  We present 65 optical spectra of the Type Ia supernova SN 2012fr, of which 33
were obtained before maximum light. At early times SN 2012fr shows clear
evidence of a high-velocity feature (HVF) in the Si II 6355 line which can be
cleanly decoupled from the lower velocity "photospheric" component. This Si II
6355 HVF fades by phase -5; subsequently, the photospheric component exhibits a
very narrow velocity width and remains at a nearly constant velocity of
v~12,000 km/s until at least 5 weeks after maximum brightness. The Ca II
infrared (IR) triplet exhibits similar evidence for both a photospheric
component at v~12,000 km/s with narrow line width and long velocity plateau, as
well as a high-velocity component beginning at v~31,000 km/s two weeks before
maximum. SN 2012fr resides on the border between the "shallow silicon" and
"core-normal" subclasses in the Branch et al. (2009) classification scheme, and
on the border between normal and "high-velocity" SNe Ia in the Wang et al.
(2009a) system. Though it is a clear member of the "low velocity gradient"
(LVG; Benetii et al., 2005) group of SNe Ia and exhibits a very slow
light-curve decline, it shows key dissimilarities with the overluminous SN
1991T or SN 1999aa subclasses of SNe Ia. SN 2012fr represents a well-observed
SN Ia at the luminous end of the normal SN Ia distribution, and a key
transitional event between nominal spectroscopic subclasses of SNe Ia.
