Leylands are fast growing..everyones answer to the lack of privacy that comes from carving up the land into little 1/4-1/2 acre kingdoms.
Sometimes, if weather is cooperative and you have the right amount of rain, you can snip off the effected tips(providing you have only 3-4 per tree) and expect the tree to survive.
The drought, combined with the widespread disease spores..the leylands planted side by side EVERYWHERE haven't a chance.
Dig them out before they become a dead, fire-hazard mess and don't replant. The soil now, at least in widespread areas of the Carolinas, is almost bone dry at the 12" depth. Water in the hole will just migrate out further unless you lay down drip irrigation.
Sorry. We have to get the soil moisture level back closer to normal before we go investing in replanting these privacy 'hedges'.