function counter(object){
    var limit = $(object).attr('maxlength');

    if($(object).next(".counter").val()==undefined){
        $(object).after("<span class='counter'></span>/"+limit);
    }
    $(object).textlimit("span.counter",100);
}

<input type="text" onkeypress="counter(this);" id="partnerinfoname" maxlength="100" />