We introduce a novel abundance matching technique that produces a more accurate estimate of the pre-infall halo mass, $M_{200}$, for satellite galaxies. To achieve this, we abundance match with the mean star formation rate, averaged over the time when a galaxy was forming stars, $langle {rm SFR}rangle$, instead of the stellar mass, $M_*$. Using data from the Sloan Digital Sky Survey, the GAMA survey and the Bolshoi simulation, we obtain a statistical $langle {rm SFR}rangle-{rm M}_{200}$ relation in $Lambda{rm CDM}$. We then compare the pre-infall halo mass, $M^{rm abund}_{200}$, derived from this relation with the pre-infall dynamical mass, $M^{rm dyn}_{200}$, for 21 nearby dSph and dIrr galaxies, finding a good agreement between the two. As a first application, we use our new $langle {rm SFR}rangle-{rm M}_{200}$ relation to empirically measure the cumulative mass function of a volume-complete sample of bright Milky Way satellites within 280 kpc of the Galactic centre. Comparing this with a suite of cosmological zoom simulations of Milky Way-mass halos that account for subhalo depletion by the Milky Way disc, we find no missing satellites problem above $M_{200} sim 10^9,{rm M}_odot$ in the Milky Way. We discuss how this empirical method can be applied to a larger sample of nearby spiral galaxies.
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