Best WPF text control for dynamic styling

Question

I am trying to localize a WPF application, but am running into a problem with formatting. Say you have the following:

<Run>Text</Run>
<Bold>Emphasis</Bold>
<Run>Rest</Run>

I need a way to dynamically create this. Is there a good control for this?

Additional Reasoning

Different languages could have emphasis in different places and result in bold being first, or there being 4 total inlines, thus why I would like to have one localized string like this:

Text <Bold>Emphasis</Bold> Rest