Rotting roof truss repair help

Hi, not sure what to do here. The roof rafter is up against the chimney breast and as you can see water has rotted the rafter and supporting timber. The chimney will have lead flashing fitted to stop the leak. I was hoping to perhaps treat the rotted timbers and perhaps reinforce the rafter and support but advice is needed here what treatment is best and the best way to repair the damage. Thank you Paul M Attachment 42761 (http://www.doityourself.com/forum/attachments/roofing-gutters-all-waterproofing-anywhere/42761-rotting-roof-truss-repair-help-image.jpg)