--- a/mx/mx_graal.py	Tue Feb 11 14:26:48 2014 -0800
+++ b/mx/mx_graal.py	Tue Feb 11 15:07:50 2014 -0800
@@ -1071,21 +1071,23 @@
         mx.pylint([])
         tasks.append(t.stop())
 
-        t = Task('Clean')
-        cleanArgs = []
-        if not args.cleanNative:
-            cleanArgs.append('--no-native')
-        if not args.cleanJava:
-            cleanArgs.append('--no-java')
-        clean(cleanArgs)
-        tasks.append(t.stop())
+        def _clean(name='Clean'):
+            t = Task(name)
+            cleanArgs = []
+            if not args.cleanNative:
+                cleanArgs.append('--no-native')
+            if not args.cleanJava:
+                cleanArgs.append('--no-java')
+            clean(cleanArgs)
+            tasks.append(t.stop())
+        _clean()
 
         t = Task('IDEConfigCheck')
         mx.ideclean([])
         mx.ideinit([])
         tasks.append(t.stop())
 
-        eclipse_exe = os.environ.get('ECLIPSE_EXE')
+        eclipse_exe = mx.get_env('ECLIPSE_EXE')
         if eclipse_exe is not None:
             t = Task('CodeFormatCheck')
             if mx.eclipseformat(['-e', eclipse_exe]) != 0:
@@ -1098,8 +1100,15 @@
             t.abort('Rerun "mx canonicalizeprojects" and check-in the modified mx/projects files.')
         tasks.append(t.stop())
 
-        t = Task('BuildJava')
-        build(['--no-native', '--jdt-warning-as-error'])
+        if mx.get_env('JDT'):
+            t = Task('BuildJavaWithEcj')
+            build(['--no-native', '--jdt-warning-as-error'])
+            tasks.append(t.stop())
+
+            _clean('CleanAfterEcjBuild')
+
+        t = Task('BuildJavaWithJavac')
+        build(['--no-native', '--force-javac'])
         tasks.append(t.stop())
 
         t = Task('Checkstyle')

--- a/mxtool/mx.py	Tue Feb 11 14:26:48 2014 -0800
+++ b/mxtool/mx.py	Tue Feb 11 15:07:50 2014 -0800
@@ -1557,6 +1557,7 @@
     parser.add_argument('--only', action='store', help='comma separated projects to build, without checking their dependencies (omit to build all projects)')
     parser.add_argument('--no-java', action='store_false', dest='java', help='do not build Java projects')
     parser.add_argument('--no-native', action='store_false', dest='native', help='do not build native projects')
+    parser.add_argument('--force-javac', action='store_true', dest='javac', help='use javac despite ecj.jar is found or not')
     parser.add_argument('--jdt', help='path to ecj.jar, the Eclipse batch compiler (default: ' + defaultEcjPath + ')', default=defaultEcjPath, metavar='<path>')
     parser.add_argument('--jdt-warning-as-error', action='store_true', help='convert all Eclipse batch compiler warnings to errors')
 
@@ -1566,7 +1567,7 @@
     args = parser.parse_args(args)
 
     jdtJar = None
-    if args.jdt is not None:
+    if not args.javac and args.jdt is not None:
         if not args.jdt.endswith('.jar'):
             abort('Path for Eclipse batch compiler does not look like a jar file: ' + args.jdt)
         jdtJar = args.jdt