here are the onliest citations in OED2; but then they're a long ways from coming back around to the Ls:

1857 A. ARMSTRONG N.W. Passage vii. 193 In the Esquimaux..we observed the lower lip perforated in the males, for the admission of labrets or lip ornaments. 1872 R. F. BURTON Zanzibar I. iv. 113 As a rule, the South American ‘Indians’ pierce for their labrets the lower lip. 1884 J. G. BOURKE Snake Dance of Moquis xxii. 243 They do not tattoo, do not use nose-rings or labrets.