Wpf: tabitem header to match header.content size

I have a tab control, and when there are too many, I get the headings of the title elements on several lines. So it will be like

[TabItemAA1] [TabItemAA2]
[        TabItem3       ]
[TabItem4AAAAAAAAAAAAAAA]

I don't mind stacking them, but when that happens, the TabItem3 header is stretched to fit the width of the tab control. How can I prevent this or make the contents of a tab element that TextBlock is suitable for extended widths?

thank