(defun test-loop ()
  (let ((orig (list 1 2 3 'x 4 5 6 7 'x 8 9))
        (delimiter 'x))
    (loop for list = orig then tail
          for (head tail)
            = (loop for sublist on list
                    until (eql (car sublist) delimiter)
                    collect (car sublist) into first-part
                    finally (return (list first-part (cdr sublist))))
          until (endp list)
          collect head)))