diff -u b/core/modules/search/search.module b/core/modules/search/search.module
--- b/core/modules/search/search.module
+++ b/core/modules/search/search.module
@@ -855,40 +855,61 @@
   $words[] = array('', strlen($text));
   $num_words = count($words);
 
-  // Find the smallest segment of complete words in $text that we can simplify
-  // to match $simplified_key.
-  $start_position = 0;
-  $word_end = 0;
-  for ($word_index = 0; $word_index < $num_words; $word_index++) {
-    // See if we can move the starting position out from our previously-saved
-    // best position to here and still have a match.
-    $trial_position = $words[$word_index][1];
-    if ($trial_position < strlen($text)) {
-      $candidate = substr($text, $trial_position);
-      $test_text = trim(search_simplify($candidate, $langcode));
-      if (strpos($test_text, $simplified_key) !== FALSE) {
-        $start_position = $trial_position;
-        $word_end = $trial_position + strlen($words[$word_index][0]);
-        continue;
-      }
+  // Using a binary search, find the earliest possible ending position in
+  // $text where it will still match the keyword after applying
+  // search_simplify().
+  $start_index = 0;
+  $start_pos = $words[$start_index][1];
+  $min_end_index = 1;
+  $max_end_index = count($words) - 1;
+  while ($max_end_index > $min_end_index) {
+    // Check the index half way between min and max. See if we ended there,
+    // if we would still have a match.
+    $proposed_end_index = floor(($max_end_index + $min_end_index) * 0.5);
+    $proposed_end_pos = $words[$proposed_end_index][1];
+    // Since the split was done with preg_split(), the positions are byte counts
+    // not character counts, so use substr() not Unicode::substr() here.
+    $trial_text = trim(search_simplify(substr($text, $start_pos, $proposed_end_pos - $start_pos), $langcode));
+    if (strpos($trial_text, $simplified_key) !== FALSE) {
+      // The proposed endpoint is fine, text still matches.
+      $max_end_index = $proposed_end_index;
     }
-
-    // See if we can end at our currently-saved word-ending position and still
-    // match, in which case this is the minimal matching string.
-    if ($word_end > $start_position) {
-      $candidate = substr($text, $start_position, $word_end - $start_position);
-      $test_text = trim(search_simplify($candidate, $langcode));
-      if (strpos($test_text, $simplified_key) !== FALSE) {
-        return $candidate;
-      }
+    else {
+      // The proposed endpoint is too early, so the earliest possible
+      // OK ending would be the next word.
+      $min_end_index = $proposed_end_index + 1;
     }
+  }
 
-    // Save the end position of this word for the next time through this loop.
-    $word_end = $trial_position + strlen($words[$word_index][0]);
+  // Now do the same for the starting position: using a binary search, find the
+  // latest possible starting position in $text where it will still match the
+  // keyword after applying search_simplify().
+  $end_index = $min_end_index;
+  $end_pos = $words[$end_index][1];
+  $min_start_index = 0;
+  $max_start_index = $end_index - 1;
+  while ($max_start_index > $min_start_index) {
+    // Check the index half way between min and max. See if we started there,
+    // if we would still have a match.
+    $proposed_start_index = ceil(($max_start_index + $min_start_index) * 0.5);
+    $proposed_start_pos = $words[$proposed_start_index][1];
+    // Since the split was done with preg_split(), the positions are byte counts
+    // not character counts, so use substr() not Unicode::substr() here.
+    $trial_text = trim(search_simplify(substr($text, $proposed_start_pos, $end_pos - $proposed_start_pos), $langcode));
+    if (strpos($trial_text, $simplified_key) !== FALSE) {
+      // The proposed start point is fine, text still matches.
+      $min_start_index = $proposed_start_index;
+    }
+    else {
+      // The proposed start point is too late, so the latest possible
+      // OK starting point would be the previous word.
+      $max_start_index = $proposed_start_index - 1;
+    }
   }
+  $start_index = $max_start_index;
 
-  // If we get here, we couldn't find a match.
-  return NULL;
+  // Return the matching text.
+  return trim(substr($text, $words[$start_index][1], $words[$end_index][1] - $words[$start_index][1]));
 }
 
 /**