\version "2.15.22"

 extendLV = #(define-music-function (parser location further) (number?) 
#{
   \once \override LaissezVibrerTie  #'X-extent = #'(0 . 0)
   \once \override LaissezVibrerTie  #'details #'note-head-gap = #(/ further -2)
   \once \override LaissezVibrerTie  #'extra-offset = #(cons (/ further 2) 0)
#})

   \relative c' {
	\clef treble
	\key c \major
	\time 4/4

        \extendLV #1.2 <c e g>2\laissezVibrer <b d g>2

	}