If you know the pattern you are using:
var date = Globalize.parseDate("07/17/2013 11:55 pm", "MM/dd/yyyy hh:mm tt");
If you don't know the pattern:
var date = Globalize.parseDate("07/17/2013 11:55 pm", Globalize.culture().calendar.patterns.d + " " + Globalize.culture().calendar.patterns.t)
The line above is assuming current culture, if you need it for other culture or if you haven't established the local culture by calling Globalize.culture("") then just specify the culture on culture().
I just ran on this scenario a few minutes ago, and found this solution, the latest it is messy, I hope there is a cleaner way to do this.
Note: This is only applicable to the deprecated Globalize 0.x.
Note 2: Passing a hardcoded pattern is NOT an i18n recommendation.