--- a/toolkit/components/places/tests/unit/xpcshell.ini
+++ b/toolkit/components/places/tests/unit/xpcshell.ini
@@ -69,17 +69,16 @@ skip-if = os == "android"
 [test_analyze.js]
 [test_annotations.js]
 [test_asyncExecuteLegacyQueries.js]
 # Bug 676989: test hangs consistently on Android
 skip-if = os == "android"
 [test_async_history_api.js]
 [test_async_in_batchmode.js]
 [test_async_transactions.js]
-skip-if = (os == "win" && os_version == "5.1") # Bug 1158887
 [test_autocomplete_stopSearch_no_throw.js]
 [test_bookmark_catobs.js]
 [test_bookmarks_json.js]
 [test_bookmarks_html.js]
 [test_bookmarks_html_corrupt.js]
 [test_bookmarks_html_import_tags.js]
 [test_bookmarks_html_singleframe.js]
 [test_bookmarks_restore_notification.js]

--- a/toolkit/content/aboutSupport.js
+++ b/toolkit/content/aboutSupport.js
@@ -57,20 +57,16 @@ var snapshotFormatters = {
       case 1:
       case 2:
       case 4:
       case 6:
       case 7:
       case 8:
         statusText = stringBundle().GetStringFromName("multiProcessStatus." + data.autoStartStatus);
         break;
-
-      case 10:
-        statusText = (Services.appinfo.OS == "Darwin" ? "OS X 10.6 - 10.8" : "Windows XP");
-        break;
     }
 
     $("multiprocess-box").textContent = stringBundle().formatStringFromName("multiProcessWindows",
       [data.numRemoteWindows, data.numTotalWindows, statusText], 3);
 
     $("safemode-box").textContent = data.safeMode;
   },
 

--- a/toolkit/content/tests/chrome/test_bug624329.xul
+++ b/toolkit/content/tests/chrome/test_bug624329.xul
@@ -49,23 +49,21 @@ function childFocused() {
     // maximizing the window is a simple way to ensure that the menu is near
     // the right edge of the screen.
 
     listenOnce("resize", childResized);
     win.maximize();
 }
 
 function childResized() {
-    const isOSXLion = navigator.userAgent.indexOf("Mac OS X 10.7") != -1;
-    const isOSXMtnLion = navigator.userAgent.indexOf("Mac OS X 10.8") != -1;
     const isOSXMavericks = navigator.userAgent.indexOf("Mac OS X 10.9") != -1;
     const isOSXYosemite = navigator.userAgent.indexOf("Mac OS X 10.10") != -1;
-    if (isOSXLion || isOSXMtnLion || isOSXMavericks || isOSXYosemite) {
+    if (isOSXMavericks || isOSXYosemite) {
         todo_is(win.windowState, win.STATE_MAXIMIZED,
-                "A resize before being maximized breaks this test on 10.7 and 10.8 and 10.9 and 10.10");
+                "A resize before being maximized breaks this test on 10.9 and 10.10");
         finish();
         return;
     }
 
     is(win.windowState, win.STATE_MAXIMIZED,
        "window should be maximized");
 
     isnot(win.innerWidth, 300,

--- a/toolkit/mozapps/update/tests/unit_base_updater/xpcshell.ini
+++ b/toolkit/mozapps/update/tests/unit_base_updater/xpcshell.ini
@@ -6,103 +6,81 @@
 # which doesn't use the updater binary as other applications do and are excluded
 # from running the tests in the moz.build file.
 
 [DEFAULT]
 tags = appupdate
 head = head_update.js
 
 [marSuccessComplete.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 [marSuccessPartial.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 [marFailurePartial.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 [marStageSuccessComplete.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 [marStageSuccessPartial.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 [marVersionDowngrade.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985 and mar signing
 [marWrongChannel.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985 and mar signing
 [marStageFailurePartial.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 [marCallbackAppSuccessComplete_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marCallbackAppSuccessPartial_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marCallbackAppStageSuccessComplete_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marCallbackAppStageSuccessPartial_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marAppInUseSuccessComplete.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985 and bug 1164150
 [marAppInUseStageSuccessComplete_unix.js]
 skip-if = os == 'win'
-reason = not a Windows test and bug 1164150
+reason = not a Windows test
 [marAppInUseStageFailureComplete_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marFileLockedFailureComplete_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marFileLockedFailurePartial_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marFileLockedStageFailureComplete_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marFileLockedStageFailurePartial_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marFileInUseSuccessComplete_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marFileInUseSuccessPartial_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marRMRFDirFileInUseSuccessComplete_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marRMRFDirFileInUseSuccessPartial_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marFileInUseStageFailureComplete_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marFileInUseStageFailurePartial_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marRMRFDirFileInUseStageFailureComplete_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marRMRFDirFileInUseStageFailurePartial_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marAppApplyDirLockedStageFailure_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marAppApplyUpdateAppBinInUseStageSuccess_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test
 [marAppApplyUpdateSuccess.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985 and bug 1164150
 [marAppApplyUpdateStageSuccess.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985 and bug 1164150
 [marWrongApplyToDirFailure_win.js]
-skip-if = os != 'win' || debug && (os_version == '5.1' || os_version == '5.2')
-reason = Windows only test and bug 1291985
+skip-if = os != 'win'
+reason = Windows only test

--- a/toolkit/mozapps/update/tests/unit_service_updater/xpcshell.ini
+++ b/toolkit/mozapps/update/tests/unit_service_updater/xpcshell.ini
@@ -4,124 +4,66 @@
 
 # Tests that require the updater binary and the maintenance service.
 
 [DEFAULT]
 tags = appupdate
 head = head_update.js
 
 [bootstrapSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marSuccessCompleteSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marSuccessPartialSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marFailurePartialSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marStageSuccessCompleteSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marStageSuccessPartialSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marStageFailurePartialSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marCallbackAppSuccessCompleteSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marCallbackAppSuccessPartialSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marCallbackAppStageSuccessCompleteSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marCallbackAppStageSuccessPartialSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marAppInUseSuccessCompleteSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marAppInUseStageFailureCompleteSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marFileLockedFailureCompleteSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marFileLockedFailurePartialSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marFileLockedStageFailureCompleteSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marFileLockedStageFailurePartialSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marFileInUseSuccessCompleteSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marFileInUseSuccessPartialSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marRMRFDirFileInUseSuccessCompleteSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marRMRFDirFileInUseSuccessPartialSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marFileInUseStageFailureCompleteSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marFileInUseStageFailurePartialSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marRMRFDirFileInUseStageFailureCompleteSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marRMRFDirFileInUseStageFailurePartialSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marAppApplyDirLockedStageFailureSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marAppApplyUpdateAppBinInUseStageSuccessSvc_win.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marAppApplyUpdateSuccessSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [marAppApplyUpdateStageSuccessSvc.js]
-skip-if = os == 'win' && debug && (os_version == '5.1' || os_version == '5.2')
-reason = bug 1291985
 run-sequentially = Uses the Mozilla Maintenance Service.
 [checkUpdaterSigSvc.js]