At the moment, I just assume that there is no public library that does this for us, so I'm going to use the Google code to add polylines and polygons to my map after parsing the data in my KML file. This answer will be updated if the library is found.
Create polylines and polygons:
PolylineOptions rectOptions = new PolylineOptions()
.add(new LatLng(37.35, -122.0))
.add(new LatLng(37.45, -122.0))
.add(new LatLng(37.45, -122.2))
.add(new LatLng(37.35, -122.2))
.add(new LatLng(37.35, -122.0));
rectOptions.color(Color.RED);
Polyline polyline = myMap.addPolyline(rectOptions);
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