I was searching help on this too. It took me a while, but here is what I did that worked really well.
<Target Name="AfterBuild">
<ItemGroup>
<ANTLR Include="..\Data\antlrcs\**\*.*" />
</ItemGroup>
<Copy SourceFiles="@(ANTLR)" DestinationFolder="$(TargetDir)\%(RecursiveDir)" SkipUnchangedFiles="true" />
</Target>
This recursively copied the contents of the folder named antlrcs
to the $(TargetDir)
.