Since JDK-8044022 was completed `java -x` output should not contain '-Xincgc' option.
Promoted 9b49:
./java -version
java version "1.9.0-ea"
Java(TM) SE Runtime Environment (build 1.9.0-ea-b49)
Java HotSpot(TM) Server VM (build 1.9.0-ea-b49, mixed mode)
./java -X
-Xmixed mixed mode execution (default)
-Xint interpreted mode execution only
-Xbootclasspath:<directories and zip/jar files separated by :>
set search path for bootstrap classes and resources
-Xbootclasspath/a:<directories and zip/jar files separated by :>
append to end of bootstrap class path
-Xbootclasspath/p:<directories and zip/jar files separated by :>
prepend in front of bootstrap class path
-Xdiag show additional diagnostic messages
-Xnoclassgc disable class garbage collection
-Xincgc enable incremental garbage collection
...