diff --git a/tools/aapt2/Resource.cpp b/tools/aapt2/Resource.cpp
index b78f48c..6364ccd 100644
--- a/tools/aapt2/Resource.cpp
+++ b/tools/aapt2/Resource.cpp
@@ -78,6 +78,8 @@
       return "interpolator";
     case ResourceType::kLayout:
       return "layout";
+    case ResourceType::kMacro:
+      return "macro";
     case ResourceType::kMenu:
       return "menu";
     case ResourceType::kMipmap:
@@ -119,6 +121,7 @@
     {"integer", ResourceType::kInteger},
     {"interpolator", ResourceType::kInterpolator},
     {"layout", ResourceType::kLayout},
+    {"macro", ResourceType::kMacro},
     {"menu", ResourceType::kMenu},
     {"mipmap", ResourceType::kMipmap},
     {"navigation", ResourceType::kNavigation},
diff --git a/tools/aapt2/Resource.h b/tools/aapt2/Resource.h
index cf93870..307c21d 100644
--- a/tools/aapt2/Resource.h
+++ b/tools/aapt2/Resource.h
@@ -57,6 +57,7 @@
   kInteger,
   kInterpolator,
   kLayout,
+  kMacro,
   kMenu,
   kMipmap,
   kNavigation,
diff --git a/tools/aapt2/ResourceParser.cpp b/tools/aapt2/ResourceParser.cpp
index 24c60b7..1efabbb 100644
--- a/tools/aapt2/ResourceParser.cpp
+++ b/tools/aapt2/ResourceParser.cpp
@@ -627,6 +627,16 @@
     }
 
     return true;
+  } else if (resource_type == "macro") {
+    if (!maybe_name) {
+      diag_->Error(DiagMessage(out_resource->source)
+                   << "<" << parser->element_name() << "> missing 'name' attribute");
+      return false;
+    }
+
+    out_resource->name.type = ResourceType::kMacro;
+    out_resource->name.entry = maybe_name.value().to_string();
+    return ParseMacro(parser, out_resource);
   }
 
   if (can_be_item) {
@@ -726,16 +736,8 @@
   return true;
 }
 
-/**
- * Reads the entire XML subtree and attempts to parse it as some Item,
- * with typeMask denoting which items it can be. If allowRawValue is
- * true, a RawString is returned if the XML couldn't be parsed as
- * an Item. If allowRawValue is false, nullptr is returned in this
- * case.
- */
-std::unique_ptr<Item> ResourceParser::ParseXml(xml::XmlPullParser* parser,
-                                               const uint32_t type_mask,
-                                               const bool allow_raw_value) {
+std::optional<FlattenedXmlSubTree> ResourceParser::CreateFlattenSubTree(
+    xml::XmlPullParser* parser) {
   const size_t begin_xml_line = parser->line_number();
 
   std::string raw_value;
@@ -745,30 +747,60 @@
     return {};
   }
 
-  if (!style_string.spans.empty()) {
+  return FlattenedXmlSubTree{.raw_value = raw_value,
+                             .style_string = style_string,
+                             .untranslatable_sections = untranslatable_sections,
+                             .namespace_resolver = parser,
+                             .source = source_.WithLine(begin_xml_line)};
+}
+
+/**
+ * Reads the entire XML subtree and attempts to parse it as some Item,
+ * with typeMask denoting which items it can be. If allowRawValue is
+ * true, a RawString is returned if the XML couldn't be parsed as
+ * an Item. If allowRawValue is false, nullptr is returned in this
+ * case.
+ */
+std::unique_ptr<Item> ResourceParser::ParseXml(xml::XmlPullParser* parser, const uint32_t type_mask,
+                                               const bool allow_raw_value) {
+  auto sub_tree = CreateFlattenSubTree(parser);
+  if (!sub_tree.has_value()) {
+    return {};
+  }
+  return ParseXml(sub_tree.value(), type_mask, allow_raw_value, *table_, config_, *diag_);
+}
+
+std::unique_ptr<Item> ResourceParser::ParseXml(const FlattenedXmlSubTree& xmlsub_tree,
+                                               const uint32_t type_mask, const bool allow_raw_value,
+                                               ResourceTable& table,
+                                               const android::ConfigDescription& config,
+                                               IDiagnostics& diag) {
+  if (!xmlsub_tree.style_string.spans.empty()) {
     // This can only be a StyledString.
     std::unique_ptr<StyledString> styled_string =
-        util::make_unique<StyledString>(table_->string_pool.MakeRef(
-            style_string, StringPool::Context(StringPool::Context::kNormalPriority, config_)));
-    styled_string->untranslatable_sections = std::move(untranslatable_sections);
+        util::make_unique<StyledString>(table.string_pool.MakeRef(
+            xmlsub_tree.style_string,
+            StringPool::Context(StringPool::Context::kNormalPriority, config)));
+    styled_string->untranslatable_sections = xmlsub_tree.untranslatable_sections;
     return std::move(styled_string);
   }
 
   auto on_create_reference = [&](const ResourceName& name) {
     // name.package can be empty here, as it will assume the package name of the
     // table.
-    std::unique_ptr<Id> id = util::make_unique<Id>();
-    id->SetSource(source_.WithLine(begin_xml_line));
-    table_->AddResource(NewResourceBuilder(name).SetValue(std::move(id)).Build(), diag_);
+    auto id = util::make_unique<Id>();
+    id->SetSource(xmlsub_tree.source);
+    return table.AddResource(NewResourceBuilder(name).SetValue(std::move(id)).Build(), &diag);
   };
 
   // Process the raw value.
-  std::unique_ptr<Item> processed_item =
-      ResourceUtils::TryParseItemForAttribute(raw_value, type_mask, on_create_reference);
+  std::unique_ptr<Item> processed_item = ResourceUtils::TryParseItemForAttribute(
+      xmlsub_tree.raw_value, type_mask, on_create_reference);
   if (processed_item) {
     // Fix up the reference.
-    if (Reference* ref = ValueCast<Reference>(processed_item.get())) {
-      ResolvePackage(parser, ref);
+    if (auto ref = ValueCast<Reference>(processed_item.get())) {
+      ref->allow_raw = allow_raw_value;
+      ResolvePackage(xmlsub_tree.namespace_resolver, ref);
     }
     return processed_item;
   }
@@ -777,17 +809,16 @@
   if (type_mask & android::ResTable_map::TYPE_STRING) {
     // Use the trimmed, escaped string.
     std::unique_ptr<String> string = util::make_unique<String>(
-        table_->string_pool.MakeRef(style_string.str, StringPool::Context(config_)));
-    string->untranslatable_sections = std::move(untranslatable_sections);
+        table.string_pool.MakeRef(xmlsub_tree.style_string.str, StringPool::Context(config)));
+    string->untranslatable_sections = xmlsub_tree.untranslatable_sections;
     return std::move(string);
   }
 
   if (allow_raw_value) {
     // We can't parse this so return a RawString if we are allowed.
-    return util::make_unique<RawString>(
-        table_->string_pool.MakeRef(util::TrimWhitespace(raw_value),
-                                    StringPool::Context(config_)));
-  } else if (util::TrimWhitespace(raw_value).empty()) {
+    return util::make_unique<RawString>(table.string_pool.MakeRef(
+        util::TrimWhitespace(xmlsub_tree.raw_value), StringPool::Context(config)));
+  } else if (util::TrimWhitespace(xmlsub_tree.raw_value).empty()) {
     // If the text is empty, and the value is not allowed to be a string, encode it as a @null.
     return ResourceUtils::MakeNull();
   }
@@ -850,6 +881,35 @@
   return true;
 }
 
+bool ResourceParser::ParseMacro(xml::XmlPullParser* parser, ParsedResource* out_resource) {
+  auto sub_tree = CreateFlattenSubTree(parser);
+  if (!sub_tree) {
+    return false;
+  }
+
+  if (out_resource->config != ConfigDescription::DefaultConfig()) {
+    diag_->Error(DiagMessage(out_resource->source)
+                 << "<macro> tags cannot be declared in configurations other than the default "
+                    "configuration'");
+    return false;
+  }
+
+  auto macro = std::make_unique<Macro>();
+  macro->raw_value = std::move(sub_tree->raw_value);
+  macro->style_string = std::move(sub_tree->style_string);
+  macro->untranslatable_sections = std::move(sub_tree->untranslatable_sections);
+
+  for (const auto& decl : parser->package_decls()) {
+    macro->alias_namespaces.emplace_back(
+        Macro::Namespace{.alias = decl.prefix,
+                         .package_name = decl.package.package,
+                         .is_private = decl.package.private_namespace});
+  }
+
+  out_resource->value = std::move(macro);
+  return true;
+}
+
 bool ResourceParser::ParsePublic(xml::XmlPullParser* parser, ParsedResource* out_resource) {
   if (options_.visibility) {
     diag_->Error(DiagMessage(out_resource->source)
diff --git a/tools/aapt2/ResourceParser.h b/tools/aapt2/ResourceParser.h
index af0db8c..5c92def 100644
--- a/tools/aapt2/ResourceParser.h
+++ b/tools/aapt2/ResourceParser.h
@@ -57,6 +57,14 @@
   Maybe<Visibility::Level> visibility;
 };
 
+struct FlattenedXmlSubTree {
+  std::string raw_value;
+  StyleString style_string;
+  std::vector<UntranslatableSection> untranslatable_sections;
+  xml::IPackageDeclStack* namespace_resolver;
+  Source source;
+};
+
 /*
  * Parses an XML file for resources and adds them to a ResourceTable.
  */
@@ -67,9 +75,16 @@
                  const ResourceParserOptions& options = {});
   bool Parse(xml::XmlPullParser* parser);
 
+  static std::unique_ptr<Item> ParseXml(const FlattenedXmlSubTree& xmlsub_tree, uint32_t type_mask,
+                                        bool allow_raw_value, ResourceTable& table,
+                                        const android::ConfigDescription& config,
+                                        IDiagnostics& diag);
+
  private:
   DISALLOW_COPY_AND_ASSIGN(ResourceParser);
 
+  std::optional<FlattenedXmlSubTree> CreateFlattenSubTree(xml::XmlPullParser* parser);
+
   // Parses the XML subtree as a StyleString (flattened XML representation for strings with
   // formatting). If parsing fails, false is returned and the out parameters are left in an
   // unspecified state. Otherwise,
@@ -96,7 +111,7 @@
 
   bool ParseItem(xml::XmlPullParser* parser, ParsedResource* out_resource, uint32_t format);
   bool ParseString(xml::XmlPullParser* parser, ParsedResource* out_resource);
-
+  bool ParseMacro(xml::XmlPullParser* parser, ParsedResource* out_resource);
   bool ParsePublic(xml::XmlPullParser* parser, ParsedResource* out_resource);
   bool ParsePublicGroup(xml::XmlPullParser* parser, ParsedResource* out_resource);
   bool ParseStagingPublicGroup(xml::XmlPullParser* parser, ParsedResource* out_resource);
@@ -108,8 +123,7 @@
   bool ParseAttrImpl(xml::XmlPullParser* parser, ParsedResource* out_resource, bool weak);
   Maybe<Attribute::Symbol> ParseEnumOrFlagItem(xml::XmlPullParser* parser,
                                                const android::StringPiece& tag);
-  bool ParseStyle(const ResourceType type, xml::XmlPullParser* parser,
-                  ParsedResource* out_resource);
+  bool ParseStyle(ResourceType type, xml::XmlPullParser* parser, ParsedResource* out_resource);
   bool ParseStyleItem(xml::XmlPullParser* parser, Style* style);
   bool ParseDeclareStyleable(xml::XmlPullParser* parser, ParsedResource* out_resource);
   bool ParseArray(xml::XmlPullParser* parser, ParsedResource* out_resource);
diff --git a/tools/aapt2/ResourceParser_test.cpp b/tools/aapt2/ResourceParser_test.cpp
index 4a509be..279ebcba 100644
--- a/tools/aapt2/ResourceParser_test.cpp
+++ b/tools/aapt2/ResourceParser_test.cpp
@@ -336,6 +336,90 @@
   EXPECT_THAT(attr->type_mask, Eq(ResTable_map::TYPE_ANY));
 }
 
+TEST_F(ResourceParserTest, ParseMacro) {
+  std::string input = R"(<macro name="foo">12345</macro>)";
+  ASSERT_TRUE(TestParse(input));
+
+  Macro* macro = test::GetValue<Macro>(&table_, "macro/foo");
+  ASSERT_THAT(macro, NotNull());
+  EXPECT_THAT(macro->raw_value, Eq("12345"));
+  EXPECT_THAT(macro->style_string.str, Eq("12345"));
+  EXPECT_THAT(macro->style_string.spans, IsEmpty());
+  EXPECT_THAT(macro->untranslatable_sections, IsEmpty());
+  EXPECT_THAT(macro->alias_namespaces, IsEmpty());
+}
+
+TEST_F(ResourceParserTest, ParseMacroUntranslatableSection) {
+  std::string input = R"(<macro name="foo" xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
+This being <b><xliff:g>human</xliff:g></b> is a guest house.</macro>)";
+  ASSERT_TRUE(TestParse(input));
+
+  Macro* macro = test::GetValue<Macro>(&table_, "macro/foo");
+  ASSERT_THAT(macro, NotNull());
+  EXPECT_THAT(macro->raw_value, Eq("\nThis being human is a guest house."));
+  EXPECT_THAT(macro->style_string.str, Eq(" This being human is a guest house."));
+  EXPECT_THAT(macro->style_string.spans.size(), Eq(1));
+  EXPECT_THAT(macro->style_string.spans[0].name, Eq("b"));
+  EXPECT_THAT(macro->style_string.spans[0].first_char, Eq(12));
+  EXPECT_THAT(macro->style_string.spans[0].last_char, Eq(16));
+  ASSERT_THAT(macro->untranslatable_sections.size(), Eq(1));
+  EXPECT_THAT(macro->untranslatable_sections[0].start, Eq(12));
+  EXPECT_THAT(macro->untranslatable_sections[0].end, Eq(17));
+  EXPECT_THAT(macro->alias_namespaces, IsEmpty());
+}
+
+TEST_F(ResourceParserTest, ParseMacroNamespaces) {
+  std::string input = R"(<macro name="foo" xmlns:app="http://schemas.android.com/apk/res/android">
+@app:string/foo</macro>)";
+  ASSERT_TRUE(TestParse(input));
+
+  Macro* macro = test::GetValue<Macro>(&table_, "macro/foo");
+  ASSERT_THAT(macro, NotNull());
+  EXPECT_THAT(macro->raw_value, Eq("\n@app:string/foo"));
+  EXPECT_THAT(macro->style_string.str, Eq("@app:string/foo"));
+  EXPECT_THAT(macro->style_string.spans, IsEmpty());
+  EXPECT_THAT(macro->untranslatable_sections, IsEmpty());
+  EXPECT_THAT(macro->alias_namespaces.size(), Eq(1));
+  EXPECT_THAT(macro->alias_namespaces[0].alias, Eq("app"));
+  EXPECT_THAT(macro->alias_namespaces[0].package_name, Eq("android"));
+  EXPECT_THAT(macro->alias_namespaces[0].is_private, Eq(false));
+}
+
+TEST_F(ResourceParserTest, ParseMacroReference) {
+  std::string input = R"(<string name="res_string">@macro/foo</string>)";
+  ASSERT_TRUE(TestParse(input));
+
+  Reference* macro = test::GetValue<Reference>(&table_, "string/res_string");
+  ASSERT_THAT(macro, NotNull());
+  EXPECT_THAT(macro->type_flags, Eq(ResTable_map::TYPE_STRING));
+  EXPECT_THAT(macro->allow_raw, Eq(false));
+
+  input = R"(<style name="foo">
+               <item name="bar">@macro/foo</item>
+             </style>)";
+
+  ASSERT_TRUE(TestParse(input));
+  Style* style = test::GetValue<Style>(&table_, "style/foo");
+  ASSERT_THAT(style, NotNull());
+  EXPECT_THAT(style->entries.size(), Eq(1));
+
+  macro = ValueCast<Reference>(style->entries[0].value.get());
+  ASSERT_THAT(macro, NotNull());
+  EXPECT_THAT(macro->type_flags, Eq(0U));
+  EXPECT_THAT(macro->allow_raw, Eq(true));
+}
+
+TEST_F(ResourceParserTest, ParseMacroNoNameFail) {
+  std::string input = R"(<macro>12345</macro>)";
+  ASSERT_FALSE(TestParse(input));
+}
+
+TEST_F(ResourceParserTest, ParseMacroNonDefaultConfigurationFail) {
+  const ConfigDescription watch_config = test::ParseConfigOrDie("watch");
+  std::string input = R"(<macro name="foo">12345</macro>)";
+  ASSERT_FALSE(TestParse(input, watch_config));
+}
+
 // Old AAPT allowed attributes to be defined under different configurations, but ultimately
 // stored them with the default configuration. Check that we have the same behavior.
 TEST_F(ResourceParserTest, ParseAttrAndDeclareStyleableUnderConfigButRecordAsNoConfig) {
diff --git a/tools/aapt2/ResourceUtils.cpp b/tools/aapt2/ResourceUtils.cpp
index 5b43df6..e0e80ac 100644
--- a/tools/aapt2/ResourceUtils.cpp
+++ b/tools/aapt2/ResourceUtils.cpp
@@ -628,7 +628,7 @@
 
 std::unique_ptr<Item> TryParseItemForAttribute(
     const StringPiece& value, uint32_t type_mask,
-    const std::function<void(const ResourceName&)>& on_create_reference) {
+    const std::function<bool(const ResourceName&)>& on_create_reference) {
   using android::ResTable_map;
 
   auto null_or_empty = TryParseNullOrEmpty(value);
@@ -639,8 +639,11 @@
   bool create = false;
   auto reference = TryParseReference(value, &create);
   if (reference) {
+    reference->type_flags = type_mask;
     if (create && on_create_reference) {
-      on_create_reference(reference->name.value());
+      if (!on_create_reference(reference->name.value())) {
+        return {};
+      }
     }
     return std::move(reference);
   }
@@ -689,7 +692,7 @@
  */
 std::unique_ptr<Item> TryParseItemForAttribute(
     const StringPiece& str, const Attribute* attr,
-    const std::function<void(const ResourceName&)>& on_create_reference) {
+    const std::function<bool(const ResourceName&)>& on_create_reference) {
   using android::ResTable_map;
 
   const uint32_t type_mask = attr->type_mask;
diff --git a/tools/aapt2/ResourceUtils.h b/tools/aapt2/ResourceUtils.h
index f77766e..be493db 100644
--- a/tools/aapt2/ResourceUtils.h
+++ b/tools/aapt2/ResourceUtils.h
@@ -204,11 +204,11 @@
  */
 std::unique_ptr<Item> TryParseItemForAttribute(
     const android::StringPiece& value, const Attribute* attr,
-    const std::function<void(const ResourceName&)>& on_create_reference = {});
+    const std::function<bool(const ResourceName&)>& on_create_reference = {});
 
 std::unique_ptr<Item> TryParseItemForAttribute(
     const android::StringPiece& value, uint32_t type_mask,
-    const std::function<void(const ResourceName&)>& on_create_reference = {});
+    const std::function<bool(const ResourceName&)>& on_create_reference = {});
 
 uint32_t AndroidTypeToAttributeTypeMask(uint16_t type);
 
diff --git a/tools/aapt2/ResourceValues.cpp b/tools/aapt2/ResourceValues.cpp
index 574bd2e..2a90f26 100644
--- a/tools/aapt2/ResourceValues.cpp
+++ b/tools/aapt2/ResourceValues.cpp
@@ -111,12 +111,15 @@
   if (!other) {
     return false;
   }
-  return reference_type == other->reference_type &&
-         private_reference == other->private_reference && id == other->id &&
-         name == other->name;
+  return reference_type == other->reference_type && private_reference == other->private_reference &&
+         id == other->id && name == other->name && type_flags == other->type_flags;
 }
 
 bool Reference::Flatten(android::Res_value* out_value) const {
+  if (name && name.value().type == ResourceType::kMacro) {
+    return false;
+  }
+
   const ResourceId resid = id.value_or_default(ResourceId(0));
   const bool dynamic = resid.is_valid() && is_dynamic;
 
@@ -551,7 +554,7 @@
   return this_type_mask == that_type_mask;
 }
 
-std::string Attribute::MaskString() const {
+std::string Attribute::MaskString(uint32_t type_mask) {
   if (type_mask == android::ResTable_map::TYPE_ANY) {
     return "any";
   }
@@ -650,6 +653,10 @@
   return out.str();
 }
 
+std::string Attribute::MaskString() const {
+  return MaskString(type_mask);
+}
+
 void Attribute::Print(std::ostream* out) const {
   *out << "(attr) " << MaskString();
 
@@ -1017,6 +1024,21 @@
        << " [" << util::Joiner(entries, ", ") << "]";
 }
 
+bool Macro::Equals(const Value* value) const {
+  const Macro* other = ValueCast<Macro>(value);
+  if (!other) {
+    return false;
+  }
+  return other->raw_value == raw_value && other->style_string.spans == style_string.spans &&
+         other->style_string.str == style_string.str &&
+         other->untranslatable_sections == untranslatable_sections &&
+         other->alias_namespaces == alias_namespaces;
+}
+
+void Macro::Print(std::ostream* out) const {
+  *out << "(macro) ";
+}
+
 bool operator<(const Reference& a, const Reference& b) {
   int cmp = a.name.value_or_default({}).compare(b.name.value_or_default({}));
   if (cmp != 0) return cmp < 0;
@@ -1149,4 +1171,9 @@
   return CopyValueFields(std::move(new_value), value);
 }
 
+std::unique_ptr<Macro> CloningValueTransformer::TransformDerived(const Macro* value) {
+  auto new_value = std::make_unique<Macro>(*value);
+  return CopyValueFields(std::move(new_value), value);
+}
+
 }  // namespace aapt
diff --git a/tools/aapt2/ResourceValues.h b/tools/aapt2/ResourceValues.h
index 025864d..d11b013 100644
--- a/tools/aapt2/ResourceValues.h
+++ b/tools/aapt2/ResourceValues.h
@@ -164,6 +164,8 @@
   Reference::Type reference_type;
   bool private_reference = false;
   bool is_dynamic = false;
+  std::optional<uint32_t> type_flags;
+  bool allow_raw;
 
   Reference();
   explicit Reference(const ResourceNameRef& n, Type type = Type::kResource);
@@ -311,6 +313,8 @@
   bool IsCompatibleWith(const Attribute& attr) const;
 
   std::string MaskString() const;
+  static std::string MaskString(uint32_t type_mask);
+
   void Print(std::ostream* out) const override;
   bool Matches(const Item& item, DiagMessage* out_msg = nullptr) const;
 };
@@ -362,6 +366,28 @@
   void MergeWith(Styleable* styleable);
 };
 
+struct Macro : public TransformableValue<Macro, BaseValue<Macro>> {
+  std::string raw_value;
+  StyleString style_string;
+  std::vector<UntranslatableSection> untranslatable_sections;
+
+  struct Namespace {
+    std::string alias;
+    std::string package_name;
+    bool is_private;
+
+    bool operator==(const Namespace& right) const {
+      return alias == right.alias && package_name == right.package_name &&
+             is_private == right.is_private;
+    }
+  };
+
+  std::vector<Namespace> alias_namespaces;
+
+  bool Equals(const Value* value) const override;
+  void Print(std::ostream* out) const override;
+};
+
 template <typename T>
 typename std::enable_if<std::is_base_of<Value, T>::value, std::ostream&>::type operator<<(
     std::ostream& out, const std::unique_ptr<T>& value) {
@@ -388,6 +414,7 @@
   std::unique_ptr<Array> TransformDerived(const Array* value) override;
   std::unique_ptr<Plural> TransformDerived(const Plural* value) override;
   std::unique_ptr<Styleable> TransformDerived(const Styleable* value) override;
+  std::unique_ptr<Macro> TransformDerived(const Macro* value) override;
 };
 
 }  // namespace aapt
diff --git a/tools/aapt2/Resources.proto b/tools/aapt2/Resources.proto
index 4247ec5..b45c040 100644
--- a/tools/aapt2/Resources.proto
+++ b/tools/aapt2/Resources.proto
@@ -273,6 +273,7 @@
     Styleable styleable = 3;
     Array array = 4;
     Plural plural = 5;
+    MacroBody macro = 6;
   }
 }
 
@@ -304,6 +305,13 @@
 
   // Whether this reference is dynamic.
   Boolean is_dynamic = 5;
+
+  // The type flags used when compiling the reference. Used for substituting the contents of macros.
+  uint32 type_flags = 6;
+
+  // Whether raw string values would have been accepted in place of this reference definition. Used
+  // for substituting the contents of macros.
+  bool allow_raw = 7;
 }
 
 // A value that represents an ID. This is just a placeholder, as ID values are used to occupy a
@@ -591,3 +599,32 @@
   // The optional interpreted/compiled version of the `value` string.
   Item compiled_item = 6;
 }
+
+message MacroBody {
+  string raw_string = 1;
+  StyleString style_string = 2;
+  repeated UntranslatableSection untranslatable_sections = 3;
+  repeated NamespaceAlias namespace_stack = 4;
+  SourcePosition source = 5;
+}
+
+message NamespaceAlias {
+  string prefix = 1;
+  string package_name = 2;
+  bool is_private = 3;
+}
+
+message StyleString {
+  message Span {
+    string name = 1;
+    uint32 start_index = 2;
+    uint32 end_index = 3;
+  }
+  string str = 1;
+  repeated Span spans = 2;
+}
+
+message UntranslatableSection {
+  uint64 start_index = 1;
+  uint64 end_index = 2;
+}
\ No newline at end of file
diff --git a/tools/aapt2/StringPool.h b/tools/aapt2/StringPool.h
index 1006ca9..3457e0b 100644
--- a/tools/aapt2/StringPool.h
+++ b/tools/aapt2/StringPool.h
@@ -36,6 +36,10 @@
   std::string name;
   uint32_t first_char;
   uint32_t last_char;
+
+  bool operator==(const Span& right) const {
+    return name == right.name && first_char == right.first_char && last_char == right.last_char;
+  }
 };
 
 struct StyleString {
diff --git a/tools/aapt2/ValueTransformer.cpp b/tools/aapt2/ValueTransformer.cpp
index 6eb2e30..2d7996b 100644
--- a/tools/aapt2/ValueTransformer.cpp
+++ b/tools/aapt2/ValueTransformer.cpp
@@ -46,5 +46,6 @@
 VALUE_CREATE_VALUE_DECL(Array);
 VALUE_CREATE_VALUE_DECL(Plural);
 VALUE_CREATE_VALUE_DECL(Styleable);
+VALUE_CREATE_VALUE_DECL(Macro);
 
 }  // namespace aapt
\ No newline at end of file
diff --git a/tools/aapt2/ValueTransformer.h b/tools/aapt2/ValueTransformer.h
index 6925111..6fc4a19 100644
--- a/tools/aapt2/ValueTransformer.h
+++ b/tools/aapt2/ValueTransformer.h
@@ -37,6 +37,7 @@
 struct Array;
 struct Plural;
 struct Styleable;
+struct Macro;
 
 #define AAPT_TRANSFORM_VALUE(T)                                    \
   virtual std::unique_ptr<T> TransformDerived(const T* value) = 0; \
@@ -97,6 +98,7 @@
   AAPT_TRANSFORM_VALUE(Array);
   AAPT_TRANSFORM_VALUE(Plural);
   AAPT_TRANSFORM_VALUE(Styleable);
+  AAPT_TRANSFORM_VALUE(Macro);
 
  protected:
   StringPool* const pool_;
diff --git a/tools/aapt2/ValueVisitor.h b/tools/aapt2/ValueVisitor.h
index 4e74ec3..d0c9d89 100644
--- a/tools/aapt2/ValueVisitor.h
+++ b/tools/aapt2/ValueVisitor.h
@@ -43,6 +43,9 @@
   virtual void Visit(Array* value) { VisitAny(value); }
   virtual void Visit(Plural* value) { VisitAny(value); }
   virtual void Visit(Styleable* value) { VisitAny(value); }
+  virtual void Visit(Macro* value) {
+    VisitAny(value);
+  }
 };
 
 // Const version of ValueVisitor.
@@ -92,6 +95,9 @@
   virtual void Visit(const Styleable* value) {
     VisitAny(value);
   }
+  virtual void Visit(const Macro* value) {
+    VisitAny(value);
+  }
 };
 
 // NOLINT, do not add parentheses around T.
diff --git a/tools/aapt2/cmd/Link.cpp b/tools/aapt2/cmd/Link.cpp
index 2c57fb2..e4d0f3b 100644
--- a/tools/aapt2/cmd/Link.cpp
+++ b/tools/aapt2/cmd/Link.cpp
@@ -462,7 +462,7 @@
   // that existing projects have out-of-date references which pass compilation.
   xml::StripAndroidStudioAttributes(doc->root.get());
 
-  XmlReferenceLinker xml_linker;
+  XmlReferenceLinker xml_linker(table);
   if (!options_.do_not_fail_on_missing_resources && !xml_linker.Consume(context_, doc)) {
     return {};
   }
@@ -2112,7 +2112,7 @@
         std::unique_ptr<xml::XmlResource> split_manifest =
             GenerateSplitManifest(app_info_, *split_constraints_iter);
 
-        XmlReferenceLinker linker;
+        XmlReferenceLinker linker(&final_table_);
         if (!linker.Consume(context_, split_manifest.get())) {
           context_->GetDiagnostics()->Error(DiagMessage()
                                             << "failed to create Split AndroidManifest.xml");
@@ -2143,7 +2143,7 @@
       // So we give it a package name so it can see local resources.
       manifest_xml->file.name.package = context_->GetCompilationPackage();
 
-      XmlReferenceLinker manifest_linker;
+      XmlReferenceLinker manifest_linker(&final_table_);
       if (options_.merge_only || manifest_linker.Consume(context_, manifest_xml.get())) {
         if (options_.generate_proguard_rules_path &&
             !proguard::CollectProguardRulesForManifest(manifest_xml.get(), &proguard_keep_set)) {
diff --git a/tools/aapt2/cmd/Link_test.cpp b/tools/aapt2/cmd/Link_test.cpp
index d1e6d39..3118eb8 100644
--- a/tools/aapt2/cmd/Link_test.cpp
+++ b/tools/aapt2/cmd/Link_test.cpp
@@ -24,6 +24,7 @@
 
 using testing::Eq;
 using testing::HasSubstr;
+using testing::IsNull;
 using testing::Ne;
 using testing::NotNull;
 
@@ -532,4 +533,109 @@
   EXPECT_THAT(*result, Eq(0x01fd0072));
 }
 
+TEST_F(LinkTest, MacroSubstitution) {
+  StdErrDiagnostics diag;
+  const std::string values =
+      R"(<resources xmlns:an="http://schemas.android.com/apk/res/android">
+           <macro name="is_enabled">true</macro>
+           <macro name="deep_is_enabled">@macro/is_enabled</macro>
+           <macro name="attr_ref">?is_enabled_attr</macro>
+           <macro name="raw_string">Hello World!</macro>
+           <macro name="android_ref">@an:color/primary_text_dark</macro>
+
+           <attr name="is_enabled_attr" />
+           <public type="attr" name="is_enabled_attr" id="0x7f010000"/>
+
+           <string name="is_enabled_str">@macro/is_enabled</string>
+           <bool name="is_enabled_bool">@macro/deep_is_enabled</bool>
+
+           <array name="my_array">
+             <item>@macro/is_enabled</item>
+           </array>
+
+           <style name="MyStyle">
+              <item name="android:background">@macro/attr_ref</item>
+              <item name="android:fontFamily">@macro/raw_string</item>
+           </style>
+         </resources>)";
+
+  const std::string xml_values =
+      R"(<SomeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                     android:background="@macro/android_ref"
+                     android:fontFamily="@macro/raw_string">
+         </SomeLayout>)";
+
+  // Build a library with a public attribute
+  const std::string lib_res = GetTestPath("test-res");
+  ASSERT_TRUE(CompileFile(GetTestPath("res/values/values.xml"), values, lib_res, &diag));
+  ASSERT_TRUE(CompileFile(GetTestPath("res/layout/layout.xml"), xml_values, lib_res, &diag));
+
+  const std::string lib_apk = GetTestPath("test.apk");
+  // clang-format off
+  auto lib_link_args = LinkCommandBuilder(this)
+      .SetManifestFile(ManifestBuilder(this).SetPackageName("com.test").Build())
+      .AddCompiledResDir(lib_res, &diag)
+      .AddFlag("--no-auto-version")
+      .Build(lib_apk);
+  // clang-format on
+  ASSERT_TRUE(Link(lib_link_args, &diag));
+
+  auto apk = LoadedApk::LoadApkFromPath(lib_apk, &diag);
+  ASSERT_THAT(apk, NotNull());
+
+  // Test that the type flags determines the value type
+  auto actual_bool =
+      test::GetValue<BinaryPrimitive>(apk->GetResourceTable(), "com.test:bool/is_enabled_bool");
+  ASSERT_THAT(actual_bool, NotNull());
+  EXPECT_EQ(android::Res_value::TYPE_INT_BOOLEAN, actual_bool->value.dataType);
+  EXPECT_EQ(0xffffffffu, actual_bool->value.data);
+
+  auto actual_str =
+      test::GetValue<String>(apk->GetResourceTable(), "com.test:string/is_enabled_str");
+  ASSERT_THAT(actual_str, NotNull());
+  EXPECT_EQ(*actual_str->value, "true");
+
+  // Test nested data structures
+  auto actual_array = test::GetValue<Array>(apk->GetResourceTable(), "com.test:array/my_array");
+  ASSERT_THAT(actual_array, NotNull());
+  EXPECT_THAT(actual_array->elements.size(), Eq(1));
+
+  auto array_el_ref = ValueCast<BinaryPrimitive>(actual_array->elements[0].get());
+  ASSERT_THAT(array_el_ref, NotNull());
+  EXPECT_THAT(array_el_ref->value.dataType, Eq(android::Res_value::TYPE_INT_BOOLEAN));
+  EXPECT_THAT(array_el_ref->value.data, Eq(0xffffffffu));
+
+  auto actual_style = test::GetValue<Style>(apk->GetResourceTable(), "com.test:style/MyStyle");
+  ASSERT_THAT(actual_style, NotNull());
+  EXPECT_THAT(actual_style->entries.size(), Eq(2));
+
+  {
+    auto style_el = ValueCast<Reference>(actual_style->entries[0].value.get());
+    ASSERT_THAT(style_el, NotNull());
+    EXPECT_THAT(style_el->reference_type, Eq(Reference::Type::kAttribute));
+    EXPECT_THAT(style_el->id, Eq(0x7f010000));
+  }
+
+  {
+    auto style_el = ValueCast<String>(actual_style->entries[1].value.get());
+    ASSERT_THAT(style_el, NotNull());
+    EXPECT_THAT(*style_el->value, Eq("Hello World!"));
+  }
+
+  // Test substitution in compiled xml files
+  auto xml = apk->LoadXml("res/layout/layout.xml", &diag);
+  ASSERT_THAT(xml, NotNull());
+
+  auto& xml_attrs = xml->root->attributes;
+  ASSERT_THAT(xml_attrs.size(), Eq(2));
+
+  auto attr_value = ValueCast<Reference>(xml_attrs[0].compiled_value.get());
+  ASSERT_THAT(attr_value, NotNull());
+  EXPECT_THAT(attr_value->reference_type, Eq(Reference::Type::kResource));
+  EXPECT_THAT(attr_value->id, Eq(0x01060001));
+
+  EXPECT_THAT(xml_attrs[1].compiled_value.get(), IsNull());
+  EXPECT_THAT(xml_attrs[1].value, Eq("Hello World!"));
+}
+
 }  // namespace aapt
diff --git a/tools/aapt2/format/binary/TableFlattener.cpp b/tools/aapt2/format/binary/TableFlattener.cpp
index 17d11a6..74ecf47 100644
--- a/tools/aapt2/format/binary/TableFlattener.cpp
+++ b/tools/aapt2/format/binary/TableFlattener.cpp
@@ -567,13 +567,10 @@
   }
 
   bool FlattenTypes(BigBuffer* buffer) {
-    // Sort the types by their IDs. They will be inserted into the StringPool in
-    // this order.
-
     size_t expected_type_id = 1;
     for (const ResourceTableTypeView& type : package_.types) {
-      if (type.type == ResourceType::kStyleable) {
-        // Styleables aren't real Resource Types, they are represented in the R.java file.
+      if (type.type == ResourceType::kStyleable || type.type == ResourceType::kMacro) {
+        // Styleables and macros are not real resource types.
         continue;
       }
 
diff --git a/tools/aapt2/format/binary/XmlFlattener_test.cpp b/tools/aapt2/format/binary/XmlFlattener_test.cpp
index c24488b..d97e888 100644
--- a/tools/aapt2/format/binary/XmlFlattener_test.cpp
+++ b/tools/aapt2/format/binary/XmlFlattener_test.cpp
@@ -222,7 +222,7 @@
             android:id="@id/foo"
             app:foo="@id/foo" />)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   // The tree needs a custom DynamicRefTable since it is not using a standard app ID (0x7f).
diff --git a/tools/aapt2/format/proto/ProtoDeserialize.cpp b/tools/aapt2/format/proto/ProtoDeserialize.cpp
index 498d5a2..ec331df 100644
--- a/tools/aapt2/format/proto/ProtoDeserialize.cpp
+++ b/tools/aapt2/format/proto/ProtoDeserialize.cpp
@@ -656,6 +656,38 @@
     }
     out_ref->name = name_ref.ToResourceName();
   }
+  if (pb_ref.type_flags() != 0) {
+    out_ref->type_flags = pb_ref.type_flags();
+  }
+  out_ref->allow_raw = pb_ref.allow_raw();
+  return true;
+}
+
+static bool DeserializeMacroFromPb(const pb::MacroBody& pb_ref, Macro* out_ref,
+                                   std::string* out_error) {
+  out_ref->raw_value = pb_ref.raw_string();
+
+  if (pb_ref.has_style_string()) {
+    out_ref->style_string.str = pb_ref.style_string().str();
+    for (const auto& span : pb_ref.style_string().spans()) {
+      out_ref->style_string.spans.emplace_back(Span{
+          .name = span.name(), .first_char = span.start_index(), .last_char = span.end_index()});
+    }
+  }
+
+  for (const auto& untranslatable_section : pb_ref.untranslatable_sections()) {
+    out_ref->untranslatable_sections.emplace_back(
+        UntranslatableSection{.start = static_cast<size_t>(untranslatable_section.start_index()),
+                              .end = static_cast<size_t>(untranslatable_section.end_index())});
+  }
+
+  for (const auto& namespace_decls : pb_ref.namespace_stack()) {
+    out_ref->alias_namespaces.emplace_back(
+        Macro::Namespace{.alias = namespace_decls.prefix(),
+                         .package_name = namespace_decls.package_name(),
+                         .is_private = namespace_decls.is_private()});
+  }
+
   return true;
 }
 
@@ -801,6 +833,15 @@
         value = std::move(plural);
       } break;
 
+      case pb::CompoundValue::kMacro: {
+        const pb::MacroBody& pb_macro = pb_compound_value.macro();
+        auto macro = std::make_unique<Macro>();
+        if (!DeserializeMacroFromPb(pb_macro, macro.get(), out_error)) {
+          return {};
+        }
+        value = std::move(macro);
+      } break;
+
       default:
         LOG(FATAL) << "unknown compound value: " << (int)pb_compound_value.value_case();
         break;
diff --git a/tools/aapt2/format/proto/ProtoSerialize.cpp b/tools/aapt2/format/proto/ProtoSerialize.cpp
index f13f82d..d2f0336 100644
--- a/tools/aapt2/format/proto/ProtoSerialize.cpp
+++ b/tools/aapt2/format/proto/ProtoSerialize.cpp
@@ -440,6 +440,36 @@
   if (ref.is_dynamic) {
     pb_ref->mutable_is_dynamic()->set_value(ref.is_dynamic);
   }
+  if (ref.type_flags) {
+    pb_ref->set_type_flags(*ref.type_flags);
+  }
+  pb_ref->set_allow_raw(ref.allow_raw);
+}
+
+static void SerializeMacroToPb(const Macro& ref, pb::MacroBody* pb_macro) {
+  pb_macro->set_raw_string(ref.raw_value);
+
+  auto pb_style_str = pb_macro->mutable_style_string();
+  pb_style_str->set_str(ref.style_string.str);
+  for (const auto& span : ref.style_string.spans) {
+    auto pb_span = pb_style_str->add_spans();
+    pb_span->set_name(span.name);
+    pb_span->set_start_index(span.first_char);
+    pb_span->set_end_index(span.last_char);
+  }
+
+  for (const auto& untranslatable_section : ref.untranslatable_sections) {
+    auto pb_section = pb_macro->add_untranslatable_sections();
+    pb_section->set_start_index(untranslatable_section.start);
+    pb_section->set_end_index(untranslatable_section.end);
+  }
+
+  for (const auto& namespace_decls : ref.alias_namespaces) {
+    auto pb_namespace = pb_macro->add_namespace_stack();
+    pb_namespace->set_prefix(namespace_decls.alias);
+    pb_namespace->set_package_name(namespace_decls.package_name);
+    pb_namespace->set_is_private(namespace_decls.is_private);
+  }
 }
 
 template <typename T>
@@ -643,6 +673,11 @@
     }
   }
 
+  void Visit(const Macro* macro) override {
+    pb::MacroBody* pb_macro = out_value_->mutable_compound_value()->mutable_macro();
+    SerializeMacroToPb(*macro, pb_macro);
+  }
+
   void VisitAny(const Value* unknown) override {
     LOG(FATAL) << "unimplemented value: " << *unknown;
   }
diff --git a/tools/aapt2/format/proto/ProtoSerialize_test.cpp b/tools/aapt2/format/proto/ProtoSerialize_test.cpp
index 591ba149..e563eda 100644
--- a/tools/aapt2/format/proto/ProtoSerialize_test.cpp
+++ b/tools/aapt2/format/proto/ProtoSerialize_test.cpp
@@ -894,4 +894,38 @@
   EXPECT_THAT(*(s->value), Eq("foo"));
 }
 
+TEST(ProtoSerializeTest, SerializeMacro) {
+  auto original = std::make_unique<Macro>();
+  original->raw_value = "\nThis being human is a guest house.";
+  original->style_string.str = " This being human is a guest house.";
+  original->style_string.spans.emplace_back(Span{.name = "b", .first_char = 12, .last_char = 16});
+  original->untranslatable_sections.emplace_back(UntranslatableSection{.start = 12, .end = 17});
+  original->alias_namespaces.emplace_back(
+      Macro::Namespace{.alias = "prefix", .package_name = "package.name", .is_private = true});
+
+  CloningValueTransformer cloner(nullptr);
+  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();
+  std::unique_ptr<ResourceTable> table = test::ResourceTableBuilder()
+                                             .Add(NewResourceBuilder("com.app.a:macro/foo")
+                                                      .SetValue(original->Transform(cloner))
+                                                      .Build())
+                                             .Build();
+
+  ResourceTable new_table;
+  pb::ResourceTable pb_table;
+  MockFileCollection files;
+  std::string error;
+  SerializeTableToPb(*table, &pb_table, context->GetDiagnostics());
+  ASSERT_TRUE(DeserializeTableFromPb(pb_table, &files, &new_table, &error));
+  EXPECT_THAT(error, IsEmpty());
+
+  Macro* deserialized = test::GetValue<Macro>(&new_table, "com.app.a:macro/foo");
+  ASSERT_THAT(deserialized, NotNull());
+  EXPECT_THAT(deserialized->raw_value, Eq(original->raw_value));
+  EXPECT_THAT(deserialized->style_string.str, Eq(original->style_string.str));
+  EXPECT_THAT(deserialized->style_string.spans, Eq(original->style_string.spans));
+  EXPECT_THAT(deserialized->untranslatable_sections, Eq(original->untranslatable_sections));
+  EXPECT_THAT(deserialized->alias_namespaces, Eq(original->alias_namespaces));
+}
+
 }  // namespace aapt
diff --git a/tools/aapt2/java/JavaClassGenerator.cpp b/tools/aapt2/java/JavaClassGenerator.cpp
index e1e2e01..de6524d 100644
--- a/tools/aapt2/java/JavaClassGenerator.cpp
+++ b/tools/aapt2/java/JavaClassGenerator.cpp
@@ -616,8 +616,9 @@
 
   for (const auto& package : table_->packages) {
     for (const auto& type : package->types) {
-      if (type->type == ResourceType::kAttrPrivate) {
-        // We generate these as part of the kAttr type, so skip them here.
+      if (type->type == ResourceType::kAttrPrivate || type->type == ResourceType::kMacro) {
+        // We generate kAttrPrivate as part of the kAttr type, so skip them here.
+        // Macros are not actual resources, so skip them as well.
         continue;
       }
 
diff --git a/tools/aapt2/java/JavaClassGenerator_test.cpp b/tools/aapt2/java/JavaClassGenerator_test.cpp
index d08b61e..40395ed 100644
--- a/tools/aapt2/java/JavaClassGenerator_test.cpp
+++ b/tools/aapt2/java/JavaClassGenerator_test.cpp
@@ -570,4 +570,25 @@
   EXPECT_THAT(output, HasSubstr("public static final int MyStyleable_dynamic_attr=1;"));
 }
 
+TEST(JavaClassGeneratorTest, SkipMacros) {
+  std::unique_ptr<ResourceTable> table =
+      test::ResourceTableBuilder()
+          .AddValue("android:macro/bar", ResourceId(0x01010000), test::AttributeBuilder().Build())
+          .Build();
+
+  std::unique_ptr<IAaptContext> context =
+      test::ContextBuilder()
+          .AddSymbolSource(util::make_unique<ResourceTableSymbolSource>(table.get()))
+          .SetNameManglerPolicy(NameManglerPolicy{"android"})
+          .Build();
+  JavaClassGenerator generator(context.get(), table.get(), {});
+
+  std::string output;
+  StringOutputStream out(&output);
+  EXPECT_TRUE(generator.Generate("android", &out));
+  out.Flush();
+
+  EXPECT_THAT(output, Not(HasSubstr("bar")));
+}
+
 }  // namespace aapt
diff --git a/tools/aapt2/java/ProguardRules_test.cpp b/tools/aapt2/java/ProguardRules_test.cpp
index b7dfec3..e104066 100644
--- a/tools/aapt2/java/ProguardRules_test.cpp
+++ b/tools/aapt2/java/ProguardRules_test.cpp
@@ -264,7 +264,7 @@
       </View>)");
   foo_layout->file.name = test::ParseNameOrDie("com.foo:layout/foo");
 
-  XmlReferenceLinker xml_linker;
+  XmlReferenceLinker xml_linker(nullptr);
   ASSERT_TRUE(xml_linker.Consume(context.get(), bar_layout.get()));
   ASSERT_TRUE(xml_linker.Consume(context.get(), foo_layout.get()));
 
diff --git a/tools/aapt2/link/Linkers.h b/tools/aapt2/link/Linkers.h
index c9b8d39..be6c930 100644
--- a/tools/aapt2/link/Linkers.h
+++ b/tools/aapt2/link/Linkers.h
@@ -133,12 +133,14 @@
 // Once an XmlResource is processed by this linker, it is ready to be flattened.
 class XmlReferenceLinker : public IXmlResourceConsumer {
  public:
-  XmlReferenceLinker() = default;
+  explicit XmlReferenceLinker(ResourceTable* table) : table_(table) {
+  }
 
   bool Consume(IAaptContext* context, xml::XmlResource* resource) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(XmlReferenceLinker);
+  ResourceTable* table_;
 };
 
 }  // namespace aapt
diff --git a/tools/aapt2/link/ReferenceLinker.cpp b/tools/aapt2/link/ReferenceLinker.cpp
index 8e49fab..4ac25bd 100644
--- a/tools/aapt2/link/ReferenceLinker.cpp
+++ b/tools/aapt2/link/ReferenceLinker.cpp
@@ -21,6 +21,7 @@
 #include "androidfw/ResourceTypes.h"
 
 #include "Diagnostics.h"
+#include "ResourceParser.h"
 #include "ResourceTable.h"
 #include "ResourceUtils.h"
 #include "ResourceValues.h"
@@ -37,128 +38,153 @@
 using ::android::base::StringPrintf;
 
 namespace aapt {
-
 namespace {
-
-// The ReferenceLinkerVisitor will follow all references and make sure they point
-// to resources that actually exist, either in the local resource table, or as external
-// symbols. Once the target resource has been found, the ID of the resource will be assigned
-// to the reference object.
-//
-// NOTE: All of the entries in the ResourceTable must be assigned IDs.
-class ReferenceLinkerVisitor : public DescendingValueVisitor {
- public:
-  using DescendingValueVisitor::Visit;
-
-  ReferenceLinkerVisitor(const CallSite& callsite, IAaptContext* context, SymbolTable* symbols,
-                         StringPool* string_pool, xml::IPackageDeclStack* decl)
-      : callsite_(callsite),
-        context_(context),
-        symbols_(symbols),
-        package_decls_(decl),
-        string_pool_(string_pool) {}
-
-  void Visit(Reference* ref) override {
-    if (!ReferenceLinker::LinkReference(callsite_, ref, context_, symbols_, package_decls_)) {
-      error_ = true;
-    }
+struct LoggingResourceName {
+  LoggingResourceName(const Reference& ref, const CallSite& callsite,
+                      const xml::IPackageDeclStack* decls)
+      : ref_(ref), callsite_(callsite), decls_(decls) {
   }
 
-  // We visit the Style specially because during this phase, values of attributes are
-  // all RawString values. Now that we are expected to resolve all symbols, we can
-  // lookup the attributes to find out which types are allowed for the attributes' values.
-  void Visit(Style* style) override {
-    if (style->parent) {
-      Visit(&style->parent.value());
+  const Reference& ref_;
+  const CallSite& callsite_;
+  const xml::IPackageDeclStack* decls_;
+};
+
+inline ::std::ostream& operator<<(::std::ostream& out, const LoggingResourceName& name) {
+  if (!name.ref_.name) {
+    out << name.ref_.id.value();
+    return out;
+  }
+
+  out << name.ref_.name.value();
+
+  Reference fully_qualified = name.ref_;
+  xml::ResolvePackage(name.decls_, &fully_qualified);
+
+  ResourceName& full_name = fully_qualified.name.value();
+  if (full_name.package.empty()) {
+    full_name.package = name.callsite_.package;
+  }
+
+  if (full_name != name.ref_.name.value()) {
+    out << " (aka " << full_name << ")";
+  }
+  return out;
+}
+
+}  // namespace
+
+std::unique_ptr<Reference> ReferenceLinkerTransformer::TransformDerived(const Reference* value) {
+  auto linked_item =
+      ReferenceLinker::LinkReference(callsite_, *value, context_, symbols_, table_, package_decls_);
+  if (linked_item) {
+    auto linked_item_ptr = linked_item.release();
+    if (auto ref = ValueCast<Reference>(linked_item_ptr)) {
+      return std::unique_ptr<Reference>(ref);
     }
+    context_->GetDiagnostics()->Error(DiagMessage(value->GetSource())
+                                      << "value of '"
+                                      << LoggingResourceName(*value, callsite_, package_decls_)
+                                      << "' must be a resource reference");
+    delete linked_item_ptr;
+  }
 
-    for (Style::Entry& entry : style->entries) {
-      std::string err_str;
+  error_ = true;
+  return CloningValueTransformer::TransformDerived(value);
+}
 
-      // Transform the attribute reference so that it is using the fully qualified package
-      // name. This will also mark the reference as being able to see private resources if
-      // there was a '*' in the reference or if the package came from the private namespace.
-      Reference transformed_reference = entry.key;
-      ResolvePackage(package_decls_, &transformed_reference);
+std::unique_ptr<Style> ReferenceLinkerTransformer::TransformDerived(const Style* style) {
+  // We visit the Style specially because during this phase, values of attributes are either
+  // RawString or Reference values. Now that we are expected to resolve all symbols, we can lookup
+  // the attributes to find out which types are allowed for the attributes' values.
+  auto new_style = CloningValueTransformer::TransformDerived(style);
+  if (new_style->parent) {
+    new_style->parent = *TransformDerived(&style->parent.value());
+  }
 
-      // Find the attribute in the symbol table and check if it is visible from this callsite.
-      const SymbolTable::Symbol* symbol = ReferenceLinker::ResolveAttributeCheckVisibility(
-          transformed_reference, callsite_, context_, symbols_, &err_str);
-      if (symbol) {
-        // Assign our style key the correct ID. The ID may not exist.
-        entry.key.id = symbol->id;
+  for (Style::Entry& entry : new_style->entries) {
+    std::string err_str;
 
-        // Try to convert the value to a more specific, typed value based on the attribute it is
-        // set to.
-        entry.value = ParseValueWithAttribute(std::move(entry.value), symbol->attribute.get());
+    // Transform the attribute reference so that it is using the fully qualified package
+    // name. This will also mark the reference as being able to see private resources if
+    // there was a '*' in the reference or if the package came from the private namespace.
+    Reference transformed_reference = entry.key;
+    ResolvePackage(package_decls_, &transformed_reference);
 
-        // Link/resolve the final value (mostly if it's a reference).
-        entry.value->Accept(this);
+    // Find the attribute in the symbol table and check if it is visible from this callsite.
+    const SymbolTable::Symbol* symbol = ReferenceLinker::ResolveAttributeCheckVisibility(
+        transformed_reference, callsite_, context_, symbols_, &err_str);
+    if (symbol) {
+      // Assign our style key the correct ID. The ID may not exist.
+      entry.key.id = symbol->id;
 
-        // Now verify that the type of this item is compatible with the
-        // attribute it is defined for. We pass `nullptr` as the DiagMessage so that this
-        // check is fast and we avoid creating a DiagMessage when the match is successful.
-        if (!symbol->attribute->Matches(*entry.value, nullptr)) {
-          // The actual type of this item is incompatible with the attribute.
-          DiagMessage msg(entry.key.GetSource());
+      // Link/resolve the final value if it's a reference.
+      entry.value = entry.value->Transform(*this);
 
-          // Call the matches method again, this time with a DiagMessage so we fill in the actual
-          // error message.
-          symbol->attribute->Matches(*entry.value, &msg);
-          context_->GetDiagnostics()->Error(msg);
-          error_ = true;
-        }
+      // Try to convert the value to a more specific, typed value based on the attribute it is
+      // set to.
+      entry.value = ParseValueWithAttribute(std::move(entry.value), symbol->attribute.get());
 
-      } else {
+      // Now verify that the type of this item is compatible with the
+      // attribute it is defined for. We pass `nullptr` as the DiagMessage so that this
+      // check is fast and we avoid creating a DiagMessage when the match is successful.
+      if (!symbol->attribute->Matches(*entry.value, nullptr)) {
+        // The actual type of this item is incompatible with the attribute.
         DiagMessage msg(entry.key.GetSource());
-        msg << "style attribute '";
-        ReferenceLinker::WriteResourceName(entry.key, callsite_, package_decls_, &msg);
-        msg << "' " << err_str;
+
+        // Call the matches method again, this time with a DiagMessage so we fill in the actual
+        // error message.
+        symbol->attribute->Matches(*entry.value, &msg);
         context_->GetDiagnostics()->Error(msg);
         error_ = true;
       }
+    } else {
+      context_->GetDiagnostics()->Error(DiagMessage(entry.key.GetSource())
+                                        << "style attribute '"
+                                        << LoggingResourceName(entry.key, callsite_, package_decls_)
+                                        << "' " << err_str);
+
+      error_ = true;
     }
   }
+  return new_style;
+}
 
-  bool HasError() {
-    return error_;
+std::unique_ptr<Item> ReferenceLinkerTransformer::TransformItem(const Reference* value) {
+  auto linked_value =
+      ReferenceLinker::LinkReference(callsite_, *value, context_, symbols_, table_, package_decls_);
+  if (linked_value) {
+    return linked_value;
   }
+  error_ = true;
+  return CloningValueTransformer::TransformDerived(value);
+}
 
- private:
-  DISALLOW_COPY_AND_ASSIGN(ReferenceLinkerVisitor);
+// Transform a RawString value into a more specific, appropriate value, based on the
+// Attribute. If a non RawString value is passed in, this is an identity transform.
+std::unique_ptr<Item> ReferenceLinkerTransformer::ParseValueWithAttribute(
+    std::unique_ptr<Item> value, const Attribute* attr) {
+  if (RawString* raw_string = ValueCast<RawString>(value.get())) {
+    std::unique_ptr<Item> transformed =
+        ResourceUtils::TryParseItemForAttribute(*raw_string->value, attr);
 
-  // Transform a RawString value into a more specific, appropriate value, based on the
-  // Attribute. If a non RawString value is passed in, this is an identity transform.
-  std::unique_ptr<Item> ParseValueWithAttribute(std::unique_ptr<Item> value,
-                                                const Attribute* attr) {
-    if (RawString* raw_string = ValueCast<RawString>(value.get())) {
-      std::unique_ptr<Item> transformed =
-          ResourceUtils::TryParseItemForAttribute(*raw_string->value, attr);
-
-      // If we could not parse as any specific type, try a basic STRING.
-      if (!transformed && (attr->type_mask & android::ResTable_map::TYPE_STRING)) {
-        StringBuilder string_builder;
-        string_builder.AppendText(*raw_string->value);
-        if (string_builder) {
-          transformed =
-              util::make_unique<String>(string_pool_->MakeRef(string_builder.to_string()));
-        }
-      }
-
-      if (transformed) {
-        return transformed;
+    // If we could not parse as any specific type, try a basic STRING.
+    if (!transformed && (attr->type_mask & android::ResTable_map::TYPE_STRING)) {
+      StringBuilder string_builder;
+      string_builder.AppendText(*raw_string->value);
+      if (string_builder) {
+        transformed = util::make_unique<String>(pool_->MakeRef(string_builder.to_string()));
       }
     }
-    return value;
-  }
 
-  const CallSite& callsite_;
-  IAaptContext* context_;
-  SymbolTable* symbols_;
-  xml::IPackageDeclStack* package_decls_;
-  StringPool* string_pool_;
-  bool error_ = false;
-};
+    if (transformed) {
+      return transformed;
+    }
+  }
+  return value;
+}
+
+namespace {
 
 class EmptyDeclStack : public xml::IPackageDeclStack {
  public:
@@ -175,6 +201,27 @@
   DISALLOW_COPY_AND_ASSIGN(EmptyDeclStack);
 };
 
+struct MacroDeclStack : public xml::IPackageDeclStack {
+  explicit MacroDeclStack(std::vector<Macro::Namespace> namespaces)
+      : alias_namespaces_(std::move(namespaces)) {
+  }
+
+  Maybe<xml::ExtractedPackage> TransformPackageAlias(const StringPiece& alias) const override {
+    if (alias.empty()) {
+      return xml::ExtractedPackage{{}, true /*private*/};
+    }
+    for (auto it = alias_namespaces_.rbegin(); it != alias_namespaces_.rend(); ++it) {
+      if (alias == StringPiece(it->alias)) {
+        return xml::ExtractedPackage{it->package_name, it->is_private};
+      }
+    }
+    return {};
+  }
+
+ private:
+  std::vector<Macro::Namespace> alias_namespaces_;
+};
+
 // The symbol is visible if it is public, or if the reference to it is requesting private access
 // or if the callsite comes from the same package.
 bool IsSymbolVisible(const SymbolTable::Symbol& symbol, const Reference& ref,
@@ -220,8 +267,6 @@
       // If the callsite package is the same as the current compilation package,
       // check the feature split dependencies as well. Feature split resources
       // can be referenced without a namespace, just like the base package.
-      // TODO: modify the package name of included splits instead of having the
-      // symbol table look up the resource in in every package. b/136105066
       if (callsite.package == context->GetCompilationPackage()) {
         const auto& split_name_dependencies = context->GetSplitNameDependencies();
         for (const std::string& split_name : split_name_dependencies) {
@@ -295,29 +340,6 @@
   return xml::AaptAttribute(*symbol->attribute, symbol->id);
 }
 
-void ReferenceLinker::WriteResourceName(const Reference& ref, const CallSite& callsite,
-                                        const xml::IPackageDeclStack* decls, DiagMessage* out_msg) {
-  CHECK(out_msg != nullptr);
-  if (!ref.name) {
-    *out_msg << ref.id.value();
-    return;
-  }
-
-  *out_msg << ref.name.value();
-
-  Reference fully_qualified = ref;
-  xml::ResolvePackage(decls, &fully_qualified);
-
-  ResourceName& full_name = fully_qualified.name.value();
-  if (full_name.package.empty()) {
-    full_name.package = callsite.package;
-  }
-
-  if (full_name != ref.name.value()) {
-    *out_msg << " (aka " << full_name << ")";
-  }
-}
-
 void ReferenceLinker::WriteAttributeName(const Reference& ref, const CallSite& callsite,
                                          const xml::IPackageDeclStack* decls,
                                          DiagMessage* out_msg) {
@@ -348,18 +370,71 @@
   }
 }
 
-bool ReferenceLinker::LinkReference(const CallSite& callsite, Reference* reference,
-                                    IAaptContext* context, SymbolTable* symbols,
-                                    const xml::IPackageDeclStack* decls) {
-  CHECK(reference != nullptr);
-  if (!reference->name && !reference->id) {
+std::unique_ptr<Item> ReferenceLinker::LinkReference(const CallSite& callsite,
+                                                     const Reference& reference,
+                                                     IAaptContext* context, SymbolTable* symbols,
+                                                     ResourceTable* table,
+                                                     const xml::IPackageDeclStack* decls) {
+  if (!reference.name && !reference.id) {
     // This is @null.
-    return true;
+    return std::make_unique<Reference>(reference);
   }
 
-  Reference transformed_reference = *reference;
+  Reference transformed_reference = reference;
   xml::ResolvePackage(decls, &transformed_reference);
 
+  if (transformed_reference.name.value().type == ResourceType::kMacro) {
+    if (transformed_reference.name.value().package.empty()) {
+      transformed_reference.name.value().package = callsite.package;
+    }
+
+    auto result = table->FindResource(transformed_reference.name.value());
+    if (!result || result.value().entry->values.empty()) {
+      context->GetDiagnostics()->Error(
+          DiagMessage(reference.GetSource())
+          << "failed to find definition for "
+          << LoggingResourceName(transformed_reference, callsite, decls));
+      return {};
+    }
+
+    auto& macro_values = result.value().entry->values;
+    CHECK(macro_values.size() == 1) << "Macros can only be defined in the default configuration.";
+
+    auto macro = ValueCast<Macro>(macro_values[0]->value.get());
+    CHECK(macro != nullptr) << "Value of macro resource is not a Macro (actual "
+                            << *macro_values[0]->value << ")";
+
+    // Re-create the state used to parse the macro tag to compile the macro contents as if it was
+    // defined inline
+    uint32_t type_flags = 0;
+    if (reference.type_flags.has_value()) {
+      type_flags = reference.type_flags.value();
+    }
+
+    MacroDeclStack namespace_stack(macro->alias_namespaces);
+    FlattenedXmlSubTree sub_tree{.raw_value = macro->raw_value,
+                                 .style_string = macro->style_string,
+                                 .untranslatable_sections = macro->untranslatable_sections,
+                                 .namespace_resolver = &namespace_stack,
+                                 .source = macro->GetSource()};
+
+    auto new_value = ResourceParser::ParseXml(sub_tree, type_flags, reference.allow_raw, *table,
+                                              macro_values[0]->config, *context->GetDiagnostics());
+    if (new_value == nullptr) {
+      context->GetDiagnostics()->Error(
+          DiagMessage(reference.GetSource())
+          << "failed to substitute macro "
+          << LoggingResourceName(transformed_reference, callsite, decls)
+          << ": failed to parse contents as one of type(s) " << Attribute::MaskString(type_flags));
+      return {};
+    }
+
+    if (auto ref = ValueCast<Reference>(new_value.get())) {
+      return LinkReference(callsite, *ref, context, symbols, table, decls);
+    }
+    return new_value;
+  }
+
   std::string err_str;
   const SymbolTable::Symbol* s =
       ResolveSymbolCheckVisibility(transformed_reference, callsite, context, symbols, &err_str);
@@ -367,17 +442,17 @@
     // The ID may not exist. This is fine because of the possibility of building
     // against libraries without assigned IDs.
     // Ex: Linking against own resources when building a static library.
-    reference->id = s->id;
-    reference->is_dynamic = s->is_dynamic;
-    return true;
+    auto new_ref = std::make_unique<Reference>(reference);
+    new_ref->id = s->id;
+    new_ref->is_dynamic = s->is_dynamic;
+    return std::move(new_ref);
   }
 
-  DiagMessage error_msg(reference->GetSource());
-  error_msg << "resource ";
-  WriteResourceName(*reference, callsite, decls, &error_msg);
-  error_msg << " " << err_str;
-  context->GetDiagnostics()->Error(error_msg);
-  return false;
+  context->GetDiagnostics()->Error(DiagMessage(reference.GetSource())
+                                   << "resource "
+                                   << LoggingResourceName(transformed_reference, callsite, decls)
+                                   << " " << err_str);
+  return {};
 }
 
 bool ReferenceLinker::Consume(IAaptContext* context, ResourceTable* table) {
@@ -412,14 +487,15 @@
 
         // The context of this resource is the package in which it is defined.
         const CallSite callsite{name.package};
-        ReferenceLinkerVisitor visitor(callsite, context, context->GetExternalSymbols(),
-                                       &table->string_pool, &decl_stack);
+        ReferenceLinkerTransformer reference_transformer(callsite, context,
+                                                         context->GetExternalSymbols(),
+                                                         &table->string_pool, table, &decl_stack);
 
         for (auto& config_value : entry->values) {
-          config_value->value->Accept(&visitor);
+          config_value->value = config_value->value->Transform(reference_transformer);
         }
 
-        if (visitor.HasError()) {
+        if (reference_transformer.HasError()) {
           error = true;
         }
       }
diff --git a/tools/aapt2/link/ReferenceLinker.h b/tools/aapt2/link/ReferenceLinker.h
index 1256709..770f1e5 100644
--- a/tools/aapt2/link/ReferenceLinker.h
+++ b/tools/aapt2/link/ReferenceLinker.h
@@ -28,6 +28,41 @@
 
 namespace aapt {
 
+// A ValueTransformer that returns fully linked versions of resource and macro references.
+class ReferenceLinkerTransformer : public CloningValueTransformer {
+ public:
+  ReferenceLinkerTransformer(const CallSite& callsite, IAaptContext* context, SymbolTable* symbols,
+                             StringPool* string_pool, ResourceTable* table,
+                             xml::IPackageDeclStack* decl)
+      : CloningValueTransformer(string_pool),
+        callsite_(callsite),
+        context_(context),
+        symbols_(symbols),
+        table_(table),
+        package_decls_(decl) {
+  }
+
+  std::unique_ptr<Reference> TransformDerived(const Reference* value) override;
+  std::unique_ptr<Item> TransformItem(const Reference* value) override;
+  std::unique_ptr<Style> TransformDerived(const Style* value) override;
+
+  bool HasError() {
+    return error_;
+  }
+
+ private:
+  // Transform a RawString value into a more specific, appropriate value, based on the
+  // Attribute. If a non RawString value is passed in, this is an identity transform.
+  std::unique_ptr<Item> ParseValueWithAttribute(std::unique_ptr<Item> value, const Attribute* attr);
+
+  const CallSite& callsite_;
+  IAaptContext* context_;
+  SymbolTable* symbols_;
+  ResourceTable* table_;
+  xml::IPackageDeclStack* package_decls_;
+  bool error_ = false;
+};
+
 // Resolves all references to resources in the ResourceTable and assigns them IDs.
 // The ResourceTable must already have IDs assigned to each resource.
 // Once the ResourceTable is processed by this linker, it is ready to be flattened.
@@ -70,19 +105,28 @@
 
   // Writes the resource name to the DiagMessage, using the
   // "orig_name (aka <transformed_name>)" syntax.
-  static void WriteResourceName(const Reference& orig, const CallSite& callsite,
-                                const xml::IPackageDeclStack* decls, DiagMessage* out_msg);
+  /*static void WriteResourceName(const Reference& orig, const CallSite& callsite,
+                                const xml::IPackageDeclStack* decls, DiagMessage* out_msg);*/
 
   // Same as WriteResourceName but omits the 'attr' part.
   static void WriteAttributeName(const Reference& ref, const CallSite& callsite,
                                  const xml::IPackageDeclStack* decls, DiagMessage* out_msg);
 
-  // Transforms the package name of the reference to the fully qualified package name using
-  // the xml::IPackageDeclStack, then mangles and looks up the symbol. If the symbol is visible
-  // to the reference at the callsite, the reference is updated with an ID.
-  // Returns false on failure, and an error message is logged to the IDiagnostics in the context.
-  static bool LinkReference(const CallSite& callsite, Reference* reference, IAaptContext* context,
-                            SymbolTable* symbols, const xml::IPackageDeclStack* decls);
+  // Returns a fully linked version a resource reference.
+  //
+  // If the reference points to a non-macro resource, the xml::IPackageDeclStack is used to
+  // determine the fully qualified name of the referenced resource. If the symbol is visible
+  // to the reference at the callsite, a copy of the reference with an updated updated ID is
+  // returned.
+  //
+  // If the reference points to a macro, the ResourceTable is used to find the macro definition and
+  // substitute its contents in place of the reference.
+  //
+  // Returns nullptr on failure, and an error message is logged to the IDiagnostics in the context.
+  static std::unique_ptr<Item> LinkReference(const CallSite& callsite, const Reference& reference,
+                                             IAaptContext* context, SymbolTable* symbols,
+                                             ResourceTable* table,
+                                             const xml::IPackageDeclStack* decls);
 
   // Links all references in the ResourceTable.
   bool Consume(IAaptContext* context, ResourceTable* table) override;
diff --git a/tools/aapt2/link/ReferenceLinker_test.cpp b/tools/aapt2/link/ReferenceLinker_test.cpp
index 228c5bd74..2d8f0d3 100644
--- a/tools/aapt2/link/ReferenceLinker_test.cpp
+++ b/tools/aapt2/link/ReferenceLinker_test.cpp
@@ -365,4 +365,22 @@
   EXPECT_THAT(s, IsNull());
 }
 
+TEST(ReferenceLinkerTest, MacroFailToFindDefinition) {
+  std::unique_ptr<ResourceTable> table =
+      test::ResourceTableBuilder()
+          .AddReference("com.app.test:string/foo", ResourceId(0x7f020000), "com.app.test:macro/bar")
+          .Build();
+
+  std::unique_ptr<IAaptContext> context =
+      test::ContextBuilder()
+          .SetCompilationPackage("com.app.test")
+          .SetPackageId(0x7f)
+          .SetNameManglerPolicy(NameManglerPolicy{"com.app.test"})
+          .AddSymbolSource(util::make_unique<ResourceTableSymbolSource>(table.get()))
+          .Build();
+
+  ReferenceLinker linker;
+  ASSERT_FALSE(linker.Consume(context.get(), table.get()));
+}
+
 }  // namespace aapt
diff --git a/tools/aapt2/link/XmlCompatVersioner_test.cpp b/tools/aapt2/link/XmlCompatVersioner_test.cpp
index a98ab0f..d638096 100644
--- a/tools/aapt2/link/XmlCompatVersioner_test.cpp
+++ b/tools/aapt2/link/XmlCompatVersioner_test.cpp
@@ -82,7 +82,7 @@
           app:foo="16dp"
           foo="bar"/>)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   XmlCompatVersioner::Rules rules;
@@ -121,7 +121,7 @@
           app:foo="16dp"
           foo="bar"/>)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   XmlCompatVersioner::Rules rules;
@@ -181,7 +181,7 @@
       <View xmlns:android="http://schemas.android.com/apk/res/android"
           android:paddingHorizontal="24dp" />)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   XmlCompatVersioner::Rules rules;
@@ -256,7 +256,7 @@
           android:paddingLeft="16dp"
           android:paddingRight="16dp"/>)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   Item* padding_horizontal_value =
diff --git a/tools/aapt2/link/XmlReferenceLinker.cpp b/tools/aapt2/link/XmlReferenceLinker.cpp
index c3c16b9..aaa085e 100644
--- a/tools/aapt2/link/XmlReferenceLinker.cpp
+++ b/tools/aapt2/link/XmlReferenceLinker.cpp
@@ -33,49 +33,18 @@
 
 namespace {
 
-// Visits all references (including parents of styles, references in styles, arrays, etc) and
-// links their symbolic name to their Resource ID, performing mangling and package aliasing
-// as needed.
-class ReferenceVisitor : public DescendingValueVisitor {
- public:
-  using DescendingValueVisitor::Visit;
-
-  ReferenceVisitor(const CallSite& callsite, IAaptContext* context, SymbolTable* symbols,
-                   xml::IPackageDeclStack* decls)
-      : callsite_(callsite), context_(context), symbols_(symbols), decls_(decls), error_(false) {}
-
-  void Visit(Reference* ref) override {
-    if (!ReferenceLinker::LinkReference(callsite_, ref, context_, symbols_, decls_)) {
-      error_ = true;
-    }
-  }
-
-  bool HasError() const {
-    return error_;
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(ReferenceVisitor);
-
-  const CallSite& callsite_;
-  IAaptContext* context_;
-  SymbolTable* symbols_;
-  xml::IPackageDeclStack* decls_;
-  bool error_;
-};
-
 // Visits each xml Element and compiles the attributes within.
 class XmlVisitor : public xml::PackageAwareVisitor {
  public:
   using xml::PackageAwareVisitor::Visit;
 
-  XmlVisitor(const Source& source, const CallSite& callsite, IAaptContext* context,
-             SymbolTable* symbols)
+  XmlVisitor(const Source& source, StringPool* pool, const CallSite& callsite,
+             IAaptContext* context, ResourceTable* table, SymbolTable* symbols)
       : source_(source),
         callsite_(callsite),
         context_(context),
         symbols_(symbols),
-        reference_visitor_(callsite, context, symbols, this) {
+        reference_transformer_(callsite, context, symbols, pool, table, this) {
   }
 
   void Visit(xml::Element* el) override {
@@ -127,7 +96,7 @@
       if (attr.compiled_value) {
         // With a compiledValue, we must resolve the reference and assign it an ID.
         attr.compiled_value->SetSource(source);
-        attr.compiled_value->Accept(&reference_visitor_);
+        attr.compiled_value = attr.compiled_value->Transform(reference_transformer_);
       } else if ((attribute->type_mask & android::ResTable_map::TYPE_STRING) == 0) {
         // We won't be able to encode this as a string.
         DiagMessage msg(source);
@@ -143,7 +112,7 @@
   }
 
   bool HasError() {
-    return error_ || reference_visitor_.HasError();
+    return error_ || reference_transformer_.HasError();
   }
 
  private:
@@ -154,7 +123,7 @@
   IAaptContext* context_;
   SymbolTable* symbols_;
 
-  ReferenceVisitor reference_visitor_;
+  ReferenceLinkerTransformer reference_transformer_;
   bool error_ = false;
 };
 
@@ -173,7 +142,8 @@
     callsite.package = context->GetCompilationPackage();
   }
 
-  XmlVisitor visitor(resource->file.source, callsite, context, context->GetExternalSymbols());
+  XmlVisitor visitor(resource->file.source, &resource->string_pool, callsite, context, table_,
+                     context->GetExternalSymbols());
   if (resource->root) {
     resource->root->Accept(&visitor);
     return !visitor.HasError();
diff --git a/tools/aapt2/link/XmlReferenceLinker_test.cpp b/tools/aapt2/link/XmlReferenceLinker_test.cpp
index 0ce2e50..ddf5b9a 100644
--- a/tools/aapt2/link/XmlReferenceLinker_test.cpp
+++ b/tools/aapt2/link/XmlReferenceLinker_test.cpp
@@ -91,7 +91,7 @@
             nonAaptAttrRef="@id/id"
             class="hello" />)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   xml::Element* view_el = doc->root.get();
@@ -144,7 +144,7 @@
       <View xmlns:android="http://schemas.android.com/apk/res/android"
           android:colorAccent="@android:color/hidden" />)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_FALSE(linker.Consume(context_.get(), doc.get()));
 }
 
@@ -153,7 +153,7 @@
     <View xmlns:android="http://schemas.android.com/apk/res/android"
           android:colorAccent="@*android:color/hidden" />)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 }
 
@@ -162,7 +162,7 @@
       <View xmlns:support="http://schemas.android.com/apk/res/com.android.support"
           support:colorAccent="#ff0000" />)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   xml::Element* view_el = doc->root.get();
@@ -181,7 +181,7 @@
       <View xmlns:app="http://schemas.android.com/apk/res-auto"
           app:colorAccent="@app:color/red" />)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   xml::Element* view_el = doc->root.get();
@@ -203,7 +203,7 @@
         <View xmlns:app="http://schemas.android.com/apk/res/com.app.test" app:attr="@app:id/id"/>
       </View>)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   xml::Element* view_el = doc->root.get();
@@ -239,7 +239,7 @@
       <View xmlns:android="http://schemas.android.com/apk/res/com.app.test"
           android:attr="@id/id"/>)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   xml::Element* view_el = doc->root.get();
@@ -261,7 +261,7 @@
   std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
     <gradient />)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   xml::Element* gradient_el = doc->root.get();
@@ -283,7 +283,7 @@
   <gradient xmlns:android="http://schemas.android.com/apk/res/android"
       android:angle="90"/>)");
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   xml::Element* gradient_el = doc->root.get();
@@ -305,7 +305,7 @@
   <gradient xmlns:android="http://schemas.android.com/apk/res/android" />)");
   context_->SetMinSdkVersion(30);
 
-  XmlReferenceLinker linker;
+  XmlReferenceLinker linker(nullptr);
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
   xml::Element* gradient_el = doc->root.get();
diff --git a/tools/aapt2/xml/XmlPullParser.cpp b/tools/aapt2/xml/XmlPullParser.cpp
index a023494..182203d 100644
--- a/tools/aapt2/xml/XmlPullParser.cpp
+++ b/tools/aapt2/xml/XmlPullParser.cpp
@@ -177,6 +177,10 @@
   return event_queue_.front().data2;
 }
 
+const std::vector<XmlPullParser::PackageDecl>& XmlPullParser::package_decls() const {
+  return package_aliases_;
+}
+
 XmlPullParser::const_iterator XmlPullParser::begin_attributes() const {
   return event_queue_.front().attributes.begin();
 }
diff --git a/tools/aapt2/xml/XmlPullParser.h b/tools/aapt2/xml/XmlPullParser.h
index 6ebaa28..5da2d4b 100644
--- a/tools/aapt2/xml/XmlPullParser.h
+++ b/tools/aapt2/xml/XmlPullParser.h
@@ -123,6 +123,13 @@
    */
   Maybe<ExtractedPackage> TransformPackageAlias(const android::StringPiece& alias) const override;
 
+  struct PackageDecl {
+    std::string prefix;
+    ExtractedPackage package;
+  };
+
+  const std::vector<PackageDecl>& package_decls() const;
+
   //
   // Remaining methods are for retrieving information about attributes
   // associated with a StartElement.
@@ -180,11 +187,6 @@
   const std::string empty_;
   size_t depth_;
   std::stack<std::string> namespace_uris_;
-
-  struct PackageDecl {
-    std::string prefix;
-    ExtractedPackage package;
-  };
   std::vector<PackageDecl> package_aliases_;
 };