diff --git a/src/lib/annotations/annotations.html b/src/lib/annotations/annotations.html
index bcd6879316..acfdcb06bc 100644
--- a/src/lib/annotations/annotations.html
+++ b/src/lib/annotations/annotations.html
@@ -66,7 +66,7 @@
   // null-array (shared empty array to avoid null-checks)
   Polymer.nar = [];
 
-  var inertEnabled = Polymer.Settings.enableInert;
+  var disableUpgradeEnabled = Polymer.Settings.disableUpgradeEnabled;
 
   Polymer.Annotations = {
 
@@ -370,11 +370,10 @@
           node.setAttribute(origName, '');
         }
         // Remove annotation
-        if (inertEnabled && origName === 'is-inert') {
-          node.setAttribute('is-inert', '');
-        } else {
-          node.removeAttribute(origName);
+        if (disableUpgradeEnabled && name === 'disable-upgrade') {
+          node.setAttribute(name, '');
         }
+        node.removeAttribute(origName);
         // Case hackery: attributes are lower-case, but bind targets
         // (properties) are case sensitive. Gambit is to map dash-case to
         // camel-case: `foo-bar` becomes `fooBar`.
diff --git a/src/lib/base.html b/src/lib/base.html
index 726e54cdd3..a6c53a3b14 100644
--- a/src/lib/base.html
+++ b/src/lib/base.html
@@ -64,14 +64,16 @@
     },
 
     createdCallback: function() {
-      if (Polymer.Settings.enableInert && this.hasAttribute('is-inert')) {
-        this.__data__ = {
-          isInert: true
-        };
-        this._propertySetter = inertPropertySetter;
-      } else {
-        this.__initialize();
+      if (Polymer.Settings.disableUpgradeEnabled) {
+        if (this.hasAttribute('disable-upgrade')) {
+          this._propertySetter = disableUpgradePropertySetter;
+          this.__data__ = {};
+          return;
+        } else {
+          this.__hasInitialized = true;
+        }
       }
+      this.__initialize();
     },
 
     __initialize: function() {
@@ -299,30 +301,23 @@
   Polymer.Base = Polymer.Base.chainObject(Polymer.Base, HTMLElement.prototype);
   Polymer.BaseDescriptors = {};
 
-  if (Polymer.Settings.enableInert) {
+  var disableUpgradePropertySetter;
+  if (Polymer.Settings.disableUpgradeEnabled) {
 
-    var inertPropertySetter = function(property, value) {
-      this.__data__[property] = value;
+    var origAttributeChangedCallback = Polymer.Base.attributeChangedCallback;
+    Polymer.Base.attributeChangedCallback = function(name, oldValue, newValue) {
+      if (!this.__hasInitialized && name === 'disable-upgrade') {
+        this.__hasInitialized = true;
+        this._propertySetter = Polymer.Bind._modelApi._propertySetter;
+        this.__initialize();
+      }
+      origAttributeChangedCallback.call(this, name, oldValue, newValue);
     }
 
-    var inertDesc = {
-      configurable: true,
-      writeable: true,
-      set: function(val) {
-        if (!val && this.isInert) {
-          this.__data__.isInert = false;
-          this._propertySetter = Polymer.Bind._modelApi._propertySetter;
-          this.__initialize();
-          this.removeAttribute('is-inert');
-        }
-      },
-      get: function() {
-        return this.__data__.isInert;
-      }
+    disableUpgradePropertySetter = function(property, value) {
+      this.__data__[property] = value;
     }
 
-    Polymer.BaseDescriptors.isInert = inertDesc;
-    Object.defineProperty(Polymer.Base, 'isInert', inertDesc);
   }
 
   if (window.CustomElements) {
diff --git a/test/runner.html b/test/runner.html
index 0cb45953d9..f44d0a8c9b 100644
--- a/test/runner.html
+++ b/test/runner.html
@@ -93,7 +93,7 @@
       'unit/script-after-import-in-head.html',
       'unit/globals.html',
       'unit/lazy-register.html',
-      'unit/element-inertness.html'
+      'unit/element-disable-upgrade.html'
     ];
 
     if (document.body.createShadowRoot) {
diff --git a/test/unit/element-inertness.html b/test/unit/element-disable-upgrade.html
similarity index 65%
rename from test/unit/element-inertness.html
rename to test/unit/element-disable-upgrade.html
index 882bdb3614..f070c248fe 100644
--- a/test/unit/element-inertness.html
+++ b/test/unit/element-disable-upgrade.html
@@ -11,10 +11,10 @@
 <meta charset="utf-8">
 <script src="../../../webcomponentsjs/webcomponents-lite.js"></script>
 <script src="../../../web-component-tester/browser.js"></script>
-<script>Polymer = {enableInert: true}</script>
+<script>Polymer = {disableUpgradeEnabled: true}</script>
 <link rel="import" href="../../polymer.html">
 
-<dom-module id="x-inert">
+<dom-module id="x-lazy">
   <template>
     <style>
     :host {
@@ -26,7 +26,7 @@
   <script>
   HTMLImports.whenReady(function() {
     Polymer({
-      is: 'x-inert'
+      is: 'x-lazy'
     });
   });
   </script>
@@ -34,7 +34,7 @@
 
 <test-fixture id="simple">
   <template>
-    <x-inert is-inert></x-inert>
+    <x-lazy disable-upgrade></x-lazy>
   </template>
 </test-fixture>
 
@@ -68,14 +68,14 @@
   </script>
 </dom-module>
 
-<dom-module id="x-complicated-inert">
+<dom-module id="x-complicated-lazy">
   <template>
-    <x-complicated-child id="child" a="{{a}}" is-inert="{{b}}" c="{{c}}"></x-complicated-child>
+    <x-complicated-child id="child" a="{{a}}" disable-upgrade$="{{b}}" c="{{c}}"></x-complicated-child>
   </template>
   <script>
   HTMLImports.whenReady(function() {
     Polymer({
-      is: 'x-complicated-inert',
+      is: 'x-complicated-lazy',
       properties: {
         a: {value: true},
         b: {value: true},
@@ -86,20 +86,20 @@
   </script>
 </dom-module>
 
-<test-fixture id="databind-inert">
+<test-fixture id="databind-lazy">
   <template>
-    <x-complicated-inert></x-complicated-inert>
+    <x-complicated-lazy></x-complicated-lazy>
   </template>
 </test-fixture>
 
-<dom-module id="x-complicated-not-inert">
+<dom-module id="x-complicated-not-lazy">
   <template>
-    <x-complicated-child id="child" a="{{a}}" is-inert="{{b}}" c="{{c}}"></x-complicated-child>
+    <x-complicated-child id="child" a="{{a}}" disable-upgrade$="{{b}}" c="{{c}}"></x-complicated-child>
   </template>
   <script>
   HTMLImports.whenReady(function() {
     Polymer({
-      is: 'x-complicated-not-inert',
+      is: 'x-complicated-not-lazy',
       properties: {
         a: {value: true},
         b: {value: false},
@@ -110,40 +110,40 @@
   </script>
 </dom-module>
 
-<test-fixture id="databind-not-inert">
+<test-fixture id="databind-not-lazy">
   <template>
-    <x-complicated-not-inert></x-complicated-not-inert>
+    <x-complicated-not-lazy></x-complicated-not-lazy>
   </template>
 </test-fixture>
 
 <script>
-suite('Element Inertness', function() {
-  suite('Inert', function() {
+suite('Element disableUpgrade', function() {
+  suite('disable-upgrade', function() {
     var el;
     setup(function() {
       el = fixture('simple');
     });
-    test('does not stamp when inert', function() {
-      assert.equal(el.isInert, true);
+    test('does not stamp when lazy', function() {
+      assert.equal(el.hasAttribute('disable-upgrade'), true);
       assert.notOk(el.shadowRoot);
       assert.notOk(el.$);
     });
-    test('stamps when isInert is removed', function() {
-      el.isInert = false;
+    test('stamps when disableUpgrade is removed', function() {
+      el.removeAttribute('disable-upgrade');
       assert.ok(el.root);
       assert.ok(el.$.child);
     });
   });
-  suite('Inertness and Databinding', function() {
-    test('binding to is-inert with true', function() {
-      var el = fixture('databind-inert');
-      assert.equal(el.$.child.isInert, true);
+  suite('disableUpgrade and Databinding', function() {
+    test('binding to disable-upgrade with true', function() {
+      var el = fixture('databind-lazy');
+      assert.equal(el.$.child.hasAttribute('disable-upgrade'), true);
       assert.equal(el.$.child.aRan, undefined);
       assert.equal(el.$.child.cRan, undefined);
     });
-    test('bindings to is-inert with false', function () {
-      var el = fixture('databind-not-inert');
-      assert.notOk(el.$.child.isInert);
+    test('bindings to disable-upgrade with false', function () {
+      var el = fixture('databind-not-lazy');
+      assert.notOk(el.$.child.hasAttribute('disable-upgrade'));
       assert.equal(el.$.child.aRan, true);
       assert.equal(el.$.child.cRan, true);
     })