diff --git a/WORKSPACE b/WORKSPACE
index cc25af7..41d6ef8 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -49,49 +49,25 @@
 # otherwise refer to RBE docs.
 rbe_autoconfig(name = "rbe_default")
 
-# TODO(davido): Switch to upstream again, when this PR is merged:
-# https://github.com/bazelbuild/rules_closure/pull/478
 http_archive(
-    name = "io_bazel_rules_closure",
-    sha256 = "b9c2bc6ba377aa497eb7c31681d34404febf9d4e3c9c7d98ce0d78238a0af20f",
-    strip_prefix = "rules_closure-0.31",
+    name = "com_google_protobuf",
+    sha256 = "71030a04aedf9f612d2991c1c552317038c3c5a2b578ac4745267a45e7037c29",
+    strip_prefix = "protobuf-3.12.3",
     urls = [
-        "https://github.com/davido/rules_closure/archive/V0.31.tar.gz",
-        "https://gerrit-ci.gerritforge.com/lib/V0.31.tar.gz",
+        "https://github.com/protocolbuffers/protobuf/archive/v3.12.3.tar.gz",
     ],
 )
 
+load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
+
+protobuf_deps()
+
 http_archive(
     name = "build_bazel_rules_nodejs",
     sha256 = "84abf7ac4234a70924628baa9a73a5a5cbad944c4358cf9abdb4aab29c9a5b77",
     urls = ["https://github.com/bazelbuild/rules_nodejs/releases/download/1.7.0/rules_nodejs-1.7.0.tar.gz"],
 )
 
-# File is specific to Polymer and copied from the Closure Github -- should be
-# synced any time there are major changes to Polymer.
-# https://github.com/google/closure-compiler/blob/master/contrib/externs/polymer-1.0.js
-http_file(
-    name = "polymer_closure",
-    downloaded_file_path = "polymer_closure.js",
-    sha256 = "4d63a36dcca040475bd6deb815b9a600bd686e1413ac1ebd4b04516edd675020",
-    urls = ["https://raw.githubusercontent.com/google/closure-compiler/35d2b3340ff23a69441f10fa3bc820691c2942f2/contrib/externs/polymer-1.0.js"],
-)
-
-load("@io_bazel_rules_closure//closure:repositories.bzl", "rules_closure_dependencies", "rules_closure_toolchains")
-
-# Prevent redundant loading of dependencies.
-# TODO(davido): Omit re-fetching ancient args4j version when these PRs are merged:
-# https://github.com/bazelbuild/rules_closure/pull/262
-# https://github.com/google/closure-templates/pull/155
-rules_closure_dependencies(
-    omit_aopalliance = True,
-    omit_bazel_skylib = True,
-    omit_javax_inject = True,
-    omit_rules_cc = True,
-)
-
-rules_closure_toolchains()
-
 # Golang support for PolyGerrit local dev server.
 http_archive(
     name = "io_bazel_rules_go",
@@ -328,7 +304,7 @@
 )
 
 maven_jar(
-    name = "args4j-intern",
+    name = "args4j",
     artifact = "args4j:args4j:2.33",
     sha1 = "bd87a75374a6d6523de82fef51fc3cfe9baf9fc9",
 )
diff --git a/lib/BUILD b/lib/BUILD
index d3ef4b9..0110047 100644
--- a/lib/BUILD
+++ b/lib/BUILD
@@ -160,7 +160,7 @@
     name = "args4j",
     data = ["//lib:LICENSE-args4j"],
     visibility = ["//visibility:public"],
-    exports = ["@args4j-intern//jar"],
+    exports = ["@args4j//jar"],
 )
 
 java_library(
diff --git a/lib/polymer_externs/BUILD b/lib/polymer_externs/BUILD
deleted file mode 100644
index f07aa2f..0000000
--- a/lib/polymer_externs/BUILD
+++ /dev/null
@@ -1,24 +0,0 @@
-# Copyright (C) 2017 The Android Open Source Project
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-load("@io_bazel_rules_closure//closure:defs.bzl", "closure_js_library")
-
-package(default_visibility = ["//visibility:public"])
-
-closure_js_library(
-    name = "polymer_closure",
-    srcs = ["@polymer_closure//file"],
-    data = ["//lib:LICENSE-Apache2.0"],
-    no_closure_library = True,
-)
diff --git a/polygerrit-ui/app/externs/BUILD b/polygerrit-ui/app/externs/BUILD
deleted file mode 100644
index 26ead9a..0000000
--- a/polygerrit-ui/app/externs/BUILD
+++ /dev/null
@@ -1,25 +0,0 @@
-# Copyright (C) 2018 The Android Open Source Project
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-load("@io_bazel_rules_closure//closure:defs.bzl", "closure_js_library")
-
-package(
-    default_visibility = ["//visibility:public"],
-)
-
-closure_js_library(
-    name = "plugin",
-    srcs = ["plugin.js"],
-    no_closure_library = True,
-)
diff --git a/polygerrit-ui/app/externs/plugin.js b/polygerrit-ui/app/externs/plugin.js
deleted file mode 100644
index c88c724..0000000
--- a/polygerrit-ui/app/externs/plugin.js
+++ /dev/null
@@ -1,30 +0,0 @@
-/**
- * @license
- * Copyright (C) 2018 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/**
- * @fileoverview Closure compiler externs for the Gerrit UI plugins.
- * @externs
- */
-
-/* eslint-disable no-var */
-
-var Gerrit = {};
-
-/**
- * @param {!Function} callback
- */
-Gerrit.install = function(callback) {};