diff --git a/java/com/google/gerrit/httpd/raw/IndexHtmlUtil.java b/java/com/google/gerrit/httpd/raw/IndexHtmlUtil.java
index 905c013..d7e9e44 100644
--- a/java/com/google/gerrit/httpd/raw/IndexHtmlUtil.java
+++ b/java/com/google/gerrit/httpd/raw/IndexHtmlUtil.java
@@ -49,10 +49,13 @@
       String canonicalURL,
       String cdnPath,
       String faviconPath,
+      Map<String, String[]> urlParameterMap,
       Function<String, SanitizedContent> urlInScriptTagOrdainer)
       throws URISyntaxException, RestApiException {
     return ImmutableMap.<String, Object>builder()
-        .putAll(staticTemplateData(canonicalURL, cdnPath, faviconPath, urlInScriptTagOrdainer))
+        .putAll(
+            staticTemplateData(
+                canonicalURL, cdnPath, faviconPath, urlParameterMap, urlInScriptTagOrdainer))
         .putAll(dynamicTemplateData(gerritApi))
         .build();
   }
@@ -94,6 +97,7 @@
       String canonicalURL,
       String cdnPath,
       String faviconPath,
+      Map<String, String[]> urlParameterMap,
       Function<String, SanitizedContent> urlInScriptTagOrdainer)
       throws URISyntaxException {
     String canonicalPath = computeCanonicalPath(canonicalURL);
@@ -116,6 +120,9 @@
     if (faviconPath != null) {
       data.put("faviconPath", faviconPath);
     }
+    if (urlParameterMap.containsKey("p2")) {
+      data.put("polymer2", "true");
+    }
     return data.build();
   }
 
diff --git a/java/com/google/gerrit/httpd/raw/IndexServlet.java b/java/com/google/gerrit/httpd/raw/IndexServlet.java
index 8299bfc..978f3eb 100644
--- a/java/com/google/gerrit/httpd/raw/IndexServlet.java
+++ b/java/com/google/gerrit/httpd/raw/IndexServlet.java
@@ -17,6 +17,7 @@
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static javax.servlet.http.HttpServletResponse.SC_OK;
 
+import com.google.common.collect.ImmutableMap;
 import com.google.common.io.Resources;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.api.GerritApi;
@@ -28,6 +29,7 @@
 import java.io.IOException;
 import java.io.OutputStream;
 import java.net.URISyntaxException;
+import java.util.Map;
 import java.util.function.Function;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
@@ -67,14 +69,16 @@
   protected void doGet(HttpServletRequest req, HttpServletResponse rsp) throws IOException {
     SoyTofu.Renderer renderer;
     try {
+      Map<String, String[]> parameterMap = req.getParameterMap();
       // TODO(hiesel): Remove URL ordainer as parameter once Soy is consistent
+      ImmutableMap<String, Object> templateData =
+          IndexHtmlUtil.templateData(
+              gerritApi, canonicalUrl, cdnPath, faviconPath, parameterMap, urlOrdainer);
       renderer =
           soyTofu
               .newRenderer("com.google.gerrit.httpd.raw.Index")
               .setContentKind(SanitizedContent.ContentKind.HTML)
-              .setData(
-                  IndexHtmlUtil.templateData(
-                      gerritApi, canonicalUrl, cdnPath, faviconPath, urlOrdainer));
+              .setData(templateData);
     } catch (URISyntaxException | RestApiException e) {
       throw new IOException(e);
     }
diff --git a/javatests/com/google/gerrit/httpd/raw/IndexHtmlUtilTest.java b/javatests/com/google/gerrit/httpd/raw/IndexHtmlUtilTest.java
index a4b6ab2..d695c48 100644
--- a/javatests/com/google/gerrit/httpd/raw/IndexHtmlUtilTest.java
+++ b/javatests/com/google/gerrit/httpd/raw/IndexHtmlUtilTest.java
@@ -17,21 +17,42 @@
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.gerrit.httpd.raw.IndexHtmlUtil.staticTemplateData;
 
+import com.google.common.collect.ImmutableMap;
 import com.google.template.soy.data.SanitizedContent;
 import com.google.template.soy.data.UnsafeSanitizedContentOrdainer;
+import java.util.HashMap;
 import org.junit.Test;
 
 public class IndexHtmlUtilTest {
   @Test
+  public void polymer2() throws Exception {
+    assertThat(
+            staticTemplateData(
+                "http://example.com/",
+                null,
+                null,
+                ImmutableMap.of("p2", new String[0]),
+                IndexHtmlUtilTest::ordain))
+        .containsExactly("canonicalPath", "", "polymer2", "true", "staticResourcePath", ordain(""));
+  }
+
+  @Test
   public void noPathAndNoCDN() throws Exception {
-    assertThat(staticTemplateData("http://example.com/", null, null, IndexHtmlUtilTest::ordain))
+    assertThat(
+            staticTemplateData(
+                "http://example.com/", null, null, new HashMap<>(), IndexHtmlUtilTest::ordain))
         .containsExactly("canonicalPath", "", "staticResourcePath", ordain(""));
   }
 
   @Test
   public void pathAndNoCDN() throws Exception {
     assertThat(
-            staticTemplateData("http://example.com/gerrit/", null, null, IndexHtmlUtilTest::ordain))
+            staticTemplateData(
+                "http://example.com/gerrit/",
+                null,
+                null,
+                new HashMap<>(),
+                IndexHtmlUtilTest::ordain))
         .containsExactly("canonicalPath", "/gerrit", "staticResourcePath", ordain("/gerrit"));
   }
 
@@ -42,6 +63,7 @@
                 "http://example.com/",
                 "http://my-cdn.com/foo/bar/",
                 null,
+                new HashMap<>(),
                 IndexHtmlUtilTest::ordain))
         .containsExactly(
             "canonicalPath", "", "staticResourcePath", ordain("http://my-cdn.com/foo/bar/"));
@@ -54,6 +76,7 @@
                 "http://example.com/gerrit",
                 "http://my-cdn.com/foo/bar/",
                 null,
+                new HashMap<>(),
                 IndexHtmlUtilTest::ordain))
         .containsExactly(
             "canonicalPath", "/gerrit", "staticResourcePath", ordain("http://my-cdn.com/foo/bar/"));
diff --git a/polygerrit-ui/app/elements/gr-app-p2.html b/polygerrit-ui/app/elements/gr-app-p2.html
new file mode 100644
index 0000000..2ce5ed8
--- /dev/null
+++ b/polygerrit-ui/app/elements/gr-app-p2.html
@@ -0,0 +1,40 @@
+<!--
+@license
+Copyright (C) 2019 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.
+-->
+<script>
+  window.Gerrit = window.Gerrit || {};
+</script>
+
+<link rel="import" href="/bower_components/polymer/polymer.html">
+<link rel="import" href="/bower_components/polymer-resin/polymer-resin.html">
+<link rel="import" href="/bower_components/polymer/lib/legacy/legacy-data-mixin.html">
+<link rel="import" href="/bower_components/shadycss/apply-shim.html">
+<link rel="import" href="../behaviors/safe-types-behavior/safe-types-behavior.html">
+<script>
+  security.polymer_resin.install({
+    allowedIdentifierPrefixes: [''],
+    reportHandler: security.polymer_resin.CONSOLE_LOGGING_REPORT_HANDLER,
+    safeTypesBridge: Gerrit.SafeTypes.safeTypesBridge,
+  });
+</script>
+
+<link rel="import" href="./gr-app-element.html">
+<dom-module id="gr-app-p2">
+  <template>
+    <gr-app-element id="app-element"></gr-app-element>
+  </template>
+  <script src="gr-app-p2.js" crossorigin="anonymous"></script>
+</dom-module>
diff --git a/polygerrit-ui/app/elements/gr-app-p2.js b/polygerrit-ui/app/elements/gr-app-p2.js
new file mode 100644
index 0000000..2163c02
--- /dev/null
+++ b/polygerrit-ui/app/elements/gr-app-p2.js
@@ -0,0 +1,23 @@
+/**
+ * @license
+ * Copyright (C) 2019 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.
+ */
+(function() {
+  'use strict';
+
+  Polymer({
+    is: 'gr-app-p2',
+  });
+})();
diff --git a/polygerrit-ui/app/elements/gr-app.html b/polygerrit-ui/app/elements/gr-app.html
index 1a31d4c..e2d2680 100644
--- a/polygerrit-ui/app/elements/gr-app.html
+++ b/polygerrit-ui/app/elements/gr-app.html
@@ -15,25 +15,22 @@
 limitations under the License.
 -->
 <script>
-  if (!window.POLYMER2) {
-    // This must be set prior to loading Polymer for the first time.
-    if (localStorage.getItem('USE_SHADOW_DOM') === 'true') {
-      window.Polymer = {
-        dom: 'shadow',
-        passiveTouchGestures: true,
-      };
-    } else if (!window.Polymer) {
-      window.Polymer = {
-        passiveTouchGestures: true,
-      };
-    }
+  // This must be set prior to loading Polymer for the first time.
+  if (localStorage.getItem('USE_SHADOW_DOM') === 'true') {
+    window.Polymer = {
+      dom: 'shadow',
+      passiveTouchGestures: true,
+    };
+  } else if (!window.Polymer) {
+    window.Polymer = {
+      passiveTouchGestures: true,
+    };
   }
   window.Gerrit = window.Gerrit || {};
 </script>
 
 <link rel="import" href="/bower_components/polymer/polymer.html">
 <link rel="import" href="/bower_components/polymer-resin/standalone/polymer-resin.html">
-<link rel="import" href="/bower_components/polymer/lib/legacy/legacy-data-mixin.html">
 <link rel="import" href="../behaviors/safe-types-behavior/safe-types-behavior.html">
 <script>
   security.polymer_resin.install({
diff --git a/polygerrit-ui/app/elements/gr-app.js b/polygerrit-ui/app/elements/gr-app.js
index 2298b2f..5c74659 100644
--- a/polygerrit-ui/app/elements/gr-app.js
+++ b/polygerrit-ui/app/elements/gr-app.js
@@ -21,9 +21,7 @@
   // requestAnimationFrame.)
   // @see https://github.com/Polymer/polymer/issues/3851
   // @see Issue 4699
-  if (!window.POLYMER2) {
-    Polymer.RenderStatus._makeReady();
-  }
+  Polymer.RenderStatus._makeReady();
 
   Polymer({
     is: 'gr-app',
diff --git a/resources/com/google/gerrit/httpd/raw/PolyGerritIndexHtml.soy b/resources/com/google/gerrit/httpd/raw/PolyGerritIndexHtml.soy
index bca05db..c907ae9 100644
--- a/resources/com/google/gerrit/httpd/raw/PolyGerritIndexHtml.soy
+++ b/resources/com/google/gerrit/httpd/raw/PolyGerritIndexHtml.soy
@@ -79,7 +79,13 @@
   <link rel="preload" href="{$staticResourcePath}/fonts/Roboto-Medium.woff" as="font" type="font/woff" crossorigin="anonymous">{\n}
   <link rel="stylesheet" href="{$staticResourcePath}/styles/fonts.css">{\n}
   <link rel="stylesheet" href="{$staticResourcePath}/styles/main.css">{\n}
-  <script src="{$staticResourcePath}/bower_components/webcomponentsjs/webcomponents-lite.js"></script>{\n}
+
+  {if $polymer2}
+    <script src="{$staticResourcePath}/bower_components/webcomponentsjs-p2/webcomponents-lite.js"></script>{\n}
+  {else}
+    <script src="{$staticResourcePath}/bower_components/webcomponentsjs/webcomponents-lite.js"></script>{\n}
+  {/if}
+
   // Content between webcomponents-lite and the load of the main app element
   // run before polymer-resin is installed so may have security consequences.
   // Contact your local security engineer if you have any questions, and
@@ -90,9 +96,18 @@
     <link rel="import" href="{$assetsPath}/{$assetsBundle}">{\n}
   {/if}
 
-  <link rel="preload" href="{$staticResourcePath}/elements/gr-app.js" as="script" crossorigin="anonymous">{\n}
-  <link rel="import" href="{$staticResourcePath}/elements/gr-app.html">{\n}
+  {if $polymer2}
+    <link rel="preload" href="{$staticResourcePath}/elements/gr-app-p2.js" as="script" crossorigin="anonymous">{\n}
+    <link rel="import" href="{$staticResourcePath}/elements/gr-app-p2.html">{\n}
+  {else}
+    <link rel="preload" href="{$staticResourcePath}/elements/gr-app.js" as="script" crossorigin="anonymous">{\n}
+    <link rel="import" href="{$staticResourcePath}/elements/gr-app.html">{\n}
+  {/if}
 
   <body unresolved>{\n}
-  <gr-app id="app"></gr-app>{\n}
+  {if $polymer2}
+    <gr-app-p2 id="app"></gr-app-p2>{\n}
+  {else}
+    <gr-app id="app"></gr-app>{\n}
+  {/if}
 {/template}