diff --git a/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/AllOpenClassGenerator.kt b/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/AllOpenClassGenerator.kt
new file mode 100644
index 00000000000..dbb5a646920
--- /dev/null
+++ b/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/AllOpenClassGenerator.kt
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.allopen
+
+import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.descriptors.Modality
+import org.jetbrains.kotlin.descriptors.Visibilities
+import org.jetbrains.kotlin.fir.FirAnnotationContainer
+import org.jetbrains.kotlin.fir.FirEffectiveVisibility
+import org.jetbrains.kotlin.fir.FirEffectiveVisibilityImpl
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.declarations.FirDeclaration
+import org.jetbrains.kotlin.fir.declarations.FirFile
+import org.jetbrains.kotlin.fir.declarations.FirRegularClass
+import org.jetbrains.kotlin.fir.declarations.builder.buildClassImpl
+import org.jetbrains.kotlin.fir.declarations.impl.FirResolvedDeclarationStatusImpl
+import org.jetbrains.kotlin.fir.extensions.AnnotationFqn
+import org.jetbrains.kotlin.fir.extensions.FirClassGenerationExtension
+import org.jetbrains.kotlin.fir.resolve.firProvider
+import org.jetbrains.kotlin.fir.resolve.impl.FirProviderImpl
+import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
+import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+
+class AllOpenClassGenerator(session: FirSession) : FirClassGenerationExtension(session) {
+    override fun <T> generateClass(
+        containingFile: FirFile,
+        annotatedDeclaration: T
+    ): List<GeneratedClass> where T : FirDeclaration, T : FirAnnotationContainer {
+        if (annotatedDeclaration !is FirRegularClass) return emptyList()
+        val klass = buildClassImpl {
+            session = this@AllOpenClassGenerator.session
+            origin = FirDeclarationOrigin.Plugin(AllOpenPluginKey)
+            status = FirResolvedDeclarationStatusImpl(Visibilities.PUBLIC, FirEffectiveVisibilityImpl.Public, Modality.FINAL)
+            classKind = ClassKind.OBJECT
+            scopeProvider = (session.firProvider as FirProviderImpl).kotlinScopeProvider
+            name = Name.identifier("Foo${annotatedDeclaration.name.identifier}")
+            symbol = FirRegularClassSymbol(ClassId(containingFile.packageFqName, name))
+            superTypeRefs += session.builtinTypes.anyType
+        }
+        return listOf(GeneratedClass(klass, containingFile))
+    }
+
+    override val annotations: Set<AnnotationFqn> =
+        setOf(FqName("org.jetbrains.kotlin.fir.allopen.WithClass"))
+
+    override val metaAnnotations: Set<AnnotationFqn> = emptySet()
+}
\ No newline at end of file
diff --git a/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/AllOpenPluginKey.kt b/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/AllOpenPluginKey.kt
new file mode 100644
index 00000000000..719a615d562
--- /dev/null
+++ b/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/AllOpenPluginKey.kt
@@ -0,0 +1,10 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.allopen
+
+import org.jetbrains.kotlin.fir.declarations.FirPluginMarker
+
+object AllOpenPluginKey : FirPluginMarker()
\ No newline at end of file
diff --git a/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/FirAllOpenComponentRegistrar.kt b/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/FirAllOpenComponentRegistrar.kt
index 0161e9d1496..497fdfcbb51 100644
--- a/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/FirAllOpenComponentRegistrar.kt
+++ b/compiler/fir/plugins/allopen-plugin/src/org/jetbrains/kotlin/fir/allopen/FirAllOpenComponentRegistrar.kt
@@ -10,5 +10,6 @@ import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
 class FirAllOpenComponentRegistrar : FirExtensionRegistrar() {
     override fun ExtensionRegistrarContext.configurePlugin() {
         +::AllOpenStatusTransformer
+        +::AllOpenClassGenerator
     }
 }
\ No newline at end of file
diff --git a/compiler/fir/plugins/allopen-plugin/testData/classGen/simple.kt b/compiler/fir/plugins/allopen-plugin/testData/classGen/simple.kt
new file mode 100644
index 00000000000..f7dfb4041df
--- /dev/null
+++ b/compiler/fir/plugins/allopen-plugin/testData/classGen/simple.kt
@@ -0,0 +1,7 @@
+import org.jetbrains.kotlin.fir.allopen.WithClass
+import org.jetbrains.kotlin.fir.allopen.AllOpen
+
+@WithClass
+class A {
+
+}
\ No newline at end of file
diff --git a/compiler/fir/plugins/allopen-plugin/testData/classGen/simple.txt b/compiler/fir/plugins/allopen-plugin/testData/classGen/simple.txt
new file mode 100644
index 00000000000..ac36df9a173
--- /dev/null
+++ b/compiler/fir/plugins/allopen-plugin/testData/classGen/simple.txt
@@ -0,0 +1,9 @@
+FILE: simple.kt
+    @R|org/jetbrains/kotlin/fir/allopen/WithClass|() public final class A : R|kotlin/Any| {
+        public constructor(): R|A| {
+            super<R|kotlin/Any|>()
+        }
+
+    }
+    public final object FooA : R|kotlin/Any| {
+    }
diff --git a/compiler/fir/plugins/allopen-plugin/tests/org/jetbrains/kotlin/fir/allopen/FirAllOpenDiagnosticTestGenerated.java b/compiler/fir/plugins/allopen-plugin/tests/org/jetbrains/kotlin/fir/allopen/FirAllOpenDiagnosticTestGenerated.java
index 33c4f80a469..5f434d3a4f4 100644
--- a/compiler/fir/plugins/allopen-plugin/tests/org/jetbrains/kotlin/fir/allopen/FirAllOpenDiagnosticTestGenerated.java
+++ b/compiler/fir/plugins/allopen-plugin/tests/org/jetbrains/kotlin/fir/allopen/FirAllOpenDiagnosticTestGenerated.java
@@ -28,6 +28,24 @@ public class FirAllOpenDiagnosticTestGenerated extends AbstractFirAllOpenDiagnos
         KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/plugins/allopen-plugin/testData"), Pattern.compile("^(.+)\\.kt$"), null, true);
     }
 
+    @TestMetadata("compiler/fir/plugins/allopen-plugin/testData/classGen")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class ClassGen extends AbstractFirAllOpenDiagnosticTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, this, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInClassGen() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/plugins/allopen-plugin/testData/classGen"), Pattern.compile("^(.+)\\.kt$"), null, true);
+        }
+
+        @TestMetadata("simple.kt")
+        public void testSimple() throws Exception {
+            runTest("compiler/fir/plugins/allopen-plugin/testData/classGen/simple.kt");
+        }
+    }
+
     @TestMetadata("compiler/fir/plugins/allopen-plugin/testData/status")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)