != dwarf::DW_TAG_restrict_type)
+    return DDTy->getSizeInBits();
+
+  DIType *BaseType = DDTy->getBaseType().resolve();
+
+  // If this type is not derived from any type or the type is a declaration then
+  // take conservative approach.
+  if (!BaseType || BaseType->isForwardDecl())
+    return DDTy->getSizeInBits();
+
+  // If this is a derived type, go ahead and get the base type, unless it's a
+  // reference then it's just the size of the field. Pointer types have no need
+  // of this since they're a different type of qualification on the type.
+  if (BaseType->getTag() == dwarf::DW_TAG_reference_type ||
+    BaseType->getTag() == dwarf::DW_TAG_rvalue_reference_type)
+    return DDTy->getSizeInBits();
+
+  if (DIDerivedType *DT = dyn_cast<DIDerivedType>(BaseType)) {
+    return getBaseTypeSizeInBits(DT);
+  }
+
+  return BaseType->getSizeInBits();
+}
+
 TypeIndex CodeViewDebug::lowerTypeArray(const DICompositeType *Ty) {
   DITypeRef ElementTypeRef = Ty->getBaseType();
   TypeIndex ElementTypeIndex = getTypeIndex(ElementTypeRef);
@@ -911,9 +947,55 @@
   TypeIndex IndexType = Asm->MAI->getPointerSize() == 8
                             ? TypeIndex(SimpleTypeKind::UInt64Quad)
                             : TypeIndex(SimpleTypeKind::UInt32Long);
-  uint64_t Size = Ty->getSizeInBits() / 8;
-  ArrayRecord Record(ElementTypeIndex, IndexType, Size, Ty->getName());
-  return TypeTable.writeArray(Record);
+
+  uint64_t ElementSize = getBaseTypeSizeInBits(ElementTypeRef) / 8;
+
+  bool UndefinedSubrange = false;
+
+  // FIXME:
+  // There is a bug in the front-end where an array of a structure, which was
+  // declared as incomplete structure first, ends up not getting a size assigned
+  // to it. (PR28303)
+  // Example:
+  //   struct A(*p)[3];
+  //   struct A { int f; } a[3];
+  //
+  // This needs to be fixed in the front-end, but in the meantime we don't want
+  // to trigger an assertion because of this.
+  if (Ty->getSizeInBits() == 0) {
+    UndefinedSubrange = true;
+  }
+
+  // Add subranges to array type.
+  DINodeArray Elements = Ty->getElements();
+  for (int i = Elements.size() - 1; i >= 0; --i) {
+    const DINode *Element = Elements[i];
+    assert(Element->getTag() == dwarf::DW_TAG_subrange_type);
+
+    const DISubrange *Subrange = cast<DISubrange>(Element);
+    assert(Subrange->getLowerBound() == 0 &&
+           "codeview doesn't support subranges with lower bounds");
+    int64_t Count = Subrange->getCount();
+
+    // Variable Length Array (VLA) has Count equal to '-1'.
+    // Replace with Count '1', assume it is the minimum VLA length.
+    // FIXME: Make front-end support VLA subrange and emit LF_DIMVARLU.
+    if (Count == -1) {
+      Count = 1;
+      UndefinedSubrange = true;
+    }
+
+    StringRef Name = (i == 0) ? Ty->getName() : "";
+    // Update the element size and element type index for subsequent subranges.
+    ElementSize *= Count;
+    ElementTypeIndex = TypeTable.writeArray(
+        ArrayRecord(ElementTypeIndex, IndexType, ElementSize, Name));
+  }
+
+  (void)UndefinedSubrange;
+  assert(UndefinedSubrange || ElementSize == (Ty->getSizeInBits() / 8));
+
+  return ElementTypeIndex;
 }
 
 TypeIndex CodeViewDebug::lowerTypeBasic(const DIBasicType *Ty) {
Index: test/DebugInfo/COFF/types-array-advanced.ll
===================================================================
--- test/DebugInfo/COFF/types-array-advanced.ll
+++ test/DebugInfo/COFF/types-array-advanced.ll
@@ -0,0 +1,208 @@
+; RUN: llc < %s -filetype=obj | llvm-readobj - -codeview | FileCheck %s
+
+; C++ source to regenerate:
+; $ cat t.cpp
+; char multi_dim_arr[2][5][7];
+;
+; struct incomplete_struct(*p_incomplete_struct_arr)[3];
+; struct incomplete_struct {
+;   int s1;
+; } incomplete_struct_arr[3];
+;
+; void foo(int x) {
+;   int dyn_size_arr[x];
+;   dyn_size_arr[0] = 0;
+; }
+;
+; typedef int T_INT;
+; T_INT typedef_arr[4];
+; $ clang t.cpp -S -emit-llvm -g -gcodeview -o t.ll
+
+; CHECK: CodeViewTypes [
+; CHECK:   Section: .debug$T (5)
+; CHECK:   Magic: 0x4
+; CHECK:   ArgList (0x1000) {
+; CHECK:     TypeLeafKind: LF_ARGLIST (0x1201)
+; CHECK:     NumArgs: 1
+; CHECK:     Arguments [
+; CHECK:       ArgType: int (0x74)
+; CHECK:     ]
+; CHECK:   }
+; CHECK:   Procedure (0x1001) {
+; CHECK:     TypeLeafKind: LF_PROCEDURE (0x1008)
+; CHECK:     ReturnType: void (0x3)
+; CHECK:     CallingConvention: NearC (0x0)
+; CHECK:     FunctionOptions [ (0x0)
+; CHECK:     ]
+; CHECK:     NumParameters: 1
+; CHECK:     ArgListType: (int) (0x1000)
+; CHECK:   }
+; CHECK:   FuncId (0x1002) {
+; CHECK:     TypeLeafKind: LF_FUNC_ID (0x1601)
+; CHECK:     ParentScope: 0x0
+; CHECK:     FunctionType: void (int) (0x1001)
+; CHECK:     Name: foo
+; CHECK:   }
+; CHECK:   Array (0x1003) {
+; CHECK:     TypeLeafKind: LF_ARRAY (0x1503)
+; CHECK:     ElementType: int (0x74)
+; CHECK:     IndexType: unsigned long (0x22)
+; CHECK:     SizeOf: 4
+; CHECK:     Name: 
+; CHECK:   }
+; CHECK:   Array (0x1004) {
+; CHECK:     TypeLeafKind: LF_ARRAY (0x1503)
+; CHECK:     ElementType: char (0x70)
+; CHECK:     IndexType: unsigned long (0x22)
+; CHECK:     SizeOf: 7
+; CHECK:     Name: 
+; CHECK:   }
+; CHECK:   Array (0x1005) {
+; CHECK:     TypeLeafKind: LF_ARRAY (0x1503)
+; CHECK:     ElementType: 0x1004
+; CHECK:     IndexType: unsigned long (0x22)
+; CHECK:     SizeOf: 35
+; CHECK:     Name: 
+; CHECK:   }
+; CHECK:   Array (0x1006) {
+; CHECK:     TypeLeafKind: LF_ARRAY (0x1503)
+; CHECK:     ElementType: 0x1005
+; CHECK:     IndexType: unsigned long (0x22)
+; CHECK:     SizeOf: 70
+; CHECK:     Name: 
+; CHECK:   }
+; CHECK:   Struct (0x1007) {
+; CHECK:     TypeLeafKind: LF_STRUCTURE (0x1505)
+; CHECK:     MemberCount: 0
+; CHECK:     Properties [ (0x280)
+; CHECK:       ForwardReference (0x80)
+; CHECK:       HasUniqueName (0x200)
+; CHECK:     ]
+; CHECK:     FieldList: 0x0
+; CHECK:     DerivedFrom: 0x0
+; CHECK:     VShape: 0x0
+; CHECK:     SizeOf: 0
+; CHECK:     Name: incomplete_struct
+; CHECK:     LinkageName: .?AUincomplete_struct@@
+; CHECK:   }
+; CHECK:   Array (0x1008) {
+; CHECK:     TypeLeafKind: LF_ARRAY (0x1503)
+; CHECK:     ElementType: incomplete_struct (0x1007)
+; CHECK:     IndexType: unsigned long (0x22)
+; CHECK:     SizeOf: 12
+; CHECK:     Name: 
+; CHECK:   }
+; CHECK:   Pointer (0x1009) {
+; CHECK:     TypeLeafKind: LF_POINTER (0x1002)
+; CHECK:     PointeeType: 0x1008
+; CHECK:     PointerAttributes: 0x800A
+; CHECK:     PtrType: Near32 (0xA)
+; CHECK:     PtrMode: Pointer (0x0)
+; CHECK:     IsFlat: 0
+; CHECK:     IsConst: 0
+; CHECK:     IsVolatile: 0
+; CHECK:     IsUnaligned: 0
+; CHECK:     SizeOf: 4
+; CHECK:   }
+;
+; CHECK:   Array (0x100E) {
+; CHECK:     TypeLeafKind: LF_ARRAY (0x1503)
+; CHECK:     ElementType: int (0x74)
+; CHECK:     IndexType: unsigned long (0x22)
+; CHECK:     SizeOf: 16
+; CHECK:     Name:
+; CHECK:   }
+; CHECK: ]
+
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i686-pc-windows-msvc18.0.31101"
+
+%struct.incomplete_struct = type { i32 }
+
+@"\01?multi_dim_arr@@3PAY146DA" = global [2 x [5 x [7 x i8]]] zeroinitializer, align 1
+@"\01?p_incomplete_struct_arr@@3PAY02Uincomplete_struct@@A" = global [3 x i8]* null, align 4
+@"\01?incomplete_struct_arr@@3PAUincomplete_struct@@A" = global [3 x %struct.incomplete_struct] zeroinitializer, align 4
+@"\01?typedef_arr@@3PAHA" = global [4 x i32] zeroinitializer, align 4
+
+; Function Attrs: nounwind
+define void @"\01?foo@@YAXH@Z"(i32 %x) #0 !dbg !29 {
+entry:
+  %x.addr = alloca i32, align 4
+  %saved_stack = alloca i8*, align 4
+  store i32 %x, i32* %x.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %x.addr, metadata !32, metadata !33), !dbg !34
+  %0 = load i32, i32* %x.addr, align 4, !dbg !35
+  %1 = call i8* @llvm.stacksave(), !dbg !36
+  store i8* %1, i8** %saved_stack, align 4, !dbg !36
+  %vla = alloca i32, i32 %0, align 4, !dbg !36
+  call void @llvm.dbg.declare(metadata i32* %vla, metadata !37, metadata !41), !dbg !42
+  %arrayidx = getelementptr inbounds i32, i32* %vla, i32 0, !dbg !43
+  store i32 0, i32* %arrayidx, align 4, !dbg !44
+  %2 = load i8*, i8** %saved_stack, align 4, !dbg !45
+  call void @llvm.stackrestore(i8* %2), !dbg !45
+  ret void, !dbg !45
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: nounwind
+declare i8* @llvm.stacksave() #2
+
+; Function Attrs: nounwind
+declare void @llvm.stackrestore(i8*) #2
+
+attributes #0 = { nounwind }
+attributes #1 = { nounwind readnone }
+attributes #2 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!26, !27}
+!llvm.ident = !{!28}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.9.0 (trunk 273874)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3)
+!1 = !DIFile(filename: "t.cpp", directory: "/")
+!2 = !{}
+!3 = !{!4, !11, !20, !21}
+!4 = distinct !DIGlobalVariable(name: "multi_dim_arr", linkageName: "\01?multi_dim_arr@@3PAY146DA", scope: !0, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, variable: [2 x [5 x [7 x i8]]]* @"\01?multi_dim_arr@@3PAY146DA")
+!5 = !DICompositeType(tag: DW_TAG_array_type, baseType: !6, size: 560, align: 8, elements: !7)
+!6 = !DIBasicType(name: "char", size: 8, align: 8, encoding: DW_ATE_signed_char)
+!7 = !{!8, !9, !10}
+!8 = !DISubrange(count: 2)
+!9 = !DISubrange(count: 5)
+!10 = !DISubrange(count: 7)
+!11 = distinct !DIGlobalVariable(name: "p_incomplete_struct_arr", linkageName: "\01?p_incomplete_struct_arr@@3PAY02Uincomplete_struct@@A", scope: !0, file: !1, line: 3, type: !12, isLocal: false, isDefinition: true, variable: [3 x i8]** @"\01?p_incomplete_struct_arr@@3PAY02Uincomplete_struct@@A")
+!12 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !13, size: 32, align: 32)
+!13 = !DICompositeType(tag: DW_TAG_array_type, baseType: !14, elements: !18)
+!14 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "incomplete_struct", file: !1, line: 4, size: 32, align: 32, elements: !15, identifier: ".?AUincomplete_struct@@")
+!15 = !{!16}
+!16 = !DIDerivedType(tag: DW_TAG_member, name: "s1", scope: !14, file: !1, line: 5, baseType: !17, size: 32, align: 32)
+!17 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!18 = !{!19}
+!19 = !DISubrange(count: 3)
+!20 = distinct !DIGlobalVariable(name: "incomplete_struct_arr", linkageName: "\01?incomplete_struct_arr@@3PAUincomplete_struct@@A", scope: !0, file: !1, line: 6, type: !13, isLocal: false, isDefinition: true, variable: [3 x %struct.incomplete_struct]* @"\01?incomplete_struct_arr@@3PAUincomplete_struct@@A")
+!21 = distinct !DIGlobalVariable(name: "typedef_arr", linkageName: "\01?typedef_arr@@3PAHA", scope: !0, file: !1, line: 14, type: !22, isLocal: false, isDefinition: true, variable: [4 x i32]* @"\01?typedef_arr@@3PAHA")
+!22 = !DICompositeType(tag: DW_TAG_array_type, baseType: !23, size: 128, align: 32, elements: !24)
+!23 = !DIDerivedType(tag: DW_TAG_typedef, name: "T_INT", file: !1, line: 13, baseType: !17)
+!24 = !{!25}
+!25 = !DISubrange(count: 4)
+!26 = !{i32 2, !"CodeView", i32 1}
+!27 = !{i32 2, !"Debug Info Version", i32 3}
+!28 = !{!"clang version 3.9.0 (trunk 273874)"}
+!29 = distinct !DISubprogram(name: "foo", linkageName: "\01?foo@@YAXH@Z", scope: !1, file: !1, line: 8, type: !30, isLocal: false, isDefinition: true, scopeLine: 8, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!30 = !DISubroutineType(types: !31)
+!31 = !{null, !17}
+!32 = !DILocalVariable(name: "x", arg: 1, scope: !29, file: !1, line: 8, type: !17)
+!33 = !DIExpression()
+!34 = !DILocation(line: 8, column: 14, scope: !29)
+!35 = !DILocation(line: 9, column: 21, scope: !29)
+!36 = !DILocation(line: 9, column: 4, scope: !29)
+!37 = !DILocalVariable(name: "dyn_size_arr", scope: !29, file: !1, line: 9, type: !38)
+!38 = !DICompositeType(tag: DW_TAG_array_type, baseType: !17, align: 32, elements: !39)
+!39 = !{!40}
+!40 = !DISubrange(count: -1)
+!41 = !DIExpression(DW_OP_deref)
+!42 = !DILocation(line: 9, column: 8, scope: !29)
+!43 = !DILocation(line: 10, column: 4, scope: !29)
+!44 = !DILocation(line: 10, column: 20, scope: !29)
+!45 = !DILocation(line: 11, column: 1, scope: !29)