diff --git a/build.gradle b/build.gradle
index ebe244a..23d3e0c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1671,7 +1671,11 @@
         enableAssertions = false
     }
     // TODO(b/124091860): Increase the max heap size to avoid OOM when running tests.
-    maxHeapSize = "4g"
+    if (project.hasProperty('test_xmx')) {
+      maxHeapSize = project.property('test_xmx')
+    } else {
+      maxHeapSize = "4G"
+    }
 }
 
 task buildPreNJdwpTestsJar(type: Jar) {
diff --git a/tools/internal_test.py b/tools/internal_test.py
index cb6e882..a0cc52b 100755
--- a/tools/internal_test.py
+++ b/tools/internal_test.py
@@ -58,7 +58,7 @@
 TEST_COMMANDS = [
     # Run test.py internal testing.
     ['tools/test.py', '--only_internal', '--slow_tests',
-     '--java_max_memory_size=12G'],
+     '--java_max_memory_size=8G'],
     # Ensure that all internal apps compile.
     ['tools/run_on_app.py', '--ignore-java-version','--run-all', '--out=out']
 ]
diff --git a/tools/test.py b/tools/test.py
index 6e7bfd9..2d45d1c 100755
--- a/tools/test.py
+++ b/tools/test.py
@@ -103,7 +103,8 @@
   result.add_option('--java-home', '--java_home',
       help='Use a custom java version to run tests.')
   result.add_option('--java-max-memory-size', '--java_max_memory_size',
-      help='Use a custom max memory size for the gradle java instance, eg, 4g')
+      help='Set memory for running tests, default 4G',
+      default='4G')
   result.add_option('--shard-count', '--shard_count',
       help='We are running this many shards.')
   result.add_option('--shard-number', '--shard_number',
@@ -193,7 +194,7 @@
   if options.java_home:
     gradle_args.append('-Dorg.gradle.java.home=' + options.java_home)
   if options.java_max_memory_size:
-    gradle_args.append('-Dorg.gradle.jvmargs=-Xmx' + options.java_max_memory_size)
+    gradle_args.append('-Ptest_xmx=' + options.java_max_memory_size)
   if options.generate_golden_files_to:
     gradle_args.append('-Pgenerate_golden_files_to=' + options.generate_golden_files_to)
     if not os.path.exists(options.generate_golden_files_to):