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We report updates to an ongoing lattice-QCD calculation of the form factorsfor the semileptonic decays $B \to \pi \ell \nu$, $B_s \to K \ell \nu$, $B \to\pi \ell^+ \ell^-$, and $B \to K \ell^+ \ell^-$. The tree-level decays $B_{(s)}\to \pi (K) \ell \nu$ enable precise determinations of the CKM matrix element$|V_{ub}|$, while the flavor-changing neutral-current interactions $B \to \pi(K) \ell^+ \ell^-$ are sensitive to contributions from new physics. This workuses MILC's (2+1+1)-flavor HISQ ensembles at approximate lattice spacingsbetween $0.057$ and $0.15$ fm, with physical sea-quark masses on four out ofthe seven ensembles. The valence sector is comprised of a clover $b$ quark (inthe Fermilab interpretation) and HISQ light and $s$ quarks. We presentpreliminary results for the form factors $f_0$, $f_+$, and $f_T$, includingstudies of systematic errors.

$B$-meson semileptonic form factors on (2+1+1)-flavor HISQ ensembles