diff --git a/lib/classes/task/search_index_task.php b/lib/classes/task/search_index_task.php
index 7b6f8011d6a..31e742c21d8 100644
--- a/lib/classes/task/search_index_task.php
+++ b/lib/classes/task/search_index_task.php
@@ -51,7 +51,22 @@ class search_index_task extends scheduled_task {
         }
         $globalsearch = \core_search\manager::instance();
 
-        // Indexing database records for modules + rich documents of forum.
-        $globalsearch->index(false, get_config('core', 'searchindextime'), new \text_progress_trace());
+        // Get total indexing time limit.
+        $timelimit = get_config('core', 'searchindextime');
+        $start = time();
+
+        // Do normal indexing.
+        $globalsearch->index(false, $timelimit, new \text_progress_trace());
+
+        // Do requested indexing (if any) for the rest of the time.
+        if ($timelimit != 0) {
+            $now = time();
+            $timelimit -= ($now - $start);
+            if ($timelimit <= 1) {
+                // There is hardly any time left, so don't try to do requests.
+                return;
+            }
+        }
+        $globalsearch->process_index_requests($timelimit, new \text_progress_trace());
     }
 }
diff --git a/search/classes/manager.php b/search/classes/manager.php
index e8a43a84907..4e85cc7c771 100644
--- a/search/classes/manager.php
+++ b/search/classes/manager.php
@@ -1087,4 +1087,78 @@ class manager {
                 'timerequested' => time(), 'partialarea' => '', 'partialtime' => 0 ];
         $DB->insert_record('search_index_requests', $newrecord);
     }
+
+    /**
+     * Processes outstanding index requests. This will take the first item from the queue and
+     * process it, continuing until an optional time limit is reached.
+     *
+     * If there are no index requests, the function will do nothing.
+     *
+     * @param float $timelimit Time limit (0 = none)
+     * @param \progress_trace|null $progress Optional progress indicator
+     */
+    public function process_index_requests($timelimit = 0.0, \progress_trace $progress = null) {
+        global $DB;
+
+        if (!$progress) {
+            $progress = new \null_progress_trace();
+        }
+
+        $complete = false;
+        $before = microtime(true);
+        if ($timelimit) {
+            $stopat = $before + $timelimit;
+        }
+        while (true) {
+            // Retrieve first request, using fully defined ordering.
+            $requests = $DB->get_records('search_index_requests', null,
+                    'timerequested, contextid, searcharea',
+                    'id, contextid, searcharea, partialarea, partialtime', 0, 1);
+            if (!$requests) {
+                // If there are no more requests, stop.
+                $complete = true;
+                break;
+            }
+            $request = reset($requests);
+
+            // Calculate remaining time.
+            $remainingtime = 0;
+            $beforeindex = microtime(true);
+            if ($timelimit) {
+                $remainingtime = $stopat - $beforeindex;
+            }
+
+            // Show a message before each request, indicating what will be indexed.
+            $context = \context::instance_by_id($request->contextid);
+            $contextname = $context->get_context_name();
+            if ($request->searcharea) {
+                $contextname .= ' (search area: ' . $request->searcharea . ')';
+            }
+            $progress->output('Indexing requested context: ' . $contextname);
+
+            // Actually index the context.
+            $result = $this->index_context($context, $request->searcharea, $remainingtime,
+                    $progress, $request->partialarea, $request->partialtime);
+
+            // Work out shared part of message.
+            $endmessage = $contextname . ' (' . round(microtime(true) - $beforeindex, 1) . 's)';
+
+            // Update database table and continue/stop as appropriate.
+            if ($result->complete) {
+                // If we completed the request, remove it from the table.
+                $DB->delete_records('search_index_requests', ['id' => $request->id]);
+                $progress->output('Completed requested context: ' . $endmessage);
+            } else {
+                // If we didn't complete the request, store the partial details (how far it got).
+                $DB->update_record('search_index_requests', ['id' => $request->id,
+                        'partialarea' => $result->startfromarea,
+                        'partialtime' => $result->startfromtime]);
+                $progress->output('Ending requested context: ' . $endmessage);
+
+                // The time limit must have expired, so stop looping.
+                break;
+            }
+        }
+    }
+
 }
diff --git a/search/cli/indexer.php b/search/cli/indexer.php
index 8e204acb7bc..7129cfcc1a5 100644
--- a/search/cli/indexer.php
+++ b/search/cli/indexer.php
@@ -82,11 +82,26 @@ if (empty($options['reindex'])) {
         $limitunderline = preg_replace('~.~', '=', $limitinfo);
         echo "Running index of site$limitinfo\n";
         echo "=====================$limitunderline\n";
+        $timelimit = (int)$options['timelimit'];
     } else {
         echo "Running full index of site\n";
         echo "==========================\n";
+        $timelimit = 0;
     }
-    $globalsearch->index(false, $options['timelimit'], new text_progress_trace());
+    $before = time();
+    $globalsearch->index(false, $timelimit, new text_progress_trace());
+
+    // Do specific index requests with the remaining time.
+    if ($timelimit) {
+        $timelimit -= (time() - $before);
+        // Only do index requests if there is a reasonable amount of time left.
+        if ($timelimit > 1) {
+            $globalsearch->process_index_requests($timelimit, new text_progress_trace());
+        }
+    } else {
+        $globalsearch->process_index_requests(0, new text_progress_trace());
+    }
+
 } else {
     echo "Running full reindex of site\n";
     echo "============================\n";
diff --git a/search/tests/manager_test.php b/search/tests/manager_test.php
index 33fa8c53311..a655b940faa 100644
--- a/search/tests/manager_test.php
+++ b/search/tests/manager_test.php
@@ -738,4 +738,98 @@ class search_manager_testcase extends advanced_testcase {
         \core_search\manager::request_index($forum2ctx);
         $this->assertEquals(4, $DB->count_records('search_index_requests'));
     }
+
+    /**
+     * Tests the process_index_requests function.
+     */
+    public function test_process_index_requests() {
+        global $DB;
+
+        $this->resetAfterTest();
+
+        $search = testable_core_search::instance();
+
+        // When there are no index requests, nothing gets logged.
+        $progress = new progress_trace_buffer(new text_progress_trace(), false);
+        $search->process_index_requests(0.0, $progress);
+        $out = $progress->get_buffer();
+        $progress->reset_buffer();
+        $this->assertEquals('', $out);
+
+        // Set up the course with 3 forums.
+        $generator = $this->getDataGenerator();
+        $course = $generator->create_course(['fullname' => 'TCourse']);
+        $forum1 = $generator->create_module('forum', ['course' => $course->id, 'name' => 'TForum1']);
+        $forum2 = $generator->create_module('forum', ['course' => $course->id, 'name' => 'TForum2']);
+        $forum3 = $generator->create_module('forum', ['course' => $course->id, 'name' => 'TForum3']);
+
+        // Hack the forums so they have different creation times.
+        $now = time();
+        $DB->set_field('forum', 'timemodified', $now - 3, ['id' => $forum1->id]);
+        $DB->set_field('forum', 'timemodified', $now - 2, ['id' => $forum2->id]);
+        $DB->set_field('forum', 'timemodified', $now - 1, ['id' => $forum3->id]);
+        $forum2time = $now - 2;
+
+        // Make 2 index requests.
+        $search::request_index(context_course::instance($course->id), 'mod_label-activity');
+        $this->waitForSecond();
+        $search::request_index(context_module::instance($forum1->cmid));
+
+        // Run with no time limit.
+        $search->process_index_requests(0.0, $progress);
+        $out = $progress->get_buffer();
+        $progress->reset_buffer();
+
+        // Check that it's done both areas.
+        $this->assertContains(
+                'Indexing requested context: Course: TCourse (search area: mod_label-activity)',
+                $out);
+        $this->assertContains(
+                'Completed requested context: Course: TCourse (search area: mod_label-activity)',
+                $out);
+        $this->assertContains('Indexing requested context: Forum: TForum1', $out);
+        $this->assertContains('Completed requested context: Forum: TForum1', $out);
+
+        // Check the requests database table is now empty.
+        $this->assertEquals(0, $DB->count_records('search_index_requests'));
+
+        // Request indexing the course a couple of times.
+        $search::request_index(context_course::instance($course->id), 'mod_forum-activity');
+        $search::request_index(context_course::instance($course->id), 'mod_forum-post');
+
+        // Do the processing again with a time limit and indexing delay. The time limit is too
+        // small; because of the way the logic works, this means it will index 2 activities.
+        $search->get_engine()->set_add_delay(0.2);
+        $search->process_index_requests(0.1, $progress);
+        $out = $progress->get_buffer();
+        $progress->reset_buffer();
+
+        // Confirm the right wrapper information was logged.
+        $this->assertContains(
+                'Indexing requested context: Course: TCourse (search area: mod_forum-activity)',
+                $out);
+        $this->assertContains('Stopping indexing due to time limit', $out);
+        $this->assertContains(
+                'Ending requested context: Course: TCourse (search area: mod_forum-activity)',
+                $out);
+
+        // Check the database table has been updated with progress.
+        $records = array_values($DB->get_records('search_index_requests', null, 'searcharea'));
+        $this->assertEquals('mod_forum-activity', $records[0]->partialarea);
+        $this->assertEquals($forum2time, $records[0]->partialtime);
+
+        // Run again and confirm it now finishes.
+        $search->process_index_requests(0.1, $progress);
+        $out = $progress->get_buffer();
+        $progress->reset_buffer();
+        $this->assertContains(
+                'Completed requested context: Course: TCourse (search area: mod_forum-activity)',
+                $out);
+        $this->assertContains(
+                'Completed requested context: Course: TCourse (search area: mod_forum-post)',
+                $out);
+
+        // Confirm table is now empty.
+        $this->assertEquals(0, $DB->count_records('search_index_requests'));
+    }
 }