#(define longup
   (grob-transformer 'stencil (lambda (grob orig)
     (ly:stencil-combine-at-edge
     (ly:stencil-aligned-to
       (grob-interpret-markup grob
                              (markup #:override '(font-encoding . latin1) #:italic "long"))
       X 0)
     Y DOWN orig 0))))

{
   r2 r4 r8
   r8-\tweak stencil #longup -\fermata
   r2 r4 r8
   r8-\tweak stencil #longup -\fermata
}