  Using the conditional luminosity function (CLF) -- the luminosity
distribution of galaxies in a dark matter halo -- as a way to model galaxy
statistics, we study how z=4 Lyman Break Galaxies (LBGs) are distributed in
dark matter halos. For this purpose, we measure luminosity-dependent clustering
of LBGs in the Subaru/XMM-Newton Deep Field by separating a sample of 16,920
galaxies to three magnitude bins in i'-band between 24.5 and 27.5. Our models
fits to data show a possible trend for more luminous galaxies to appear as
satellites in more massive halos. The satellite fraction of galaxies at z=4 in
these magnitude bins is 0.13 to 0.3, 0.09 to 0.22, and 0.03 to 0.14,
respectively, where the 1 sigma ranges account for differences coming from two
different estimates of the z=4 LF from the literature. To jointly explain the
LF and the large-scale linear bias factor of z=4 LBGs as a function of rest-UV
luminosity requires central galaxies to be brighter in UV at z =4 than
present-day galaxies in same dark matter mass halos. Moreover, UV luminosity of
central galaxies in halos with total mass greater than roughly 10^{12} M_sun
must decrease from z=4 to today by an amount more than the luminosity change
for galaxies in halos below this mass. This mass-dependent luminosity evolution
is preferred at more than 3 sigma confidence level compared to a
pure-luminosity evolution scenario where all galaxies decrease in luminosity by
the same amount from z=4 to today. The scenario preferred by the data is
consistent with the ``down-sizing'' picture of galaxy evolution.
