Just in time for what would have been the 85th birthday of Miles Davis, LIFE.com has posted never-before-seen photos of the jazz pioneer.

The circumstances behind the images:

When LIFE photographer Robert W. Kelley snapped a few rolls of film at an intimate jazz gig on May 14, 1958, neither he nor the magazine's editors could have known the importance of what he had witnessed. Perhaps that's why Kelley provided only scant notes -- just the date and the city and the subject's name, "Miles Davis" -- scrawled on the small archival file of the images; perhaps that's why the bulk of them, which capture trumpeter Davis, then just 31 years old, leading his band in an unnamed New York venue, never made it to print.

Three of the shots are below; for more, visit LIFE.com.