Index: include/lldb/Symbol/ClangASTContext.h
===================================================================
--- include/lldb/Symbol/ClangASTContext.h
+++ include/lldb/Symbol/ClangASTContext.h
@@ -831,6 +831,8 @@
                            bool is_static, bool is_inline, bool is_explicit,
                            bool is_attr_used, bool is_artificial);
 
+  void AddMethodOverridesForCXXRecordType(lldb::opaque_compiler_type_t type);
+
   // C++ Base Classes
   clang::CXXBaseSpecifier *
   CreateBaseClassSpecifier(lldb::opaque_compiler_type_t type,
Index: lit/SymbolFile/PDB/Inputs/UdtCompletionTest.cpp
===================================================================
--- /dev/null
+++ lit/SymbolFile/PDB/Inputs/UdtCompletionTest.cpp
@@ -0,0 +1,61 @@
+union U {
+  char _u1;
+  short _u2;
+  int _u3;
+};
+
+struct A {
+  explicit A(int u) { _u._u3 = u; }
+  A(const A &) = default;
+  virtual ~A() = default;
+
+private:
+  U _u;
+};
+
+#pragma pack(push, 1)
+struct B : public virtual A {
+  B(char a, char b, char c) : A(a + b + c), _a(a), _b(b), _c(c) {}
+  B(const B &) = default;
+
+private:
+  char _a;
+  unsigned short : 3;
+  unsigned short _b : 6;
+  unsigned short : 4;
+  int _c;
+};
+#pragma pack(pop)
+
+#pragma pack(push, 16)
+class C : public virtual A, private B {
+public:
+  C(char x, char y, char z)
+      : A(x - y + z), B(x, y, z), _x(x * 2), _y(y * 2), _z(z * 2) {}
+  C(const C &) = default;
+
+  static int abc;
+
+private:
+  int _x;
+  short _y;
+  char _z;
+};
+int C::abc = 123;
+#pragma pack(pop)
+
+class List {
+public:
+  List(List *p, List *n, C v) : Prev(p), Next(n), Value(v) {}
+
+private:
+  List *Prev;
+  List *Next;
+  C Value;
+};
+
+int main(int argc, char *argv[]) {
+  List l{nullptr, nullptr, C{1, 2, 3}};
+
+  return 0;
+}
Index: lit/SymbolFile/PDB/Inputs/UdtCompletionTest.script
===================================================================
--- /dev/null
+++ lit/SymbolFile/PDB/Inputs/UdtCompletionTest.script
@@ -0,0 +1,4 @@
+breakpoint set --file UdtCompletionTest.cpp --line 60
+run
+target variable
+frame variable
Index: lit/SymbolFile/PDB/udt-completion.test
===================================================================
--- /dev/null
+++ lit/SymbolFile/PDB/udt-completion.test
@@ -0,0 +1,26 @@
+REQUIRES: windows
+RUN: clang-cl /Zi %S/Inputs/UdtCompletionTest.cpp /o %t.exe
+RUN: %lldb -b -s %S/Inputs/UdtCompletionTest.script -- %t.exe | FileCheck %s
+
+CHECK: (int) int C::abc = 123
+
+CHECK: (List) l = {
+CHECK:   Prev = 0x00000000
+CHECK:   Next = 0x00000000
+CHECK:   Value = {
+CHECK:     A = {
+CHECK:       _u = (_u1 = '\x02', _u2 = 2, _u3 = 2)
+CHECK:     }
+CHECK:     B = {
+CHECK:       A = {
+CHECK:         _u = (_u1 = '\x02', _u2 = 2, _u3 = 2)
+CHECK:       }
+CHECK:       _a = '\x01'
+CHECK:       _b = 2
+CHECK:       _c = 3
+CHECK:     }
+CHECK:     _x = 2
+CHECK:     _y = 4
+CHECK:     _z = '\x06'
+CHECK:   }
+CHECK: }
Index: source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
===================================================================
--- source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -2108,95 +2108,6 @@
   return template_param_infos.args.size() == template_param_infos.names.size();
 }
 
-// Checks whether m1 is an overload of m2 (as opposed to an override). This is
-// called by addOverridesForMethod to distinguish overrides (which share a
-// vtable entry) from overloads (which require distinct entries).
-static bool isOverload(clang::CXXMethodDecl *m1, clang::CXXMethodDecl *m2) {
-  // FIXME: This should detect covariant return types, but currently doesn't.
-  lldbassert(&m1->getASTContext() == &m2->getASTContext() &&
-             "Methods should have the same AST context");
-  clang::ASTContext &context = m1->getASTContext();
-
-  const auto *m1Type =
-    llvm::cast<clang::FunctionProtoType>(
-      context.getCanonicalType(m1->getType()));
-
-  const auto *m2Type =
-    llvm::cast<clang::FunctionProtoType>(
-      context.getCanonicalType(m2->getType()));
-
-  auto compareArgTypes =
-    [&context](const clang::QualType &m1p, const clang::QualType &m2p) {
-      return context.hasSameType(m1p.getUnqualifiedType(),
-                                 m2p.getUnqualifiedType());
-    };
-
-  // FIXME: In C++14 and later, we can just pass m2Type->param_type_end()
-  //        as a fourth parameter to std::equal().
-  return (m1->getNumParams() != m2->getNumParams()) ||
-         !std::equal(m1Type->param_type_begin(), m1Type->param_type_end(),
-                     m2Type->param_type_begin(), compareArgTypes);
-}
-
-// If decl is a virtual method, walk the base classes looking for methods that
-// decl overrides. This table of overridden methods is used by IRGen to
-// determine the vtable layout for decl's parent class.
-static void addOverridesForMethod(clang::CXXMethodDecl *decl) {
-  if (!decl->isVirtual())
-    return;
-
-  clang::CXXBasePaths paths;
-
-  auto find_overridden_methods =
-    [decl](const clang::CXXBaseSpecifier *specifier, clang::CXXBasePath &path) {
-      if (auto *base_record =
-          llvm::dyn_cast<clang::CXXRecordDecl>(
-            specifier->getType()->getAs<clang::RecordType>()->getDecl())) {
-
-        clang::DeclarationName name = decl->getDeclName();
-
-        // If this is a destructor, check whether the base class destructor is
-        // virtual.
-        if (name.getNameKind() == clang::DeclarationName::CXXDestructorName)
-          if (auto *baseDtorDecl = base_record->getDestructor()) {
-            if (baseDtorDecl->isVirtual()) {
-              path.Decls = baseDtorDecl;
-              return true;
-            } else
-              return false;
-          }
-
-        // Otherwise, search for name in the base class.
-        for (path.Decls = base_record->lookup(name); !path.Decls.empty();
-             path.Decls = path.Decls.slice(1)) {
-          if (auto *method_decl =
-                llvm::dyn_cast<clang::CXXMethodDecl>(path.Decls.front()))
-            if (method_decl->isVirtual() && !isOverload(decl, method_decl)) {
-              path.Decls = method_decl;
-              return true;
-            }
-        }
-      }
-
-      return false;
-    };
-
-  if (decl->getParent()->lookupInBases(find_overridden_methods, paths)) {
-    for (auto *overridden_decl : paths.found_decls())
-      decl->addOverriddenMethod(
-        llvm::cast<clang::CXXMethodDecl>(overridden_decl));
-  }
-}
-
-// If clang_type is a CXXRecordDecl, builds the method override list for each
-// of its virtual methods.
-static void addMethodOverrides(ClangASTContext &ast, CompilerType &clang_type) {
-  if (auto *record =
-      ast.GetAsCXXRecordDecl(clang_type.GetOpaqueQualType()))
-    for (auto *method : record->methods())
-      addOverridesForMethod(method);
-}
-
 bool DWARFASTParserClang::CompleteTypeFromDWARF(const DWARFDIE &die,
                                                 lldb_private::Type *type,
                                                 CompilerType &clang_type) {
@@ -2405,7 +2316,7 @@
       }
     }
 
-    addMethodOverrides(m_ast, clang_type);
+    m_ast.AddMethodOverridesForCXXRecordType(clang_type.GetOpaqueQualType());
     ClangASTContext::BuildIndirectFields(clang_type);
     ClangASTContext::CompleteTagDeclarationDefinition(clang_type);
 
Index: source/Plugins/SymbolFile/PDB/PDBASTParser.h
===================================================================
--- source/Plugins/SymbolFile/PDB/PDBASTParser.h
+++ source/Plugins/SymbolFile/PDB/PDBASTParser.h
@@ -28,9 +28,13 @@
 
 namespace llvm {
 namespace pdb {
+template <typename ChildType> class ConcreteSymbolEnumerator;
+
 class PDBSymbol;
 class PDBSymbolData;
+class PDBSymbolTypeBaseClass;
 class PDBSymbolTypeBuiltin;
+class PDBSymbolTypeUDT;
 } // namespace pdb
 } // namespace llvm
 
@@ -40,13 +44,40 @@
   ~PDBASTParser();
 
   lldb::TypeSP CreateLLDBTypeFromPDBType(const llvm::pdb::PDBSymbol &type);
+  bool CompleteTypeFromPDB(lldb_private::CompilerType &compiler_type);
+
+  lldb_private::ClangASTImporter &GetClangASTImporter() {
+    return m_ast_importer;
+  }
 
 private:
+  typedef llvm::DenseMap<lldb::opaque_compiler_type_t, lldb::user_id_t>
+      ClangTypeToUidMap;
+  typedef llvm::pdb::ConcreteSymbolEnumerator<llvm::pdb::PDBSymbolData>
+      PDBDataSymbolEnumerator;
+  typedef llvm::pdb::ConcreteSymbolEnumerator<llvm::pdb::PDBSymbolTypeBaseClass>
+      PDBBaseClassSymbolEnumerator;
+
   bool AddEnumValue(lldb_private::CompilerType enum_type,
                     const llvm::pdb::PDBSymbolData &data) const;
+  bool CompleteTypeFromUDT(lldb_private::SymbolFile &symbol_file,
+                           lldb_private::CompilerType &compiler_type,
+                           llvm::pdb::PDBSymbolTypeUDT &udt);
+  void AddRecordMembers(
+      lldb_private::SymbolFile &symbol_file,
+      lldb_private::CompilerType &record_type,
+      PDBDataSymbolEnumerator &members_enum,
+      lldb_private::ClangASTImporter::LayoutInfo &layout_info) const;
+  void AddRecordBases(
+      lldb_private::SymbolFile &symbol_file,
+      lldb_private::CompilerType &record_type,
+      int record_kind,
+      PDBBaseClassSymbolEnumerator &bases_enum,
+      lldb_private::ClangASTImporter::LayoutInfo &layout_info) const;
 
   lldb_private::ClangASTContext &m_ast;
   lldb_private::ClangASTImporter m_ast_importer;
+  ClangTypeToUidMap m_forward_decl_clang_type_to_uid;
 };
 
 #endif // LLDB_PLUGINS_SYMBOLFILE_PDB_PDBASTPARSER_H
Index: source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
===================================================================
--- source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
+++ source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
@@ -9,10 +9,13 @@
 
 #include "PDBASTParser.h"
 
+#include "SymbolFilePDB.h"
+
 #include "clang/AST/CharUnits.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclCXX.h"
 
+#include "lldb/Core/Module.h"
 #include "lldb/Symbol/ClangASTContext.h"
 #include "lldb/Symbol/ClangUtil.h"
 #include "lldb/Symbol/Declaration.h"
@@ -199,6 +202,19 @@
   decl.SetLine(first_line_up->getLineNumber());
   return true;
 }
+
+AccessType TranslateUdtAccess(PDB_MemberAccess access) {
+  switch (access) {
+  case PDB_MemberAccess::Private:
+    return eAccessPrivate;
+  case PDB_MemberAccess::Protected:
+    return eAccessProtected;
+  case PDB_MemberAccess::Public:
+    return eAccessPublic;
+  default:
+    return eAccessNone;
+  }
+}
 } // namespace
 
 PDBASTParser::PDBASTParser(lldb_private::ClangASTContext &ast) : m_ast(ast) {}
@@ -232,10 +248,17 @@
         tu_decl_ctx, access, udt->getName().c_str(), tag_type_kind,
         lldb::eLanguageTypeC_plus_plus, nullptr);
 
+    ClangASTContext::StartTagDeclarationDefinition(clang_type);
+
+    auto clang_type_removed_fast_quals =
+        ClangUtil::RemoveFastQualifiers(clang_type).GetOpaqueQualType();
+    auto sym_uid = type.getSymIndexId();
+    m_forward_decl_clang_type_to_uid[clang_type_removed_fast_quals] = sym_uid;
+
     m_ast.SetHasExternalStorage(clang_type.GetOpaqueQualType(), true);
 
     return std::make_shared<lldb_private::Type>(
-        type.getSymIndexId(), m_ast.GetSymbolFile(),
+        sym_uid, m_ast.GetSymbolFile(),
         ConstString(udt->getName()), udt->getLength(), nullptr,
         LLDB_INVALID_UID, lldb_private::Type::eEncodingIsUID, decl, clang_type,
         lldb_private::Type::eResolveStateForward);
@@ -471,6 +494,46 @@
   return nullptr;
 }
 
+bool PDBASTParser::CompleteTypeFromPDB(
+    lldb_private::CompilerType &compiler_type) {
+  if (GetClangASTImporter().CanImport(compiler_type))
+    return GetClangASTImporter().CompleteType(compiler_type);
+
+  CompilerType compiler_type_no_qualifiers =
+      ClangUtil::RemoveFastQualifiers(compiler_type);
+  auto uid_it = m_forward_decl_clang_type_to_uid.find(
+      compiler_type_no_qualifiers.GetOpaqueQualType());
+  if (uid_it == m_forward_decl_clang_type_to_uid.end())
+    return true;
+
+  auto symbol_file = static_cast<SymbolFilePDB *>(m_ast.GetSymbolFile());
+  if (!symbol_file)
+    return false;
+
+  std::unique_ptr<PDBSymbol> symbol =
+      symbol_file->GetPDBSession().getSymbolById(uid_it->getSecond());
+  if (!symbol)
+    return false;
+
+  m_forward_decl_clang_type_to_uid.erase(uid_it);
+
+  ClangASTContext::SetHasExternalStorage(compiler_type.GetOpaqueQualType(),
+                                         false);
+
+  switch (symbol->getSymTag()) {
+  case PDB_SymType::UDT: {
+    auto udt = llvm::dyn_cast<PDBSymbolTypeUDT>(symbol.get());
+    if (!udt)
+      return false;
+
+    return CompleteTypeFromUDT(*symbol_file, compiler_type, *udt);
+  }
+  default:
+    assert(false && "not a forward clang type decl!");
+    return false;
+  }
+}
+
 bool PDBASTParser::AddEnumValue(CompilerType enum_type,
                                 const PDBSymbolData &enum_value) const {
   Declaration decl;
@@ -513,3 +576,142 @@
       enum_type.GetOpaqueQualType(), underlying_type, decl, name.c_str(),
       raw_value, byte_size * 8);
 }
+
+bool PDBASTParser::CompleteTypeFromUDT(
+    lldb_private::SymbolFile &symbol_file,
+    lldb_private::CompilerType &compiler_type,
+    llvm::pdb::PDBSymbolTypeUDT &udt) {
+  ClangASTImporter::LayoutInfo layout_info;
+  layout_info.bit_size = udt.getLength() * 8;
+
+  auto kind = TranslateUdtKind(udt.getUdtKind());
+  if (kind == -1)
+    kind = clang::TTK_Class;
+  m_ast.SetTagTypeKind(ClangUtil::GetQualType(compiler_type), kind);
+
+  auto members_enum = udt.findAllChildren<PDBSymbolData>();
+  if (members_enum)
+    AddRecordMembers(symbol_file, compiler_type, *members_enum, layout_info);
+
+  auto bases_enum = udt.findAllChildren<PDBSymbolTypeBaseClass>();
+  if (bases_enum)
+    AddRecordBases(symbol_file, compiler_type, kind, *bases_enum, layout_info);
+
+  m_ast.AddMethodOverridesForCXXRecordType(compiler_type.GetOpaqueQualType());
+  ClangASTContext::BuildIndirectFields(compiler_type);
+  ClangASTContext::CompleteTagDeclarationDefinition(compiler_type);
+
+  clang::CXXRecordDecl *record_decl =
+      m_ast.GetAsCXXRecordDecl(compiler_type.GetOpaqueQualType());
+  if (!record_decl)
+    return static_cast<bool>(compiler_type);
+
+  GetClangASTImporter().InsertRecordDecl(record_decl, layout_info);
+
+  return static_cast<bool>(compiler_type);
+}
+
+void PDBASTParser::AddRecordMembers(
+    lldb_private::SymbolFile &symbol_file,
+    lldb_private::CompilerType &record_type,
+    PDBDataSymbolEnumerator &members_enum,
+    lldb_private::ClangASTImporter::LayoutInfo &layout_info) const {
+  while (auto member = members_enum.getNext()) {
+    auto member_name = member->getName();
+
+    auto member_type = symbol_file.ResolveTypeUID(member->getTypeId());
+    if (!member_type)
+      continue;
+
+    auto member_comp_type = member_type->GetLayoutCompilerType();
+    if (!member_comp_type.GetCompleteType()) {
+      symbol_file.GetObjectFile()->GetModule()->ReportError(
+          ":: Class '%s' has a member '%s' of type '%s' "
+          "which does not have a complete definition.",
+          record_type.GetTypeName().GetCString(), member_name.c_str(),
+          member_comp_type.GetTypeName().GetCString());
+      if (ClangASTContext::StartTagDeclarationDefinition(member_comp_type))
+        ClangASTContext::CompleteTagDeclarationDefinition(member_comp_type);
+    }
+
+    auto access = TranslateUdtAccess(member->getAccess());
+    if (access == eAccessNone)
+      access = eAccessPublic;
+
+    auto location_type = member->getLocationType();
+    if (location_type == PDB_LocType::ThisRel ||
+        location_type == PDB_LocType::BitField) {
+      auto bit_size = member->getLength();
+      if (location_type == PDB_LocType::ThisRel)
+        bit_size *= 8;
+
+      auto decl = ClangASTContext::AddFieldToRecordType(
+          record_type, member_name.c_str(), member_comp_type, access, bit_size);
+      if (!decl)
+        continue;
+
+      auto offset = member->getOffset() * 8;
+      if (location_type == PDB_LocType::BitField)
+        offset += member->getBitPosition();
+
+      layout_info.field_offsets.insert(std::make_pair(decl, offset));
+    } else
+      ClangASTContext::AddVariableToRecordType(record_type, member_name.c_str(),
+                                               member_comp_type, access);
+  }
+}
+
+void PDBASTParser::AddRecordBases(
+    lldb_private::SymbolFile &symbol_file,
+    lldb_private::CompilerType &record_type, int record_kind,
+    PDBBaseClassSymbolEnumerator &bases_enum,
+    lldb_private::ClangASTImporter::LayoutInfo &layout_info) const {
+  std::vector<clang::CXXBaseSpecifier *> base_classes;
+  while (auto base = bases_enum.getNext()) {
+    auto base_type = symbol_file.ResolveTypeUID(base->getTypeId());
+    if (!base_type)
+      continue;
+
+    auto base_comp_type = base_type->GetLayoutCompilerType();
+    if (!base_comp_type.GetCompleteType()) {
+      symbol_file.GetObjectFile()->GetModule()->ReportError(
+          ":: Class '%s' has a base class '%s' "
+          "which does not have a complete definition.",
+          record_type.GetTypeName().GetCString(),
+          base_comp_type.GetTypeName().GetCString());
+      if (ClangASTContext::StartTagDeclarationDefinition(base_comp_type))
+        ClangASTContext::CompleteTagDeclarationDefinition(base_comp_type);
+    }
+
+    auto access = TranslateUdtAccess(base->getAccess());
+    if (access == eAccessNone)
+      access = eAccessPublic;
+
+    auto is_virtual = base->isVirtualBaseClass();
+
+    auto base_class_spec = m_ast.CreateBaseClassSpecifier(
+        base_comp_type.GetOpaqueQualType(), access, is_virtual,
+        record_kind == clang::TTK_Class);
+    if (!base_class_spec)
+        continue;
+
+    base_classes.push_back(base_class_spec);
+
+    if (is_virtual)
+        continue;
+
+    auto decl = m_ast.GetAsCXXRecordDecl(base_comp_type.GetOpaqueQualType());
+    if (!decl)
+      continue;
+
+    auto offset = clang::CharUnits::fromQuantity(base->getOffset());
+    layout_info.base_offsets.insert(std::make_pair(decl, offset));
+  }
+  if (!base_classes.empty()) {
+    m_ast.SetBaseClassesForClassType(record_type.GetOpaqueQualType(),
+                                     &base_classes.front(),
+                                     base_classes.size());
+    ClangASTContext::DeleteBaseClassSpecifiers(&base_classes.front(),
+                                               base_classes.size());
+  }
+}
Index: source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
===================================================================
--- source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
+++ source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
@@ -459,10 +459,13 @@
 
         // This should cause the type to get cached and stored in the `m_types`
         // lookup.
-        if (!ResolveTypeUID(symbol->getSymIndexId()))
-          continue;
-
-        ++num_added;
+        if (auto type = ResolveTypeUID(symbol->getSymIndexId())) {
+          // Resolve the type completely to avoid a completion
+          // (and so a list change, which causes an iterators invalidation)
+          // during a TypeList dumping
+          type->GetFullCompilerType();
+          ++num_added;
+        }
       }
     }
   };
@@ -568,8 +571,20 @@
 }
 
 bool SymbolFilePDB::CompleteType(lldb_private::CompilerType &compiler_type) {
-  // TODO: Implement this
-  return false;
+  std::lock_guard<std::recursive_mutex> guard(
+      GetObjectFile()->GetModule()->GetMutex());
+
+  ClangASTContext *clang_ast_ctx = llvm::dyn_cast_or_null<ClangASTContext>(
+      GetTypeSystemForLanguage(lldb::eLanguageTypeC_plus_plus));
+  if (!clang_ast_ctx)
+    return false;
+
+  PDBASTParser *pdb =
+      llvm::dyn_cast<PDBASTParser>(clang_ast_ctx->GetPDBParser());
+  if (!pdb)
+    return false;
+
+  return pdb->CompleteTypeFromPDB(compiler_type);
 }
 
 lldb_private::CompilerDecl SymbolFilePDB::GetDeclForUID(lldb::user_id_t uid) {
Index: source/Symbol/ClangASTContext.cpp
===================================================================
--- source/Symbol/ClangASTContext.cpp
+++ source/Symbol/ClangASTContext.cpp
@@ -124,6 +124,84 @@
          // Use Clang for D until there is a proper language plugin for it
          language == eLanguageTypeD;
 }
+
+// Checks whether m1 is an overload of m2 (as opposed to an override). This is
+// called by addOverridesForMethod to distinguish overrides (which share a
+// vtable entry) from overloads (which require distinct entries).
+bool isOverload(clang::CXXMethodDecl *m1, clang::CXXMethodDecl *m2) {
+  // FIXME: This should detect covariant return types, but currently doesn't.
+  lldbassert(&m1->getASTContext() == &m2->getASTContext() &&
+             "Methods should have the same AST context");
+  clang::ASTContext &context = m1->getASTContext();
+
+  const auto *m1Type = llvm::cast<clang::FunctionProtoType>(
+      context.getCanonicalType(m1->getType()));
+
+  const auto *m2Type = llvm::cast<clang::FunctionProtoType>(
+      context.getCanonicalType(m2->getType()));
+
+  auto compareArgTypes = [&context](const clang::QualType &m1p,
+                                    const clang::QualType &m2p) {
+    return context.hasSameType(m1p.getUnqualifiedType(),
+                               m2p.getUnqualifiedType());
+  };
+
+  // FIXME: In C++14 and later, we can just pass m2Type->param_type_end()
+  //        as a fourth parameter to std::equal().
+  return (m1->getNumParams() != m2->getNumParams()) ||
+         !std::equal(m1Type->param_type_begin(), m1Type->param_type_end(),
+                     m2Type->param_type_begin(), compareArgTypes);
+}
+
+// If decl is a virtual method, walk the base classes looking for methods that
+// decl overrides. This table of overridden methods is used by IRGen to
+// determine the vtable layout for decl's parent class.
+void addOverridesForMethod(clang::CXXMethodDecl *decl) {
+  if (!decl->isVirtual())
+    return;
+
+  clang::CXXBasePaths paths;
+
+  auto find_overridden_methods =
+      [decl](const clang::CXXBaseSpecifier *specifier,
+             clang::CXXBasePath &path) {
+        if (auto *base_record = llvm::dyn_cast<clang::CXXRecordDecl>(
+                specifier->getType()->getAs<clang::RecordType>()->getDecl())) {
+
+          clang::DeclarationName name = decl->getDeclName();
+
+          // If this is a destructor, check whether the base class destructor is
+          // virtual.
+          if (name.getNameKind() == clang::DeclarationName::CXXDestructorName)
+            if (auto *baseDtorDecl = base_record->getDestructor()) {
+              if (baseDtorDecl->isVirtual()) {
+                path.Decls = baseDtorDecl;
+                return true;
+              } else
+                return false;
+            }
+
+          // Otherwise, search for name in the base class.
+          for (path.Decls = base_record->lookup(name); !path.Decls.empty();
+               path.Decls = path.Decls.slice(1)) {
+            if (auto *method_decl =
+                    llvm::dyn_cast<clang::CXXMethodDecl>(path.Decls.front()))
+              if (method_decl->isVirtual() && !isOverload(decl, method_decl)) {
+                path.Decls = method_decl;
+                return true;
+              }
+          }
+        }
+
+        return false;
+      };
+
+  if (decl->getParent()->lookupInBases(find_overridden_methods, paths)) {
+    for (auto *overridden_decl : paths.found_decls())
+      decl->addOverriddenMethod(
+          llvm::cast<clang::CXXMethodDecl>(overridden_decl));
+  }
+}
 }
 
 typedef lldb_private::ThreadSafeDenseMap<clang::ASTContext *, ClangASTContext *>
@@ -8125,6 +8203,13 @@
   return cxx_method_decl;
 }
 
+void ClangASTContext::AddMethodOverridesForCXXRecordType(
+    lldb::opaque_compiler_type_t type) {
+  if (auto *record = GetAsCXXRecordDecl(type))
+    for (auto *method : record->methods())
+      addOverridesForMethod(method);
+}
+
 #pragma mark C++ Base Classes
 
 clang::CXXBaseSpecifier *
@@ -9664,11 +9749,16 @@
     llvm::DenseMap<const clang::CXXRecordDecl *, clang::CharUnits>
         &vbase_offsets) {
   ClangASTContext *ast = (ClangASTContext *)baton;
-  DWARFASTParserClang *dwarf_ast_parser =
-      (DWARFASTParserClang *)ast->GetDWARFParser();
-  return dwarf_ast_parser->GetClangASTImporter().LayoutRecordType(
-      record_decl, bit_size, alignment, field_offsets, base_offsets,
-      vbase_offsets);
+  lldb_private::ClangASTImporter *importer = nullptr;
+  if (ast->m_dwarf_ast_parser_ap)
+    importer = &ast->m_dwarf_ast_parser_ap->GetClangASTImporter();
+  if (!importer && ast->m_pdb_ast_parser_ap)
+    importer = &ast->m_pdb_ast_parser_ap->GetClangASTImporter();
+  if (!importer)
+    return false;
+
+  return importer->LayoutRecordType(record_decl, bit_size, alignment,
+                                    field_offsets, base_offsets, vbase_offsets);
 }
 
 //----------------------------------------------------------------------