ILmerge.exe download link from Microsoft.

info: http://research.microsoft.com/en-us/people/mbarnett/ILMerge.aspx

For example, the following command could be issued to combine one primary assembly and two secondary assemblies into a single merged DLL file:

ilmerge /out:Merged.dll Primary.dll Secondary1.dll Secondary2.dll

using wildcard:
ilmerge /wildcards /out:Merged.dll Primary.dll Secondary*.dll

log:
ilmerge /log:log.txt /out:Merged.dll Primary.dll Secondary1.dll Secondary2.dll