  Two planetary mass objects in the far outer Solar System --- collectively
referred to here as Planet X --- have recently been hypothesized to explain the
orbital distribution of distant Kuiper Belt Objects. Neither planet is thought
to be exceptionally faint, but the sky locations of these putative planets are
poorly constrained. Therefore, a wide area survey is needed to detect these
possible planets. The Large Synoptic Survey Telescope (LSST) will carry out an
unbiased, large area (around 18,000 deg$^2$), deep (limiting magnitude of
individual frames of 24.5) survey (the "wide-fast-deep" survey) of the southern
sky beginning in 2022, and is therefore an important tool to search for these
hypothesized planets. Here we explore the effectiveness of LSST as a search
platform for these possible planets. Assuming the current baseline cadence
(which includes the wide-fast-deep survey plus additional coverage) we estimate
that LSST will confidently detect or rule out the existence of Planet X in 61\%
of the entire sky. At orbital distances up to $\sim$75 au, Planet X could
simply be found in the normal nightly moving object processing; at larger
distances, it will require custom data processing. We also discuss the
implications of a non-detection of Planet X in LSST data.
