FIG. 1 is a perspective view of a toilet tissue holder with adjustable shelf in accordance with my design. FIG. 2 is a top plan view thereof; FIG. 3 is a front elevational view thereof; FIG. 4 is a side elevational view thereof as viewed from the left side of FIG. 1; FIG. 5 is a side elevational view thereof as viewed from the right side of FIG. 1; FIG. 6 is a rear elevational view thereof; and, FIG. 7 is a bottom plan view thereof.