diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/DeepCopyIrTreeWithDeclarations.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/DeepCopyIrTreeWithDeclarations.kt
index 30859ffb09f..77e77478e56 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/DeepCopyIrTreeWithDeclarations.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/DeepCopyIrTreeWithDeclarations.kt
@@ -1,29 +1,19 @@
 /*
- * Copyright 2010-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * 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.backend.common
 
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.expressions.IrLoop
-import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.util.DeepCopyIrTreeWithSymbols
+import org.jetbrains.kotlin.ir.util.DeepCopySymbolRemapper
+import org.jetbrains.kotlin.ir.util.DeepCopyTypeRemapper
+import org.jetbrains.kotlin.ir.util.NullDescriptorsRemapper
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
 
 @Suppress("UNCHECKED_CAST")
-@OptIn(ObsoleteDescriptorBasedAPI::class)
 fun <T : IrElement> T.deepCopyWithVariables(): T {
     val symbolsRemapper = DeepCopySymbolRemapper(NullDescriptorsRemapper)
     acceptVoid(symbolsRemapper)
@@ -38,4 +28,4 @@ fun <T : IrElement> T.deepCopyWithVariables(): T {
             },
             null
     ) as T
-}
\ No newline at end of file
+}
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrInlineUtils.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrInlineUtils.kt
index 44671ca21a8..9598b50078c 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrInlineUtils.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrInlineUtils.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * 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.
  */
 
@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.backend.common.ir
 
 import org.jetbrains.kotlin.backend.common.lower.VariableRemapper
 import org.jetbrains.kotlin.ir.IrStatement
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrReturnImpl
@@ -83,4 +82,4 @@ private fun IrBody.move(
 fun IrFunction.inline(target: IrDeclarationParent, arguments: List<IrValueDeclaration> = listOf()): IrReturnableBlock =
     IrReturnableBlockImpl(startOffset, endOffset, returnType, IrReturnableBlockSymbolImpl(), null, symbol).apply {
         statements += body!!.move(this@inline, target, symbol, valueParameters.zip(arguments).toMap()).statements
-    }
\ No newline at end of file
+    }
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt
index 358e6b8fdfe..ccc4a17a685 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt
@@ -12,7 +12,6 @@ import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
 import org.jetbrains.kotlin.descriptors.DescriptorVisibility
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.ir.IrElement
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.builders.declarations.addConstructor
 import org.jetbrains.kotlin.ir.builders.declarations.buildReceiverParameter
 import org.jetbrains.kotlin.ir.builders.declarations.buildTypeParameter
@@ -26,8 +25,8 @@ import org.jetbrains.kotlin.ir.overrides.FakeOverrideBuilderStrategy
 import org.jetbrains.kotlin.ir.overrides.IrOverridingUtil
 import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
-import org.jetbrains.kotlin.ir.symbols.impl.IrPropertySymbolImpl
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
+import org.jetbrains.kotlin.ir.symbols.impl.IrPropertySymbolImpl
 import org.jetbrains.kotlin.ir.symbols.impl.IrSimpleFunctionSymbolImpl
 import org.jetbrains.kotlin.ir.symbols.impl.IrValueParameterSymbolImpl
 import org.jetbrains.kotlin.ir.types.*
@@ -485,7 +484,6 @@ fun IrClass.addFakeOverrides(irBuiltIns: IrBuiltIns, implementedMembers: List<Ir
         .forEach { addChild(it) }
 }
 
-@OptIn(ObsoleteDescriptorBasedAPI::class)
 fun IrFactory.createStaticFunctionWithReceivers(
         irParent: IrDeclarationParent,
         name: Name,
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/LowerUtils.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/LowerUtils.kt
index cf606ccaada..bb2a2dd5a74 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/LowerUtils.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/LowerUtils.kt
@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * 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.backend.common.lower
@@ -21,7 +10,6 @@ import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.impl.ValueParameterDescriptorImpl
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.IrStatement
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.*
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BridgesConstruction.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BridgesConstruction.kt
index 5cf0486cc77..da3b4300a67 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BridgesConstruction.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BridgesConstruction.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * 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.
  */
 
@@ -11,7 +11,6 @@ import org.jetbrains.kotlin.backend.common.bridges.generateBridges
 import org.jetbrains.kotlin.backend.common.ir.*
 import org.jetbrains.kotlin.backend.common.lower.*
 import org.jetbrains.kotlin.descriptors.Modality
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsCommonBackendContext
 import org.jetbrains.kotlin.ir.backend.js.JsLoweredDeclarationOrigin
@@ -44,7 +43,6 @@ import org.jetbrains.kotlin.ir.util.*
 //            fun foo(t: Any?) = foo(t as Int)  // Constructed bridge
 //          }
 //
-@OptIn(ObsoleteDescriptorBasedAPI::class)
 abstract class BridgesConstruction(val context: JsCommonBackendContext) : DeclarationTransformer {
 
     private val specialBridgeMethods = SpecialBridgeMethods(context)
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsInnerClassesSupport.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsInnerClassesSupport.kt
index 245decfe249..f51092d8de8 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsInnerClassesSupport.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsInnerClassesSupport.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * 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.
  */
 
@@ -10,7 +10,6 @@ import org.jetbrains.kotlin.backend.common.ir.copyTo
 import org.jetbrains.kotlin.backend.common.ir.copyTypeParametersFrom
 import org.jetbrains.kotlin.backend.common.lower.InnerClassesSupport
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.backend.js.JsMapping
 import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder.SYNTHESIZED_DECLARATION
 import org.jetbrains.kotlin.ir.backend.js.utils.Namer
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/VarargLowering.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/VarargLowering.kt
index f8018f17c9b..5836951c01a 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/VarargLowering.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/VarargLowering.kt
@@ -1,12 +1,11 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * 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.ir.backend.js.lower
 
 import org.jetbrains.kotlin.backend.common.BodyLoweringPass
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
@@ -33,7 +32,6 @@ private class VarargTransformer(
 
     fun IrType.getInlinedClass() = context.inlineClassesUtils.getInlinedClass(this)
 
-    @OptIn(ObsoleteDescriptorBasedAPI::class)
     private fun List<IrExpression>.toArrayLiteral(type: IrType, varargElementType: IrType): IrExpression {
 
         // TODO: Use symbols when builtins symbol table is fixes
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/MultiModuleSupport.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/MultiModuleSupport.kt
index d7afc286f6f..b5cdf4f6c35 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/MultiModuleSupport.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/MultiModuleSupport.kt
@@ -5,7 +5,6 @@
 
 package org.jetbrains.kotlin.ir.backend.js.transformers.irToJs
 
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.utils.IrNamer
@@ -117,7 +116,6 @@ fun buildCrossModuleReferenceInfo(modules: Iterable<IrModuleFragment>): CrossMod
     return CrossModuleReferenceInfoImpl(map)
 }
 
-@OptIn(ObsoleteDescriptorBasedAPI::class)
 fun breakCrossModuleFieldAccess(
     context: JsIrBackendContext,
     modules: Iterable<IrModuleFragment>
@@ -214,4 +212,4 @@ val IrModuleFragment.safeName: String
         if (result.endsWith('>')) result = result.substring(0, result.length - 1)
 
         return sanitizeName("kotlin-$result")
-    }
\ No newline at end of file
+    }