--- a/testing/geckodriver/src/prefs.rs
+++ b/testing/geckodriver/src/prefs.rs
@@ -1,12 +1,12 @@
 use mozprofile::preferences::Pref;
 
 lazy_static! {
-    pub static ref DEFAULT: [(&'static str, Pref); 80] = [
+    pub static ref DEFAULT: [(&'static str, Pref); 82] = [
         // Disable automatic downloading of new releases
         ("app.update.auto", Pref::new(false)),
 
         // Disable automatically upgrading Firefox
         ("app.update.enabled", Pref::new(false)),
 
         // Increase the APZ content response timeout in tests to 1
         // minute.  This is to accommodate the fact that test environments
@@ -100,16 +100,24 @@ lazy_static! {
         ("browser.tabs.warnOnOpen", Pref::new(false)),
 
         // Disable first run splash page on Windows 10
         ("browser.usedOnWindows10.introURL", Pref::new("")),
 
         // Disable the UI tour
         ("browser.uitour.enabled", Pref::new(false)),
 
+        // Turn off search suggestions in the location bar so as not to trigger
+        // network connections.
+        ("browser.urlbar.suggest.searches", Pref::new(false)),
+
+        // Turn off the location bar search suggestions opt-in.  It interferes with
+        // tests that don't expect it to be there.
+        ("browser.urlbar.userMadeSearchSuggestionsChoice", Pref::new(true)),
+
         // Do not warn on quitting Firefox
         ("browser.warnOnQuit", Pref::new(false)),
 
         // Do not show datareporting policy notifications which can
         // interfere with tests
         ("datareporting.healthreport.about.reportUrl", Pref::new("http://%(server)s/dummy/abouthealthreport/")),
         ("datareporting.healthreport.documentServerURI", Pref::new("http://%(server)s/dummy/healthreport/")),
         ("datareporting.healthreport.logging.consoleEnabled", Pref::new(false)),

--- a/testing/marionette/client/marionette_driver/geckoinstance.py
+++ b/testing/marionette/client/marionette_driver/geckoinstance.py
@@ -470,16 +470,24 @@ class DesktopInstance(GeckoInstance):
         # Do not warn when closing all other open tabs
         "browser.tabs.warnOnCloseOtherTabs": False,
         # Do not warn when multiple tabs will be opened
         "browser.tabs.warnOnOpen": False,
 
         # Disable the UI tour
         "browser.uitour.enabled": False,
 
+        # Turn off search suggestions in the location bar so as not to trigger network
+        # connections.
+        "browser.urlbar.suggest.searches": False,
+
+        # Turn off the location bar search suggestions opt-in.  It interferes with
+        # tests that don't expect it to be there.
+        "browser.urlbar.userMadeSearchSuggestionsChoice": True,
+
         # Disable first-run welcome page
         "startup.homepage_welcome_url": "about:blank",
         "startup.homepage_welcome_url.additional": "",
     }
 
     def __init__(self, *args, **kwargs):
         super(DesktopInstance, self).__init__(*args, **kwargs)
         self.required_prefs.update(DesktopInstance.desktop_prefs)

--- a/testing/marionette/server.js
+++ b/testing/marionette/server.js
@@ -157,16 +157,24 @@ const RECOMMENDED_PREFS = new Map([
   // Disable first run splash page on Windows 10
   ["browser.usedOnWindows10.introURL", ""],
 
   // Disable the UI tour.
   //
   // Should be set in profile.
   ["browser.uitour.enabled", false],
 
+  // Turn off search suggestions in the location bar so as not to trigger
+  // network connections.
+  ["browser.urlbar.suggest.searches", false],
+
+  // Turn off the location bar search suggestions opt-in.  It interferes with
+  // tests that don't expect it to be there.
+  ["browser.urlbar.userMadeSearchSuggestionsChoice", true],
+
   // Do not show datareporting policy notifications which can
   // interfere with tests
   [
     "datareporting.healthreport.about.reportUrl",
     "http://%(server)s/dummy/abouthealthreport/",
   ],
   [
     "datareporting.healthreport.documentServerURI",