diff --git a/toolkit/mozapps/update/test/unit/test_0200_app_launch_apply_update.js b/toolkit/mozapps/update/test/unit/test_0200_app_launch_apply_update.js
index 2a9cd78a566..5d5dffd1738 100644
--- a/toolkit/mozapps/update/test/unit/test_0200_app_launch_apply_update.js
+++ b/toolkit/mozapps/update/test/unit/test_0200_app_launch_apply_update.js
@@ -18,12 +18,16 @@ const FILE_UPDATER_INI_BAK = "updater.ini.bak";
 // Number of milliseconds for each do_timeout call.
 const CHECK_TIMEOUT_MILLI = 1000;
 
+// How many of CHECK_TIMEOUT_MILLI to wait before we abort the test.
+const MAX_TIMEOUT_RUNS = 300;
+
 // Maximum number of milliseconds the process that is launched can run before
 // the test will try to kill it.
 const APP_TIMER_TIMEOUT = 15000;
 
 let gAppTimer;
 let gProcess;
+let gTimeoutRuns = 0;
 
 function run_test() {
   do_test_pending();
@@ -236,19 +240,26 @@ function getUpdateTestDir() {
  * the test.
  */
 function checkUpdateFinished() {
+  gTimeoutRuns++;
   // Don't proceed until the update.log has been created.
   let log = getUpdatesDir();
   log.append("0");
   log.append(FILE_UPDATE_LOG);
   if (!log.exists()) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+    if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded MAX_TIMEOUT_RUNS whilst waiting for updates log to be created");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
     return;
   }
 
   // Don't proceed until the update status is no longer pending or applying.
   let status = readStatusFile();
   if (status == STATE_PENDING || status == STATE_APPLYING) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+    if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded MAX_TIMEOUT_RUNS whilst waiting for updates status to not be pending or applying");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
     return;
   }
 
diff --git a/toolkit/mozapps/update/test/unit/test_0201_app_launch_apply_update.js b/toolkit/mozapps/update/test/unit/test_0201_app_launch_apply_update.js
index 74b7a0a3c08..8b68250d08d 100644
--- a/toolkit/mozapps/update/test/unit/test_0201_app_launch_apply_update.js
+++ b/toolkit/mozapps/update/test/unit/test_0201_app_launch_apply_update.js
@@ -21,6 +21,9 @@ const FILE_UPDATER_INI_BAK = "updater.ini.bak";
 // Number of milliseconds for each do_timeout call.
 const CHECK_TIMEOUT_MILLI = 1000;
 
+// How many of CHECK_TIMEOUT_MILLI to wait before we abort the test.
+const MAX_TIMEOUT_RUNS = 300;
+
 // Maximum number of milliseconds the process that is launched can run before
 // the test will try to kill it.
 const APP_TIMER_TIMEOUT = 15000;
@@ -28,6 +31,7 @@ const APP_TIMER_TIMEOUT = 15000;
 let gAppTimer;
 let gProcess;
 let gActiveUpdate;
+let gTimeoutRuns = 0;
 
 // Override getUpdatesRootDir on Mac because we need to apply the update
 // inside the bundle directory.
@@ -327,9 +331,13 @@ function getUpdateTestDir() {
  * Checks if the update has finished being applied in the background.
  */
 function checkUpdateApplied() {
+  gTimeoutRuns++;
   // Don't proceed until the update has been applied.
   if (gUpdateManager.activeUpdate.state != STATE_APPLIED_PLATFORM) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
+    if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded MAX_TIMEOUT_RUNS whilst waiting for update to be applied");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
     return;
   }
 
@@ -459,11 +467,15 @@ function checkUpdateApplied() {
  * the test.
  */
 function checkUpdateFinished() {
+  gTimeoutRuns++;
   // Don't proceed until the update status is no longer applied.
   try {
     let status = readStatusFile();
     if (status != STATE_SUCCEEDED) {
-      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+      if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+        do_throw("Exceeded MAX_TIMEOUT_RUNS whilst waiting for succeeded state");
+      else
+        do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
       return;
     }
   } catch (e) {
@@ -477,7 +489,10 @@ function checkUpdateFinished() {
     if (e.result == Components.results.NS_ERROR_FILE_IS_LOCKED) {
       // This might happen on Windows in case the callback application has not
       // finished its job yet.  So, we'll wait some more.
-      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+      if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+        do_throw("Exceeded whilst waiting for file to be unlocked");
+      else
+        do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
       return;
     } else {
       do_throw("getAppConsoleLogPath threw: " + e);
@@ -493,7 +508,10 @@ function checkUpdateFinished() {
   updatedDir.append(UPDATED_DIR_SUFFIX.replace("/", ""));
   logTestInfo("testing " + updatedDir.path + " shouldn't exist");
   if (updatedDir.exists()) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+    if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded whilst waiting for update dir to not exist");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
     return;
   }
 
diff --git a/toolkit/mozapps/update/test/unit/test_0203_app_launch_apply_update.js b/toolkit/mozapps/update/test/unit/test_0203_app_launch_apply_update.js
index 16f57d09775..43b18288a5e 100644
--- a/toolkit/mozapps/update/test/unit/test_0203_app_launch_apply_update.js
+++ b/toolkit/mozapps/update/test/unit/test_0203_app_launch_apply_update.js
@@ -27,6 +27,8 @@ const FILE_UPDATER_INI_BAK = "updater.ini.bak";
 // Number of milliseconds for each do_timeout call.
 const CHECK_TIMEOUT_MILLI = 1000;
 
+const MAX_TIMEOUT_RUNS = 300;
+
 // Maximum number of milliseconds the process that is launched can run before
 // the test will try to kill it.
 const APP_TIMER_TIMEOUT = 15000;
@@ -36,6 +38,7 @@ Components.utils.import("resource://gre/modules/ctypes.jsm");
 let gAppTimer;
 let gProcess;
 let gActiveUpdate;
+let gTimeoutRuns = 0;
 
 // Override getUpdatesRootDir on Mac because we need to apply the update
 // inside the bundle directory.
@@ -356,9 +359,13 @@ function getUpdateTestDir() {
  * Checks if the update has finished being applied in the background.
  */
 function checkUpdateApplied() {
+  gTimeoutRuns++;
   // Don't proceed until the update has been applied.
   if (gUpdateManager.activeUpdate.state != STATE_APPLIED_PLATFORM) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
+    if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded whilst waiting for update to be applied");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
     return;
   }
 
@@ -489,10 +496,14 @@ function checkUpdateApplied() {
  */
 function checkUpdateFinished() {
   // Don't proceed until the update status is no longer applied.
+  gTimeoutRuns++;
   try {
     let status = readStatusFile();
     if (status != STATE_SUCCEEDED) {
-      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+      if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+        do_throw("Exceeded whilst waiting for succeeded state");
+      else
+        do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
       return;
     }
   } catch (e) {
@@ -506,7 +517,10 @@ function checkUpdateFinished() {
     if (e.result == Components.results.NS_ERROR_FILE_IS_LOCKED) {
       // This might happen on Windows in case the callback application has not
       // finished its job yet.  So, we'll wait some more.
-      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+      if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+        do_throw("Exceeded whilst waiting for file to be unlocked");
+      else
+        do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
       return;
     } else {
       do_throw("getAppConsoleLogPath threw: " + e);
diff --git a/toolkit/mozapps/update/test_svc/unit/test_0200_app_launch_apply_update_svc.js b/toolkit/mozapps/update/test_svc/unit/test_0200_app_launch_apply_update_svc.js
index 1c9ffedb312..ab25c45f2b2 100644
--- a/toolkit/mozapps/update/test_svc/unit/test_0200_app_launch_apply_update_svc.js
+++ b/toolkit/mozapps/update/test_svc/unit/test_0200_app_launch_apply_update_svc.js
@@ -18,10 +18,15 @@ const FILE_UPDATER_INI_BAK = "updater.ini.bak";
 // Number of milliseconds for each do_timeout call.
 const CHECK_TIMEOUT_MILLI = 1000;
 
+// How many of CHECK_TIMEOUT_MILLI to wait before we abort the test.
+const MAX_TIMEOUT_RUNS = 300;
+
 // Maximum number of milliseconds the process that is launched can run before
 // the test will try to kill it.
 const APP_TIMER_TIMEOUT = 15000;
 
+let gTimeoutRuns = 0;
+
 function run_test() {
   if (!shouldRunServiceTest()) {
     return;
@@ -198,7 +203,10 @@ function checkUpdateFinished() {
   log.append("0");
   log.append(FILE_UPDATE_LOG);
   if (!log.exists()) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+    if (++gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded MAX_TIMEOUT_RUNS whilst waiting for updates log to be created");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
     return;
   }
 
diff --git a/toolkit/mozapps/update/test_svc/unit/test_0201_app_launch_apply_update_svc.js b/toolkit/mozapps/update/test_svc/unit/test_0201_app_launch_apply_update_svc.js
index 73e9c04fc45..a44ba361098 100644
--- a/toolkit/mozapps/update/test_svc/unit/test_0201_app_launch_apply_update_svc.js
+++ b/toolkit/mozapps/update/test_svc/unit/test_0201_app_launch_apply_update_svc.js
@@ -21,6 +21,9 @@ const FILE_UPDATER_INI_BAK = "updater.ini.bak";
 // Number of milliseconds for each do_timeout call.
 const CHECK_TIMEOUT_MILLI = 1000;
 
+// How many of CHECK_TIMEOUT_MILLI to wait before we abort the test.
+const MAX_TIMEOUT_RUNS = 300;
+
 // Maximum number of milliseconds the process that is launched can run before
 // the test will try to kill it.
 const APP_TIMER_TIMEOUT = 15000;
@@ -28,6 +31,7 @@ const APP_TIMER_TIMEOUT = 15000;
 let gAppTimer;
 let gProcess;
 let gActiveUpdate;
+let gTimeoutRuns = 0;
 
 // Override getUpdatesRootDir on Mac because we need to apply the update
 // inside the bundle directory.
@@ -335,9 +339,13 @@ function getUpdateTestDir() {
  * Checks if the update has finished being applied in the background.
  */
 function checkUpdateApplied() {
+  gTimeoutRuns++;
   // Don't proceed until the update has been applied.
   if (gUpdateManager.activeUpdate.state != STATE_APPLIED_PLATFORM) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
+    if (++gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded MAX_TIMEOUT_RUNS whilst waiting for state to be applied to platform");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
     return;
   }
 
@@ -352,7 +360,10 @@ function checkUpdateApplied() {
   let log = getUpdatesDir();
   log.append(FILE_LAST_LOG);
   if (!log.exists()) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
+    if (++gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded MAX_TIMEOUT_RUNS whilst waiting for update log to be created");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
     return;
   }
 
@@ -439,11 +450,15 @@ function checkUpdateApplied() {
  * the test.
  */
 function checkUpdateFinished() {
+  gTimeoutRuns++;
   // Don't proceed until the update status is no longer applied.
   try {
     let status = readStatusFile();
     if (status != STATE_SUCCEEDED) {
-      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+      if (++gTimeoutRuns > MAX_TIMEOUT_RUNS)
+        do_throw("Exceeded MAX_TIMEOUT_RUNS whist waiting for succeeded state");
+      else
+        do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
       return;
     }
   } catch (e) {
@@ -457,7 +472,10 @@ function checkUpdateFinished() {
     if (e.result == Components.results.NS_ERROR_FILE_IS_LOCKED) {
       // This might happen on Windows in case the callback application has not
       // finished its job yet.  So, we'll wait some more.
-      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+      if (++gTimeoutRuns > MAX_TIMEOUT_RUNS)
+        do_throw("Exceeded whilst waiting for file to be unlocked");
+      else
+        do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
       return;
     } else {
       do_throw("getAppConsoleLogPath threw: " + e);
diff --git a/toolkit/mozapps/update/test_svc/unit/test_0202_app_launch_apply_update_dirlocked_svc.js b/toolkit/mozapps/update/test_svc/unit/test_0202_app_launch_apply_update_dirlocked_svc.js
index 021533c10f5..7f58b9b2fa1 100644
--- a/toolkit/mozapps/update/test_svc/unit/test_0202_app_launch_apply_update_dirlocked_svc.js
+++ b/toolkit/mozapps/update/test_svc/unit/test_0202_app_launch_apply_update_dirlocked_svc.js
@@ -27,11 +27,15 @@ const FILE_UPDATER_INI_BAK = "updater.ini.bak";
 // Number of milliseconds for each do_timeout call.
 const CHECK_TIMEOUT_MILLI = 1000;
 
+// How many of CHECK_TIMEOUT_MILLI to wait before we abort the test.
+const MAX_TIMEOUT_RUNS = 300;
+
 // Maximum number of milliseconds the process that is launched can run before
 // the test will try to kill it.
 const APP_TIMER_TIMEOUT = 15000;
 
 let gActiveUpdate;
+let gTimeoutRuns = 0;
 
 // Override getUpdatesRootDir on Mac because we need to apply the update
 // inside the bundle directory.
@@ -300,7 +304,10 @@ function getUpdateTestDir() {
 function checkUpdateApplied() {
   // Don't proceed until the update has failed, and reset to pending.
   if (gUpdateManager.activeUpdate.state != STATE_PENDING) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
+    if (++gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded MAX_TIMEOUT_RUNS whist waiting for pending state to finish");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
     return;
   }
 
diff --git a/toolkit/mozapps/update/test_svc/unit/test_0203_app_launch_apply_update_svc.js b/toolkit/mozapps/update/test_svc/unit/test_0203_app_launch_apply_update_svc.js
index 97e0a1c6aaa..a8d2735b805 100644
--- a/toolkit/mozapps/update/test_svc/unit/test_0203_app_launch_apply_update_svc.js
+++ b/toolkit/mozapps/update/test_svc/unit/test_0203_app_launch_apply_update_svc.js
@@ -27,6 +27,9 @@ const FILE_UPDATER_INI_BAK = "updater.ini.bak";
 // Number of milliseconds for each do_timeout call.
 const CHECK_TIMEOUT_MILLI = 1000;
 
+// How many of CHECK_TIMEOUT_MILLI to wait before we abort the test.
+const MAX_TIMEOUT_RUNS = 300;
+
 // Maximum number of milliseconds the process that is launched can run before
 // the test will try to kill it.
 const APP_TIMER_TIMEOUT = 15000;
@@ -36,6 +39,7 @@ Components.utils.import("resource://gre/modules/ctypes.jsm");
 let gAppTimer;
 let gProcess;
 let gActiveUpdate;
+let gTimeoutRuns = 0;
 
 // Override getUpdatesRootDir on Mac because we need to apply the update
 // inside the bundle directory.
@@ -364,9 +368,13 @@ function getUpdateTestDir() {
  * Checks if the update has finished being applied in the background.
  */
 function checkUpdateApplied() {
+  gTimeoutRuns++;
   // Don't proceed until the update has been applied.
   if (gUpdateManager.activeUpdate.state != STATE_APPLIED_PLATFORM) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
+    if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded MAX_TIMEOUT_RUNS whist waiting for update to be applied to the platform");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
     return;
   }
 
@@ -381,7 +389,10 @@ function checkUpdateApplied() {
   let log = getUpdatesDir();
   log.append(FILE_LAST_LOG);
   if (!log.exists()) {
-    do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
+    if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+      do_throw("Exceeded MAX_TIMEOUT_RUNS whist waiting for update log to be created");
+    else
+      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateApplied);
     return;
   }
 
@@ -468,11 +479,15 @@ function checkUpdateApplied() {
  * the test.
  */
 function checkUpdateFinished() {
+  gTimeoutRuns++;
   // Don't proceed until the update status is no longer applied.
   try {
     let status = readStatusFile();
     if (status != STATE_SUCCEEDED) {
-      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+      if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+        do_throw("Exceeded MAX_TIMEOUT_RUNS whist waiting for success status");
+      else
+        do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
       return;
     }
   } catch (e) {
@@ -484,9 +499,12 @@ function checkUpdateFinished() {
     getAppConsoleLogPath();
   } catch (e) {
     if (e.result == Components.results.NS_ERROR_FILE_IS_LOCKED) {
-      // This might happen on Windows in case the callback application has not
-      // finished its job yet.  So, we'll wait some more.
-      do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
+      if (gTimeoutRuns > MAX_TIMEOUT_RUNS)
+        do_throw("Exceeded MAX_TIMEOUT_RUNS whist waiting for file to be unlocked");
+      else
+        // This might happen on Windows in case the callback application has not
+        // finished its job yet.  So, we'll wait some more.
+        do_timeout(CHECK_TIMEOUT_MILLI, checkUpdateFinished);
       return;
     } else {
       do_throw("getAppConsoleLogPath threw: " + e);