diff --git a/changelog.md b/changelog.md
index 74d3c5cafd..a63c9d7504 100644
--- a/changelog.md
+++ b/changelog.md
@@ -4,7 +4,10 @@
 
 ### Version 5.0.3
 
-* `webserver`: The `corda-webserver` component has been renamed to `corda-testserver.`
+* `quasar-utils`: Add `excludeClassLoaders` option to the `quasar` extension. This option requires Quasar 0.7.12_r3 and above, excluding 0.8.0.
+
+* `cordformation`: The `corda-webserver` component has been renamed to `corda-testserver.`
+
 * `jar-filter`: Support for byte-code compiled by Kotlin >= 1.3.40 (See [KT-30289](https://youtrack.jetbrains.com/issue/KT-30289)).
 
 ### Version 5.0.2
diff --git a/quasar-utils/src/main/groovy/net/corda/plugins/QuasarExtension.groovy b/quasar-utils/src/main/groovy/net/corda/plugins/QuasarExtension.groovy
index e6a27b0a59..e83232409e 100644
--- a/quasar-utils/src/main/groovy/net/corda/plugins/QuasarExtension.groovy
+++ b/quasar-utils/src/main/groovy/net/corda/plugins/QuasarExtension.groovy
@@ -35,6 +35,7 @@ class QuasarExtension {
      * - debug
      * - verbose
      * - globs of packages not to instrument.
+     * - globs of classloaders not to instrument.
      */
     final Property<Boolean> debug
 
@@ -42,6 +43,8 @@ class QuasarExtension {
 
     final ListProperty<String> excludePackages
 
+    final ListProperty<String> excludeClassLoaders
+
     @PackageScope
     final Provider<String> options
 
@@ -51,7 +54,8 @@ class QuasarExtension {
         String defaultGroup,
         String defaultVersion,
         String defaultClassifier,
-        Iterable<? extends String> initialExclusions
+        Iterable<? extends String> initialPackageExclusions,
+        Iterable<? extends String> initialClassLoaderExclusions
     ) {
         group = objects.property(String).convention(defaultGroup)
         version = objects.property(String).convention(defaultVersion)
@@ -67,21 +71,28 @@ class QuasarExtension {
         debug = objects.property(Boolean).convention(false)
         verbose = objects.property(Boolean).convention(false)
         excludePackages = objects.listProperty(String)
-        excludePackages.set(initialExclusions)
-        options = excludePackages.flatMap { excludes ->
-            debug.flatMap { isDebug ->
-                verbose.map { isVerbose ->
-                    def builder = new StringBuilder('=')
-                    if (isDebug) {
-                        builder.append('d')
-                    }
-                    if (isVerbose) {
-                        builder.append('v')
-                    }
-                    if (!excludes.isEmpty()) {
-                        builder.append('x(').append(excludes.join(';')).append(')')
+        excludePackages.set(initialPackageExclusions)
+        excludeClassLoaders = objects.listProperty(String)
+        excludeClassLoaders.set(initialClassLoaderExclusions)
+        options = excludePackages.flatMap { packages ->
+            excludeClassLoaders.flatMap { classLoaders ->
+                debug.flatMap { isDebug ->
+                    verbose.map { isVerbose ->
+                        def builder = new StringBuilder('=')
+                        if (isDebug) {
+                            builder.append('d')
+                        }
+                        if (isVerbose) {
+                            builder.append('v')
+                        }
+                        if (!packages.isEmpty()) {
+                            builder.append('x(').append(packages.join(';')).append(')')
+                        }
+                        if (!classLoaders.isEmpty()) {
+                            builder.append('l(').append(classLoaders.join(';')).append(')')
+                        }
+                        builder.length() == 1 ? '' : builder.toString()
                     }
-                    builder.length() == 1 ? '' : builder.toString()
                 }
             }
         }
diff --git a/quasar-utils/src/main/groovy/net/corda/plugins/QuasarPlugin.groovy b/quasar-utils/src/main/groovy/net/corda/plugins/QuasarPlugin.groovy
index 99d0659b11..8fe44c45d6 100644
--- a/quasar-utils/src/main/groovy/net/corda/plugins/QuasarPlugin.groovy
+++ b/quasar-utils/src/main/groovy/net/corda/plugins/QuasarPlugin.groovy
@@ -38,11 +38,16 @@ class QuasarPlugin implements Plugin<Project> {
         def quasarGroup = rootProject.hasProperty('quasar_group') ? rootProject.property('quasar_group') : defaultGroup
         def quasarVersion = rootProject.hasProperty('quasar_version') ? rootProject.property('quasar_version') : defaultVersion
         def quasarClassifier = rootProject.hasProperty('quasar_classifier') ? rootProject.property('quasar_classifier') : defaultClassifier
-        def quasarExclusions = rootProject.hasProperty("quasar_exclusions") ? rootProject.property('quasar_exclusions') : Collections.emptyList()
-        if (!(quasarExclusions instanceof Iterable<?>)) {
+        def quasarPackageExclusions = rootProject.hasProperty("quasar_exclusions") ? rootProject.property('quasar_exclusions') : Collections.emptyList()
+        if (!(quasarPackageExclusions instanceof Iterable<?>)) {
             throw new InvalidUserDataException("quasar_exclusions property must be an Iterable<String>")
         }
-        def quasarExtension = project.extensions.create(QUASAR, QuasarExtension, objects, quasarGroup, quasarVersion, quasarClassifier, quasarExclusions)
+        def quasarClassLoaderExclusions = rootProject.hasProperty("quasar_classloader_exclusions") ? rootProject.property('quasar_classloader_exclusions') : Collections.emptyList()
+        if (!(quasarClassLoaderExclusions instanceof Iterable<?>)) {
+            throw new InvalidUserDataException("quasar_classloader_exclusions property must be an Iterable<String>")
+        }
+        def quasarExtension = project.extensions.create(QUASAR, QuasarExtension, objects,
+                quasarGroup, quasarVersion, quasarClassifier, quasarPackageExclusions, quasarClassLoaderExclusions)
 
         addQuasarDependencies(project, quasarExtension)
         configureQuasarTasks(project, quasarExtension)
diff --git a/quasar-utils/src/test/groovy/net/corda/plugins/QuasarPluginTest.groovy b/quasar-utils/src/test/groovy/net/corda/plugins/QuasarPluginTest.groovy
index 33feaab526..cb79392180 100644
--- a/quasar-utils/src/test/groovy/net/corda/plugins/QuasarPluginTest.groovy
+++ b/quasar-utils/src/test/groovy/net/corda/plugins/QuasarPluginTest.groovy
@@ -20,6 +20,7 @@ class QuasarPluginTest {
 
     @BeforeEach
     void setup() {
+        Utilities.installResource(testProjectDir, "gradle.properties")
         Utilities.installResource(testProjectDir, "settings.gradle")
         Utilities.installResource(testProjectDir, "repositories.gradle")
         Utilities.installResource(testProjectDir, "src/test/java/BasicTest.java")
@@ -445,6 +446,41 @@ test {
         }
     }
 
+    @Test
+    void testExcludeClassLoaders() {
+        def output = runGradleFor """
+plugins {
+    id 'net.corda.plugins.quasar-utils' apply false
+}
+apply plugin: 'net.corda.plugins.quasar-utils'
+apply from: 'repositories.gradle'
+
+dependencies {
+    testImplementation 'junit:junit:4.12'
+}
+
+quasar {
+    version = '0.7.12_r3'
+    excludeClassLoaders = [ 'net.corda.**', 'org.testing.*' ]
+}
+
+jar {
+    enabled = false
+}
+
+test {
+    doLast {
+        allJvmArgs.forEach {
+            println "TEST-JVM: \${it}"
+        }
+    }
+}
+""", "test"
+        assertThat(output).anyMatch {
+            it.startsWith("TEST-JVM: -javaagent:") && it.endsWith('=l(net.corda.**;org.testing.*)')
+        }
+    }
+
     private List<String> runGradleFor(String script, String taskName) {
         def result = runnerFor(script, taskName).build()
         println result.output
diff --git a/quasar-utils/src/test/resources/gradle.properties b/quasar-utils/src/test/resources/gradle.properties
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/quasar-utils/src/test/resources/repositories.gradle b/quasar-utils/src/test/resources/repositories.gradle
index b965e9bb6e..c9e8bc8f12 100644
--- a/quasar-utils/src/test/resources/repositories.gradle
+++ b/quasar-utils/src/test/resources/repositories.gradle
@@ -1,3 +1,6 @@
 repositories {
     mavenCentral()
+    maven {
+        url 'https://software.r3.com/artifactory/corda-dependencies'
+    }
 }