FOR REAL: Kylie started out in Australia, a Western Aboriginal word for a boomerang-like throwing stick used as a hunting weapon.

The first appearance if Kylie in English occurs in G.F. Moore's Diary of Ten Years Eventful Life of an Early Settler in Western Australia (published in 1884, but referring to an 1835 diary entry):

I am sorry that nasty word 'boomerang' has been suffered to supercede the proper name. Boomerang is a corruption used at Sydney by the white people, but not the native word, which is tur-ra-ma; but 'kiley' is the name here.

Its popularity as a girls' name in the late 1960s and early 1970s in Australia was definitely influenced by the fact that at the time, similar names like Kelly and Kyle were also popular. Singer Kylie Minogue brought international fame to the name where it is now popular in other English speaking countries.

Kiley, though now it is used as an alternate spelling of Kylie, is a separate name; an anglicization of the Irish surname Ó Cadhla (also anglicized Kiely), which stems from a personal name that means "graceful."