diff --git a/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.html b/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.html
index a3c44e2412..ad4e2b0f8f 100644
--- a/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.html
+++ b/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.html
@@ -15,6 +15,7 @@ limitations under the License.
 -->
 
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
+<link rel="import" href="../../../behaviors/base-url-behavior/base-url-behavior.html">
 <link rel="import" href="../../shared/gr-js-api-interface/gr-js-api-interface.html">
 
 <dom-module id="gr-plugin-host">
diff --git a/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.js b/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.js
index 3868534b7b..efad106464 100644
--- a/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.js
+++ b/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.js
@@ -24,6 +24,10 @@
       },
     },
 
+    behaviors: [
+      Gerrit.BaseUrlBehavior,
+    ],
+
     _configChanged(config) {
       const jsPlugins = config.js_resource_paths || [];
       const htmlPlugins = config.html_resource_paths || [];
@@ -33,21 +37,16 @@
     },
 
     _importHtmlPlugins(plugins) {
-      for (let url of plugins) {
-        if (!url.startsWith('http')) {
-          url = '/' + url;
-        }
+      for (const url of plugins) {
         this.importHref(
-            url, Gerrit._pluginInstalled, Gerrit._pluginInstalled, true);
+            this._urlFor(url), Gerrit._pluginInstalled, Gerrit._pluginInstalled,
+            true);
       }
     },
 
     _loadJsPlugins(plugins) {
-      for (let url of plugins) {
-        if (!url.startsWith('http')) {
-          url = '/' + url;
-        }
-        this._createScriptTag(url);
+      for (const url of plugins) {
+        this._createScriptTag(this._urlFor(url));
       }
     },
 
@@ -58,5 +57,12 @@
       el.onerror = Gerrit._pluginInstalled;
       return document.body.appendChild(el);
     },
+
+    _urlFor(pathOrUrl) {
+      if (pathOrUrl.startsWith('http')) {
+        return pathOrUrl;
+      }
+      return this.getBaseUrl() + '/' + pathOrUrl;
+    },
   });
 })();
diff --git a/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host_test.html b/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host_test.html
index b746a3364d..ead07819ed 100644
--- a/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host_test.html
+++ b/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host_test.html
@@ -54,7 +54,7 @@ limitations under the License.
       assert.isTrue(Gerrit._setPluginsCount.calledWith(3));
     });
 
-    test('imports html plugins from config', () => {
+    test('imports relative html plugins from config', () => {
       element.config = {
         html_resource_paths: ['foo/bar', 'baz'],
       };
@@ -64,13 +64,72 @@ limitations under the License.
           '/baz', Gerrit._pluginInstalled, Gerrit._pluginInstalled, true));
     });
 
-    test('imports js plugins from config', () => {
+    test('imports relative html plugins from config with a base url', () => {
+      sandbox.stub(element, 'getBaseUrl').returns('/the-base');
+      element.config = {
+        html_resource_paths: ['foo/bar', 'baz'],
+      };
+      assert.isTrue(element.importHref.calledWith(
+          '/the-base/foo/bar', Gerrit._pluginInstalled, Gerrit._pluginInstalled,
+          true));
+      assert.isTrue(element.importHref.calledWith(
+          '/the-base/baz', Gerrit._pluginInstalled, Gerrit._pluginInstalled,
+          true));
+    });
+
+    test('imports absolute html plugins from config', () => {
+      element.config = {
+        html_resource_paths: [
+          'http://example.com/foo/bar',
+          'https://example.com/baz',
+        ],
+      };
+      assert.isTrue(element.importHref.calledWith(
+          'http://example.com/foo/bar', Gerrit._pluginInstalled,
+          Gerrit._pluginInstalled, true));
+      assert.isTrue(element.importHref.calledWith(
+          'https://example.com/baz', Gerrit._pluginInstalled,
+          Gerrit._pluginInstalled, true));
+    });
+
+    test('adds js plugins from config to the body', () => {
+      element.config = {
+        js_resource_paths: ['foo/bar', 'baz'],
+      };
+      assert.isTrue(document.body.appendChild.calledTwice);
+    });
+
+    test('imports relative js plugins from config', () => {
       sandbox.stub(element, '_createScriptTag');
       element.config = {
-        js_resource_paths: ['foo/bar', 'http://baz'],
+        js_resource_paths: ['foo/bar', 'baz'],
       };
       assert.isTrue(element._createScriptTag.calledWith('/foo/bar'));
-      assert.isTrue(element._createScriptTag.calledWith('http://baz'));
+      assert.isTrue(element._createScriptTag.calledWith('/baz'));
+    });
+
+    test('imports relative html plugins from config with a base url', () => {
+      sandbox.stub(element, '_createScriptTag');
+      sandbox.stub(element, 'getBaseUrl').returns('/the-base');
+      element.config = {
+        js_resource_paths: ['foo/bar', 'baz'],
+      };
+      assert.isTrue(element._createScriptTag.calledWith('/the-base/foo/bar'));
+      assert.isTrue(element._createScriptTag.calledWith('/the-base/baz'));
+    });
+
+    test('imports absolute html plugins from config', () => {
+      sandbox.stub(element, '_createScriptTag');
+      element.config = {
+        js_resource_paths: [
+          'http://example.com/foo/bar',
+          'https://example.com/baz',
+        ],
+      };
+      assert.isTrue(element._createScriptTag.calledWith(
+          'http://example.com/foo/bar'));
+      assert.isTrue(element._createScriptTag.calledWith(
+          'https://example.com/baz'));
     });
   });
 </script>
diff --git a/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.html b/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.html
index 32b6f6729e..4095d3e7c0 100644
--- a/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.html
+++ b/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.html
@@ -16,6 +16,7 @@ limitations under the License.
 
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
 <link rel="import" href="../gr-rest-api-interface/gr-rest-api-interface.html">
+<link rel="import" href="../../../behaviors/base-url-behavior/base-url-behavior.html">
 <link rel="import" href="../../../styles/shared-styles.html">
 
 <dom-module id="gr-avatar">
diff --git a/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.js b/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.js
index 166204bf59..5fca577814 100644
--- a/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.js
+++ b/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.js
@@ -28,6 +28,10 @@
       },
     },
 
+    behaviors: [
+      Gerrit.BaseUrlBehavior,
+    ],
+
     created() {
       this.hidden = true;
     },
@@ -64,7 +68,8 @@
           return avatars[i].url;
         }
       }
-      return '/accounts/' + account._account_id + '/avatar?s=' + this.imageSize;
+      return this.getBaseUrl() + '/accounts/' +
+        account._account_id + '/avatar?s=' + this.imageSize;
     },
   });
 })();