My program HARMONY can do this, as noted above (On a Windows PC only though).

And it is free for the first month (Fully functional).
It can also add (suggest) chords for a melody.

For guitar:

The score options include Guitar staff, with all notes shown in the treble cleff.

I have almost finished the full Guitar Tablature option, which will let you define your own tunings, and can generate chords to fit the tuning. (The guitar tab in version 3.4.1 has an error, so don't use it! It loses accidentals when they are in the key signature).

Download from my site Green Hedges