"Bayliss and Roberts will arrive on August 11 with Paul coming in two days later," Sri Lanka Cricket secretary Kangadaran Mathivanan told AFP.
Bayliss is a former New South Wales coach while Fabrice was serving on the staff of English county side Kent before being picked by Sri Lanka.
The Sri Lankan squad, led by Mahela Jayawardene, will train for the championships from August 20 before leaving for South Africa on September 5, Mathivanan said.
The 12-nation world championships will be played in Johannesburg, Cape Town and Durban from September 11-24. Sri Lanka are drawn with New Zealand and Kenya in group C of the premliminary league, with the top two advancing to the Super Eights round.