Invoking reflected case class constructor in Scala

I can get the default constructor of a case class via static reflection thusly:

val symbol = currentMirror.classSymbol(myObj.getClass).typeSignature.typeSymbol.asClass
val ctor = symbol.primaryConstructor

From here I can do nifty things like introspect details of its fields, etc. But how can I now invoke the constructor method? I could dig into myObj's class, but if it has multiple constructors, is there a straightforward way to match the right constructor to the one I got from primaryConstructor?