--- a/mx.graal/mx_graal.py	Tue Jul 21 02:20:47 2015 +0200
+++ b/mx.graal/mx_graal.py	Tue Jul 21 15:16:00 2015 +0200
@@ -32,7 +32,9 @@
 
 import mx
 import mx_jvmci
-from mx_jvmci import JDKDeployedDist, buildvms, vm, VM, Task, parseVmArgs, get_vm, unittest, ctw, isVMSupported
+from mx_jvmci import JDKDeployedDist, buildvms, vm, VM, Task, parseVmArgs, get_vm, ctw, isVMSupported
+import mx_unittest
+from mx_unittest import unittest
 
 _suite = mx.suite('graal')
 
@@ -72,6 +74,17 @@
 mx_jvmci.jacocoIncludes += ['com.oracle.graal.*']
 mx_jvmci.jacocoExcludedAnnotations += ['@Snippet', '@ClassSubstitution']
 
+def _unittest_config_participant(config):
+    vmArgs, mainClass, mainClassArgs = config
+    # Unconditionally prepend truffle.jar to the boot class path.
+    # This used to be done by the VM itself but was removed to
+    # separate the VM from Truffle.
+    truffle_jar = mx.distribution('truffle:TRUFFLE').path
+    vmArgs = ['-Xbootclasspath/p:' + truffle_jar] + vmArgs
+    return (vmArgs, mainClass, mainClassArgs)
+
+mx_unittest.add_config_participant(_unittest_config_participant)
+
 def _run_benchmark(args, availableBenchmarks, runBenchmark):
 
     vmOpts, benchmarksAndOptions = mx.extract_VM_args(args, useDoubleDash=availableBenchmarks is None)