diff --git a/simple-comment-markup.el b/simple-comment-markup.el
index eccf27b..3b2dbc0 100644
--- a/simple-comment-markup.el
+++ b/simple-comment-markup.el
@@ -97,47 +97,96 @@ This must not include any capturing groups."
      (lambda (a b)
        (string-lessp (plist-get b :start) (plist-get a :start))))))
 
-(defun simple-comment-markup--construct-font-lock (&optional set)
+(defvar-local simple-comment-markup--rx-patterns nil)
+
+(defun simple-comment-markup--construct-rx-patterns (&optional set)
   "Return a font-lock construct for markup patterns from SET."
   (let ((patterns (simple-comment-markup--get-patterns set)))
-    (list
-     (apply #'append
-            (list (rx line-start (* blank) (literal comment-start)))
-            (mapcar
-             (lambda (pattern)
-               (let* ((confounding-start-characters
-                       (delq nil
-                             (mapcar
-                              (lambda (pat)
-                                (and (> (length (plist-get pat :start))
-                                        (length (plist-get pattern :start)))
-                                     (string= (plist-get pattern :start)
-                                              (substring
-                                               (plist-get pat :start)
-                                               0 (length (plist-get pattern :start))))
-                                     (aref (plist-get pat :start)
-                                           (length (plist-get pattern :start)))))
-                              patterns)))
-                      (body-rx
-                       (or (plist-get pattern :body)
-                           (rx-to-string
-                            `(seq (not (any space ,@confounding-start-characters))
-                              (optional
-                               (*? not-newline)
-                               (not space)))))))
-                 `((,(rx (regexp simple-comment-markup-pre-rx)
-                         (group (literal (plist-get pattern :start)))
-                         (group (regexp body-rx))
-                         (group (literal (plist-get pattern :end)))
-                         (regexp simple-comment-markup-post-rx))
-                    (beginning-of-line)
-                    nil
-                    (1 'simple-comment-markup-face t)
-                    (2 '(face ,(plist-get pattern :face)) prepend)
-                    (3 'simple-comment-markup-face t)))))
-             patterns)))))
+    (mapcar
+     (lambda (pattern)
+       (let* ((confounding-start-characters
+               (delq nil
+                     (mapcar
+                      (lambda (pat)
+                        (and (> (length (plist-get pat :start))
+                                (length (plist-get pattern :start)))
+                             (string= (plist-get pattern :start)
+                                      (substring
+                                       (plist-get pat :start)
+                                       0 (length (plist-get pattern :start))))
+                             (aref (plist-get pat :start)
+                                   (length (plist-get pattern :start)))))
+                      patterns)))
+              (body-rx
+               (or (plist-get pattern :body)
+                   (rx-to-string
+                    `(seq (not (any space ,@confounding-start-characters))
+                      (optional
+                       (*? not-newline)
+                       (not space)))))))
+         (cons
+          (rx (regexp simple-comment-markup-pre-rx)
+              (group (literal (plist-get pattern :start)))
+              (group (regexp body-rx))
+              (group (literal (plist-get pattern :end)))
+              (regexp simple-comment-markup-post-rx))
+          (plist-get pattern :face))))
+     patterns)))
 
-(defvar-local simple-comment-markup--font-lock-keywords nil)
+(defun simple-comment-markup--fontify (&optional limit)
+  "Apply comment markup up to LIMIT, based on `simple-comment-markup--rx-patterns'."
+  (let ((syntax-ppss-table (syntax-table))
+        (markup-start nil)
+        (markup-end 0)
+        (multiline nil))
+    (while (re-search-forward (rx (syntax comment-start)) limit t)
+      (when (nth 8 (syntax-ppss)) ; Inside comment or string
+        (unless markup-start
+          (setq markup-start (point)))
+        (let ((continue t))
+          (while continue
+            (setq markup-end
+                  (max markup-end
+                       (simple-comment-markup--fontify-line limit)))
+            (if (eobp)
+                (setq continue nil)
+              (forward-line 1)
+              (setq continue (nth 8 (syntax-ppss)))
+              (when (and continue (not multiline))
+                (setq multiline
+                      (save-excursion
+                        (not
+                         (re-search-forward
+                          (rx point (syntax comment-start)) nil t))))))))))
+    (when multiline
+      (put-text-property markup-start markup-end 'font-lock-multiline t))
+    (set-match-data (and markup-start (list markup-start markup-end)))))
+
+(defun simple-comment-markup--fontify-line (&optional limit)
+  "Apply comment markup up to LIMIT or the end of the current line."
+  (let ((start (point))
+        (max-end 0)
+        (line-limit (min (or limit (point-max)) (line-end-position)))
+        continue)
+    (dolist (pattern simple-comment-markup--rx-patterns)
+      (goto-char start)
+      (setq continue t)
+      (while continue
+        (setq continue nil)
+        (when (re-search-forward (car pattern) line-limit t)
+          (setq continue (nth 8 (syntax-ppss)))
+          (when continue
+            (add-face-text-property
+             (match-beginning 1) (match-end 1) 'simple-comment-markup-face)
+            (add-face-text-property
+             (match-beginning 2) (match-end 2) (cdr pattern))
+            (add-face-text-property
+             (match-beginning 3) (match-end 3) 'simple-comment-markup-face)
+            (setq max-end (max max-end (match-end 0)))))))
+    max-end))
+
+(defvar simple-comment-markup--font-lock-keywords
+  '((simple-comment-markup--fontify)))
 
 ;;;###autoload
 (define-minor-mode simple-comment-markup-mode
@@ -146,8 +195,8 @@ This must not include any capturing groups."
   :group 'simple-comment-markup
   (cond
    (simple-comment-markup-mode
-    (setq simple-comment-markup--font-lock-keywords
-          (simple-comment-markup--construct-font-lock))
+    (setq simple-comment-markup--rx-patterns
+          (simple-comment-markup--construct-rx-patterns))
     (font-lock-add-keywords nil simple-comment-markup--font-lock-keywords 'append))
    (t (font-lock-remove-keywords nil simple-comment-markup--font-lock-keywords)))
   (save-restriction