--- a/browser/base/content/test/performance/browser.ini
+++ b/browser/base/content/test/performance/browser.ini
@@ -10,13 +10,15 @@ skip-if = !e10s
 skip-if = !debug
 [browser_tabclose_grow_reflows.js]
 [browser_tabclose_reflows.js]
 [browser_tabopen_reflows.js]
 [browser_tabopen_squeeze_reflows.js]
 [browser_tabstrip_overflow_underflow_reflows.js]
 [browser_tabswitch_reflows.js]
 [browser_toolbariconcolor_restyles.js]
+[browser_urlbar_keyed_search_reflows.js]
+skip-if = (os == 'linux') || (os == 'win' && debug) # Disabled on Linux and Windows debug due to perma failures. Bug 1392320.
 [browser_urlbar_search_reflows.js]
 skip-if = (os == 'linux') || (os == 'mac' && !debug) # Disabled on Linux and OS X opt due to frequent failures. Bug 1385932 and Bug 1384582
 [browser_windowclose_reflows.js]
 [browser_windowopen_reflows.js]
 skip-if = os == 'linux' # Disabled due to frequent failures. Bug 1380465.

new file mode 100644
--- /dev/null
+++ b/browser/base/content/test/performance/browser_urlbar_keyed_search_reflows.js
@@ -0,0 +1,183 @@
+"use strict";
+
+// There are a _lot_ of reflows in this test, and processing them takes
+// time. On slower builds, we need to boost our allowed test time.
+requestLongerTimeout(5);
+
+/**
+ * WHOA THERE: We should never be adding new things to EXPECTED_REFLOWS. This
+ * is a whitelist that should slowly go away as we improve the performance of
+ * the front-end. Instead of adding more reflows to the whitelist, you should
+ * be modifying your code to avoid the reflow.
+ *
+ * See https://developer.mozilla.org/en-US/Firefox/Performance_best_practices_for_Firefox_fe_engineers
+ * for tips on how to do that.
+ */
+
+/* These reflows happen only the first time the awesomebar panel opens. */
+const EXPECTED_REFLOWS_FIRST_OPEN = [
+  // Bug 1357054
+  {
+    stack: [
+      "_rebuild@chrome://browser/content/search/search.xml",
+      "set_popup@chrome://browser/content/search/search.xml",
+      "enableOneOffSearches@chrome://browser/content/urlbarBindings.xml",
+      "_enableOrDisableOneOffSearches@chrome://browser/content/urlbarBindings.xml",
+      "urlbar_XBL_Constructor/<@chrome://browser/content/urlbarBindings.xml",
+      "openPopup@chrome://global/content/bindings/popup.xml",
+      "_openAutocompletePopup@chrome://browser/content/urlbarBindings.xml",
+      "openAutocompletePopup@chrome://browser/content/urlbarBindings.xml",
+      "openPopup@chrome://global/content/bindings/autocomplete.xml",
+      "set_popupOpen@chrome://global/content/bindings/autocomplete.xml"
+    ],
+    times: 1, // This number should only ever go down - never up.
+  },
+
+  {
+    stack: [
+      "adjustHeight@chrome://global/content/bindings/autocomplete.xml",
+      "onxblpopupshown@chrome://global/content/bindings/autocomplete.xml"
+    ],
+    times: 5, // This number should only ever go down - never up.
+  },
+
+  {
+    stack: [
+      "_handleOverflow@chrome://global/content/bindings/autocomplete.xml",
+      "handleOverUnderflow@chrome://global/content/bindings/autocomplete.xml",
+      "set_siteIconStart@chrome://global/content/bindings/autocomplete.xml",
+    ],
+    times: 6, // This number should only ever go down - never up.
+  },
+
+  {
+    stack: [
+      "adjustHeight@chrome://global/content/bindings/autocomplete.xml",
+      "_invalidate/this._adjustHeightTimeout<@chrome://global/content/bindings/autocomplete.xml",
+    ],
+    times: 36, // This number should only ever go down - never up.
+  },
+
+  {
+    stack: [
+      "_handleOverflow@chrome://global/content/bindings/autocomplete.xml",
+      "handleOverUnderflow@chrome://global/content/bindings/autocomplete.xml",
+      "_reuseAcItem@chrome://global/content/bindings/autocomplete.xml",
+      "_appendCurrentResult@chrome://global/content/bindings/autocomplete.xml",
+      "_invalidate@chrome://global/content/bindings/autocomplete.xml",
+      "invalidate@chrome://global/content/bindings/autocomplete.xml"
+    ],
+    times: 1584, // This number should only ever go down - never up.
+  },
+
+  {
+    stack: [
+      "_handleOverflow@chrome://global/content/bindings/autocomplete.xml",
+      "handleOverUnderflow@chrome://global/content/bindings/autocomplete.xml",
+      "_onChanged@chrome://global/content/bindings/autocomplete.xml",
+      "_appendCurrentResult/<@chrome://global/content/bindings/autocomplete.xml",
+    ],
+    times: 6,
+  },
+
+  {
+    stack: [
+      "_openAutocompletePopup@chrome://browser/content/urlbarBindings.xml",
+      "openAutocompletePopup@chrome://browser/content/urlbarBindings.xml",
+      "openPopup@chrome://global/content/bindings/autocomplete.xml",
+      "set_popupOpen@chrome://global/content/bindings/autocomplete.xml",
+    ],
+    times: 3, // This number should only ever go down - never up.
+  },
+
+  // Bug 1359989
+  {
+    stack: [
+      "openPopup@chrome://global/content/bindings/popup.xml",
+      "_openAutocompletePopup@chrome://browser/content/urlbarBindings.xml",
+      "openAutocompletePopup@chrome://browser/content/urlbarBindings.xml",
+      "openPopup@chrome://global/content/bindings/autocomplete.xml",
+      "set_popupOpen@chrome://global/content/bindings/autocomplete.xml",
+    ],
+  },
+];
+
+/**
+ * Returns a Promise that resolves once the AwesomeBar popup for a particular
+ * window has appeared after having done a search for its input text.
+ *
+ * @param win (browser window)
+ *        The window to do the search in.
+ * @returns Promise
+ */
+async function promiseSearchComplete(win) {
+  let URLBar = win.gURLBar;
+  if (URLBar.popup.state != "open") {
+    await BrowserTestUtils.waitForEvent(URLBar.popup, "popupshown");
+  }
+  await BrowserTestUtils.waitForCondition(() => {
+    return URLBar.controller.searchStatus >=
+      Ci.nsIAutoCompleteController.STATUS_COMPLETE_NO_MATCH;
+  });
+
+  // There are several setTimeout(fn, 0); calls inside autocomplete.xml
+  // that we need to wait for. Since those have higher priority than
+  // idle callbacks, we can be sure they will have run once this
+  // idle callback is called. The timeout seems to be required in
+  // automation - presumably because the machines can be pretty busy
+  // especially if it's GC'ing from previous tests.
+  await new Promise(resolve => win.requestIdleCallback(resolve, { timeout: 1000 }));
+}
+
+add_task(async function setup() {
+  await addDummyHistoryEntries();
+});
+
+/**
+ * This test ensures that there are no unexpected uninterruptible reflows when
+ * typing into the URL bar with the default values in Places.
+ */
+add_task(async function() {
+  let win = await BrowserTestUtils.openNewBrowserWindow();
+  await ensureNoPreloadedBrowser(win);
+
+  let URLBar = win.gURLBar;
+  let popup = URLBar.popup;
+
+  URLBar.focus();
+  URLBar.value = "";
+
+  await withReflowObserver(async function(dirtyFrameFn) {
+    let oldInvalidate = popup.invalidate.bind(popup);
+    let oldResultsAdded = popup.onResultsAdded.bind(popup);
+
+    // We need to invalidate the frame tree outside of the normal
+    // mechanism since invalidations and result additions to the
+    // URL bar occur without firing JS events (which is how we
+    // normally know to dirty the frame tree).
+    popup.invalidate = (reason) => {
+      dirtyFrameFn();
+      oldInvalidate(reason);
+    };
+
+    popup.onResultsAdded = () => {
+      dirtyFrameFn();
+      oldResultsAdded();
+    };
+
+    // Only keying in 6 characters because the number of reflows triggered
+    // is so high that we risk timing out the test if we key in any more.
+    const SEARCH_TERM = "ows-10";
+    for (let i = 0; i < SEARCH_TERM.length; ++i) {
+      let char = SEARCH_TERM[i];
+      EventUtils.synthesizeKey(char, {}, win);
+      await promiseSearchComplete(win);
+    }
+
+    let hiddenPromise = BrowserTestUtils.waitForEvent(URLBar.popup, "popuphidden");
+    EventUtils.synthesizeKey("VK_ESCAPE", {}, win);
+    await hiddenPromise;
+  }, EXPECTED_REFLOWS_FIRST_OPEN, win);
+
+  await BrowserTestUtils.closeWindow(win);
+});

--- a/browser/base/content/test/performance/browser_urlbar_search_reflows.js
+++ b/browser/base/content/test/performance/browser_urlbar_search_reflows.js
@@ -1,17 +1,14 @@
 "use strict";
 
 // There are a _lot_ of reflows in this test, and processing them takes
 // time. On slower builds, we need to boost our allowed test time.
 requestLongerTimeout(5);
 
-XPCOMUtils.defineLazyModuleGetter(this, "PlacesTestUtils",
-                                  "resource://testing-common/PlacesTestUtils.jsm");
-
 /**
  * WHOA THERE: We should never be adding new things to EXPECTED_REFLOWS. This
  * is a whitelist that should slowly go away as we improve the performance of
  * the front-end. Instead of adding more reflows to the whitelist, you should
  * be modifying your code to avoid the reflow.
  *
  * See https://developer.mozilla.org/en-US/Firefox/Performance_best_practices_for_Firefox_fe_engineers
  * for tips on how to do that.
@@ -143,69 +140,20 @@ const EXPECTED_REFLOWS_SECOND_OPEN = [
       "_openAutocompletePopup@chrome://browser/content/urlbarBindings.xml",
       "openAutocompletePopup@chrome://browser/content/urlbarBindings.xml",
       "openPopup@chrome://global/content/bindings/autocomplete.xml",
       "set_popupOpen@chrome://global/content/bindings/autocomplete.xml",
     ],
   },
 ];
 
-/**
- * Returns a Promise that resolves once the AwesomeBar popup for a particular
- * window has appeared after having done a search for its input text.
- *
- * @param win (browser window)
- *        The window to do the search in.
- * @returns Promise
- */
-async function promiseAutocompleteResultPopup(win) {
-  let URLBar = win.gURLBar;
-  URLBar.controller.startSearch(URLBar.value);
-  await BrowserTestUtils.waitForEvent(URLBar.popup, "popupshown");
-  await BrowserTestUtils.waitForCondition(() => {
-    return URLBar.controller.searchStatus >=
-      Ci.nsIAutoCompleteController.STATUS_COMPLETE_NO_MATCH;
-  });
-  let matchCount = URLBar.popup._matchCount;
-  await BrowserTestUtils.waitForCondition(() => {
-    return URLBar.popup.richlistbox.childNodes.length == matchCount;
-  });
-
-  URLBar.controller.stopSearch();
-  // There are several setTimeout(fn, 0); calls inside autocomplete.xml
-  // that we need to wait for. Since those have higher priority than
-  // idle callbacks, we can be sure they will have run once this
-  // idle callback is called. The timeout seems to be required in
-  // automation - presumably because the machines can be pretty busy
-  // especially if it's GC'ing from previous tests.
-  await new Promise(resolve => win.requestIdleCallback(resolve, { timeout: 1000 }));
-
-  let hiddenPromise = BrowserTestUtils.waitForEvent(URLBar.popup, "popuphidden");
-  EventUtils.synthesizeKey("VK_ESCAPE", {}, win);
-  await hiddenPromise;
-}
-
 const SEARCH_TERM = "urlbar-reflows";
 
 add_task(async function setup() {
-  const NUM_VISITS = 10;
-  let visits = [];
-
-  for (let i = 0; i < NUM_VISITS; ++i) {
-    visits.push({
-      uri: `http://example.com/urlbar-reflows-${i}`,
-      title: `Reflow test for URL bar entry #${i}`,
-    });
-  }
-
-  await PlacesTestUtils.addVisits(visits);
-
-  registerCleanupFunction(async function() {
-    await PlacesTestUtils.clearHistory();
-  });
+  await addDummyHistoryEntries();
 });
 
 /**
  * This test ensures that there are no unexpected
  * uninterruptible reflows when typing into the URL bar
  * with the default values in Places.
  */
 add_task(async function() {
@@ -230,17 +178,39 @@ add_task(async function() {
       oldInvalidate(reason);
     };
 
     popup.onResultsAdded = () => {
       dirtyFrameFn();
       oldResultsAdded();
     };
 
-    await promiseAutocompleteResultPopup(win);
+    URLBar.controller.startSearch(URLBar.value);
+    await BrowserTestUtils.waitForEvent(URLBar.popup, "popupshown");
+    await BrowserTestUtils.waitForCondition(() => {
+      return URLBar.controller.searchStatus >=
+        Ci.nsIAutoCompleteController.STATUS_COMPLETE_NO_MATCH;
+    });
+    let matchCount = URLBar.popup._matchCount;
+    await BrowserTestUtils.waitForCondition(() => {
+      return URLBar.popup.richlistbox.childNodes.length == matchCount;
+    });
+
+    URLBar.controller.stopSearch();
+    // There are several setTimeout(fn, 0); calls inside autocomplete.xml
+    // that we need to wait for. Since those have higher priority than
+    // idle callbacks, we can be sure they will have run once this
+    // idle callback is called. The timeout seems to be required in
+    // automation - presumably because the machines can be pretty busy
+    // especially if it's GC'ing from previous tests.
+    await new Promise(resolve => win.requestIdleCallback(resolve, { timeout: 1000 }));
+
+    let hiddenPromise = BrowserTestUtils.waitForEvent(URLBar.popup, "popuphidden");
+    EventUtils.synthesizeKey("VK_ESCAPE", {}, win);
+    await hiddenPromise;
   };
 
   await withReflowObserver(testFn, EXPECTED_REFLOWS_FIRST_OPEN, win);
 
   await withReflowObserver(testFn, EXPECTED_REFLOWS_SECOND_OPEN, win);
 
   await BrowserTestUtils.closeWindow(win);
 });

--- a/browser/base/content/test/performance/head.js
+++ b/browser/base/content/test/performance/head.js
@@ -1,8 +1,13 @@
+"use strict";
+
+XPCOMUtils.defineLazyModuleGetter(this, "PlacesTestUtils",
+  "resource://testing-common/PlacesTestUtils.jsm");
+
 /**
  * Async utility function for ensuring that no unexpected uninterruptible
  * reflows occur during some period of time in a window.
  *
  * @param testFn (async function)
  *        The async function that will exercise the browser activity that is
  *        being tested for reflows.
  *
@@ -87,16 +92,22 @@ async function withReflowObserver(testFn
       dirtyFrameFn();
 
       // Stack trace is empty. Reflow was triggered by native code, which
       // we ignore.
       if (path === "") {
         return;
       }
 
+      // synthesizeKey from EventUtils.js causes us to reflow. That's the test
+      // harness and we don't care about that, so we'll filter that out.
+      if (path.startsWith("synthesizeKey@chrome://mochikit/content/tests/SimpleTest/EventUtils.js")) {
+        return;
+      }
+
       let index = expectedReflows.findIndex(reflow => path.startsWith(reflow.stack.join("|")));
 
       if (index != -1) {
         Assert.ok(true, "expected uninterruptible reflow: '" +
                   JSON.stringify(pathWithLineNumbers, null, "\t") + "'");
         if (--expectedReflows[index].times == 0) {
           expectedReflows.splice(index, 1);
         }
@@ -219,8 +230,30 @@ async function createTabs(howMany) {
 async function removeAllButFirstTab() {
   await SpecialPowers.pushPrefEnv({
     set: [["browser.tabs.warnOnCloseOtherTabs", false]],
   });
   gBrowser.removeAllTabsBut(gBrowser.tabs[0]);
   await BrowserTestUtils.waitForCondition(() => gBrowser.tabs.length == 1);
   await SpecialPowers.popPrefEnv();
 }
+
+/**
+ * Adds some entries to the Places database so that we can
+ * do semi-realistic look-ups in the URL bar.
+ */
+async function addDummyHistoryEntries() {
+  const NUM_VISITS = 10;
+  let visits = [];
+
+  for (let i = 0; i < NUM_VISITS; ++i) {
+    visits.push({
+      uri: `http://example.com/urlbar-reflows-${i}`,
+      title: `Reflow test for URL bar entry #${i}`,
+    });
+  }
+
+  await PlacesTestUtils.addVisits(visits);
+
+  registerCleanupFunction(async function() {
+    await PlacesTestUtils.clearHistory();
+  });
+}