diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt
index cb032dbcd7f..c401c90df1b 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt
@@ -11,10 +11,7 @@ import org.jetbrains.kotlin.backend.common.ir.Symbols
 import org.jetbrains.kotlin.backend.js.JsDeclarationFactory
 import org.jetbrains.kotlin.builtins.PrimitiveType
 import org.jetbrains.kotlin.config.CompilerConfiguration
-import org.jetbrains.kotlin.descriptors.ClassDescriptor
-import org.jetbrains.kotlin.descriptors.ModuleDescriptor
-import org.jetbrains.kotlin.descriptors.PropertyDescriptor
-import org.jetbrains.kotlin.descriptors.SimpleFunctionDescriptor
+import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.impl.EmptyPackageFragmentDescriptor
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation
 import org.jetbrains.kotlin.ir.IrElement
@@ -25,6 +22,7 @@ import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
 import org.jetbrains.kotlin.ir.backend.js.lower.CallableReferenceKey
 import org.jetbrains.kotlin.ir.backend.js.utils.OperatorNames
 import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.declarations.impl.IrExternalPackageFragmentImpl
 import org.jetbrains.kotlin.ir.declarations.impl.IrFileImpl
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
 import org.jetbrains.kotlin.ir.symbols.*
@@ -60,11 +58,34 @@ class JsIrBackendContext(
 
     val devMode = configuration[JSConfigurationKeys.DEVELOPER_MODE] ?: false
 
-    var externalPackageFragment = mutableMapOf<IrFileSymbol, IrFile>()
-    lateinit var bodilessBuiltInsPackageFragment: IrPackageFragment
+    val externalPackageFragment = mutableMapOf<IrFileSymbol, IrFile>()
+    val bodilessBuiltInsPackageFragment: IrPackageFragment = run {
 
-    val externalNestedClasses = mutableListOf<IrClass>()
-    val packageLevelJsModules = mutableListOf<IrFile>()
+        class DescriptorlessExternalPackageFragmentSymbol : IrExternalPackageFragmentSymbol {
+            override val descriptor: PackageFragmentDescriptor
+                get() = error("Operation is unsupported")
+
+            private var _owner: IrExternalPackageFragment? = null
+            override val owner get() = _owner!!
+
+            override var uniqId: UniqId
+                get() = error("Operation is unsupported")
+                set(value) { error("Operation is unsupported") }
+
+            override val isBound get() = _owner != null
+
+            override fun bind(owner: IrExternalPackageFragment) {
+                _owner = owner
+            }
+        }
+
+        IrExternalPackageFragmentImpl(
+            DescriptorlessExternalPackageFragmentSymbol(),
+            FqName("kotlin")
+        )
+    }
+
+    val packageLevelJsModules = mutableSetOf<IrFile>()
     val declarationLevelJsModules = mutableListOf<IrDeclarationWithName>()
 
     val internalPackageFragmentDescriptor = EmptyPackageFragmentDescriptor(builtIns.builtInsModule, FqName("kotlin.js.internal"))
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/MoveBodilessDeclarationsToSeparatePlace.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/MoveBodilessDeclarationsToSeparatePlace.kt
index fb6df3de1aa..997a5174d6f 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/MoveBodilessDeclarationsToSeparatePlace.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/MoveBodilessDeclarationsToSeparatePlace.kt
@@ -5,20 +5,18 @@
 
 package org.jetbrains.kotlin.ir.backend.js.lower
 
+import org.jetbrains.kotlin.backend.common.DeclarationTransformer
 import org.jetbrains.kotlin.backend.common.ir.addChild
 import org.jetbrains.kotlin.descriptors.PackageFragmentDescriptor
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.utils.getJsModule
 import org.jetbrains.kotlin.ir.backend.js.utils.getJsQualifier
 import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.declarations.impl.IrExternalPackageFragmentImpl
 import org.jetbrains.kotlin.ir.declarations.impl.IrFileImpl
-import org.jetbrains.kotlin.ir.symbols.IrExternalPackageFragmentSymbol
 import org.jetbrains.kotlin.ir.symbols.IrFileSymbol
 import org.jetbrains.kotlin.ir.util.UniqId
 import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
 import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
-import org.jetbrains.kotlin.ir.util.transformFlat
 import org.jetbrains.kotlin.name.FqName
 
 private val BODILESS_BUILTIN_CLASSES = listOf(
@@ -43,24 +41,6 @@ private val BODILESS_BUILTIN_CLASSES = listOf(
     "kotlin.Function"
 ).map { FqName(it) }.toSet()
 
-private class DescriptorlessExternalPackageFragmentSymbol : IrExternalPackageFragmentSymbol {
-    override val descriptor: PackageFragmentDescriptor
-        get() = error("Operation is unsupported")
-
-    private var _owner: IrExternalPackageFragment? = null
-    override val owner get() = _owner!!
-
-    override var uniqId: UniqId
-        get() = error("Operation is unsupported")
-        set(value) { error("Operation is unsupported") }
-
-    override val isBound get() = _owner != null
-
-    override fun bind(owner: IrExternalPackageFragment) {
-        _owner = owner
-    }
-}
-
 private class DescriptorlessIrFileSymbol : IrFileSymbol {
     override fun bind(owner: IrFile) {
         _owner = owner
@@ -79,33 +59,22 @@ private class DescriptorlessIrFileSymbol : IrFileSymbol {
     override val isBound get() = _owner != null
 }
 
+private fun isBuiltInClass(declaration: IrDeclaration): Boolean =
+    declaration is IrClass && declaration.fqNameWhenAvailable in BODILESS_BUILTIN_CLASSES
 
-fun moveBodilessDeclarationsToSeparatePlace(context: JsIrBackendContext, module: IrModuleFragment) {
-
-    val bodilessBuiltInsPackageFragment = IrExternalPackageFragmentImpl(
-        DescriptorlessExternalPackageFragmentSymbol(),
-        FqName("kotlin")
-    )
-
-    context.bodilessBuiltInsPackageFragment = bodilessBuiltInsPackageFragment
-
-    fun isBuiltInClass(declaration: IrDeclaration): Boolean =
-        declaration is IrClass && declaration.fqNameWhenAvailable in BODILESS_BUILTIN_CLASSES
-
-    fun collectExternalClasses(container: IrDeclarationContainer, includeCurrentLevel: Boolean): List<IrClass> {
-        val externalClasses =
-            container.declarations.filterIsInstance<IrClass>().filter { it.isEffectivelyExternal() }
-
-        val nestedExternalClasses =
-            externalClasses.flatMap { collectExternalClasses(it, true) }
-
-        return if (includeCurrentLevel)
-            externalClasses + nestedExternalClasses
-        else
-            nestedExternalClasses
+fun moveBodilessDeclarationsToSeparatePlace(context: JsIrBackendContext, moduleFragment: IrModuleFragment) {
+    MoveBodilessDeclarationsToSeparatePlaceLowering(context).let { moveBodiless ->
+        moduleFragment.files.forEach {
+            moveBodiless.lower(it)
+        }
     }
+}
+
+class MoveBodilessDeclarationsToSeparatePlaceLowering(private val context: JsIrBackendContext) : DeclarationTransformer {
+
+    override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
+        val irFile = declaration.parent as? IrFile ?: return null
 
-    fun lowerFile(irFile: IrFile): IrFile? {
         val externalPackageFragment by lazy {
             context.externalPackageFragment.getOrPut(irFile.symbol) {
                 IrFileImpl(fileEntry = irFile.fileEntry, fqName = irFile.fqName, symbol = DescriptorlessIrFileSymbol()).also {
@@ -114,33 +83,30 @@ fun moveBodilessDeclarationsToSeparatePlace(context: JsIrBackendContext, module:
             }
         }
 
-        context.externalNestedClasses += collectExternalClasses(irFile, includeCurrentLevel = false)
-
         if (irFile.getJsModule() != null || irFile.getJsQualifier() != null) {
-            context.packageLevelJsModules.add(irFile)
-            return null
-        }
+            externalPackageFragment.declarations += declaration
+            declaration.parent = externalPackageFragment
 
-        val it = irFile.declarations.iterator()
+            context.packageLevelJsModules += externalPackageFragment
 
-        while (it.hasNext()) {
-            val d = it.next() as? IrDeclarationWithName ?: continue
+            return emptyList()
+        } else {
+            val d = declaration as? IrDeclarationWithName ?: return null
 
             if (isBuiltInClass(d)) {
-                it.remove()
-                bodilessBuiltInsPackageFragment.addChild(d)
+                context.bodilessBuiltInsPackageFragment.addChild(d)
+                return emptyList()
             } else if (d.isEffectivelyExternal()) {
                 if (d.getJsModule() != null)
                     context.declarationLevelJsModules.add(d)
 
-                it.remove()
-                externalPackageFragment.addChild(d)
-            }
-        }
-        return irFile
-    }
+                externalPackageFragment.declarations += d
+                d.parent = externalPackageFragment
 
-    module.files.transformFlat { irFile ->
-        listOfNotNull(lowerFile(irFile))
+                return emptyList()
+            }
+
+            return null
+        }
     }
-}
+}
\ No newline at end of file