diff --git a/compiler/psi/cls-psi-file-stub-builder/build.gradle.kts b/compiler/psi/cls-psi-file-stub-builder/build.gradle.kts
index 216b1fe6d00..293624131c4 100644
--- a/compiler/psi/cls-psi-file-stub-builder/build.gradle.kts
+++ b/compiler/psi/cls-psi-file-stub-builder/build.gradle.kts
@@ -9,10 +9,10 @@ dependencies {
     api(project(":core:deserialization.common.jvm"))
     api(project(":core:deserialization"))
     implementation(project(":compiler:psi:cls-psi-stub-builder"))
+    implementation(project(":core:deserialization.common.jvm.impl"))
     implementation(project(":core:compiler.common.jvm"))
 
     api(intellijCoreDep()) { includeJars("intellij-core", rootProject = rootProject) }
-
 }
 
 sourceSets {
diff --git a/compiler/psi/cls-psi-file-stub-builder/src/org/jetbrains/kotlin/psi/stubs/file/builder/DirectoryBasedClassFinder.kt b/compiler/psi/cls-psi-file-stub-builder/src/org/jetbrains/kotlin/psi/stubs/file/builder/DirectoryBasedClassFinder.kt
new file mode 100644
index 00000000000..dd3f3bfacec
--- /dev/null
+++ b/compiler/psi/cls-psi-file-stub-builder/src/org/jetbrains/kotlin/psi/stubs/file/builder/DirectoryBasedClassFinder.kt
@@ -0,0 +1,55 @@
+/*
+ * Copyright 2010-2021 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.psi.stubs.file.builder
+
+import com.intellij.openapi.vfs.VirtualFile
+import org.jetbrains.kotlin.load.java.structure.JavaClass
+import org.jetbrains.kotlin.load.java.structure.classId
+import org.jetbrains.kotlin.load.kotlin.KotlinClassFinder
+import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.FqName
+import java.io.InputStream
+
+class DirectoryBasedClassFinder(
+    val packageDirectory: VirtualFile,
+    val directoryPackageFqName: FqName
+) : KotlinClassFinder {
+    override fun findKotlinClassOrContent(javaClass: JavaClass): KotlinClassFinder.Result? = findKotlinClassOrContent(javaClass.classId!!)
+
+    override fun findKotlinClassOrContent(classId: ClassId): KotlinClassFinder.Result? {
+        if (classId.packageFqName != directoryPackageFqName) {
+            return null
+        }
+        val targetName = classId.relativeClassName.pathSegments().joinToString("$", postfix = ".class")
+        val virtualFile = packageDirectory.findChild(targetName)
+        if (virtualFile != null && isKotlinWithCompatibleAbiVersion(virtualFile)) {
+            return IDEKotlinBinaryClassCache.getInstance().getKotlinBinaryClass(virtualFile)?.let(::KotlinClass)
+        }
+        return null
+    }
+
+    // TODO
+    override fun findMetadata(classId: ClassId): InputStream? = null
+
+    // TODO
+    override fun hasMetadataPackage(fqName: FqName): Boolean = false
+
+    // TODO: load built-ins from packageDirectory?
+    override fun findBuiltInsData(packageFqName: FqName): InputStream? = null
+}
+
+/**
+ * Checks if this file is a compiled Kotlin class file ABI-compatible with the current plugin
+ */
+private fun isKotlinWithCompatibleAbiVersion(file: VirtualFile): Boolean {
+    val ideKotlinBinaryClassCache = IDEKotlinBinaryClassCache.getInstance()
+    if (!ideKotlinBinaryClassCache.isKotlinJvmCompiledFile(file)) return false
+
+    val kotlinClass = ideKotlinBinaryClassCache.getKotlinBinaryClassHeaderData(file)
+    return kotlinClass != null && kotlinClass.metadataVersion.isCompatible()
+}
+
+
diff --git a/compiler/psi/cls-psi-file-stub-builder/src/org/jetbrains/kotlin/psi/stubs/file/builder/DirectoryBasedDataFinder.kt b/compiler/psi/cls-psi-file-stub-builder/src/org/jetbrains/kotlin/psi/stubs/file/builder/DirectoryBasedDataFinder.kt
new file mode 100644
index 00000000000..c63f4103b73
--- /dev/null
+++ b/compiler/psi/cls-psi-file-stub-builder/src/org/jetbrains/kotlin/psi/stubs/file/builder/DirectoryBasedDataFinder.kt
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2010-2021 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.psi.stubs.file.builder
+
+import com.intellij.openapi.diagnostic.Logger
+import org.jetbrains.kotlin.load.kotlin.KotlinJvmBinarySourceElement
+import org.jetbrains.kotlin.load.kotlin.findKotlinClass
+import org.jetbrains.kotlin.metadata.jvm.deserialization.JvmProtoBufUtil
+import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.serialization.deserialization.ClassData
+import org.jetbrains.kotlin.serialization.deserialization.ClassDataFinder
+
+class DirectoryBasedDataFinder(
+    val classFinder: DirectoryBasedClassFinder,
+    val log: Logger
+) : ClassDataFinder {
+    override fun findClassData(classId: ClassId): ClassData? {
+        val binaryClass = classFinder.findKotlinClass(classId) ?: return null
+        val classHeader = binaryClass.classHeader
+        val data = classHeader.data
+        if (data == null) {
+            log.error("Annotation data missing for ${binaryClass.classId}")
+            return null
+        }
+        val strings = classHeader.strings
+        if (strings == null) {
+            log.error("String table not found in class ${binaryClass.classId}")
+            return null
+        }
+
+        val (nameResolver, classProto) = JvmProtoBufUtil.readClassDataFrom(data, strings)
+        return ClassData(nameResolver, classProto, classHeader.metadataVersion, KotlinJvmBinarySourceElement(binaryClass))
+    }
+}
\ No newline at end of file