Holly tree leaves
Complete browning and dieback like this suggest a root or trunk problem. When was this tree planted? If it was planted within the last two years, it may not have established well if it was planted incorrectly. It looks like it may have been planted too deeply. Also, it looks like it is located in front of a downspout. If the soil has remained saturated for a long period of time (last year we had an excessive amount of rainfall), this could have resulted in root rot -- which will lead to an overall decline. Mulch that is too thick also can lead to problems. Mulch should be no deeper than 2-3" and avoid putting it again the trunk of a tree.
Unfortunately, this plant looks like it is finished. Consider replacement with another shrub that would be suitable for your soil conditions. You may need to re-direct the downspout. Start by testing your soil to check your pH, organic matter, and nutrient content. Here is some information for you on shrub planting and soil testing.