diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/ErrorExpressionLowering.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/ErrorExpressionLowering.kt
new file mode 100644
index 00000000000..95630519abf
--- /dev/null
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/ErrorExpressionLowering.kt
@@ -0,0 +1,68 @@
+/*
+ * 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
+
+import org.jetbrains.kotlin.backend.common.BodyLoweringPass
+import org.jetbrains.kotlin.backend.common.CommonBackendContext
+import org.jetbrains.kotlin.backend.common.DeclarationTransformer
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.declarations.IrErrorDeclaration
+import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.expressions.impl.IrCompositeImpl
+import org.jetbrains.kotlin.ir.types.IrErrorType
+import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
+import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
+
+abstract class ErrorDeclarationLowering : DeclarationTransformer {
+    abstract fun transformErrorDeclaration(declaration: IrErrorDeclaration): IrDeclaration
+    override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
+        if (declaration is IrErrorDeclaration) return listOf(transformErrorDeclaration(declaration))
+        return null
+    }
+}
+
+abstract class ErrorExpressionLowering(context: CommonBackendContext) : BodyLoweringPass {
+
+    protected val nothingType = context.irBuiltIns.nothingType
+
+    abstract fun transformErrorExpression(expression: IrExpression, nodeKind: String): IrExpression
+
+    override fun lower(irBody: IrBody, container: IrDeclaration) {
+        irBody.transformChildrenVoid(object : IrElementTransformerVoid() {
+
+            override fun visitErrorExpression(expression: IrErrorExpression): IrExpression {
+                return transformErrorExpression(expression, "Error Expression")
+            }
+
+            override fun visitErrorCallExpression(expression: IrErrorCallExpression): IrExpression {
+                expression.transformChildrenVoid(this)
+                val statements = mutableListOf<IrExpression>().apply {
+                    expression.explicitReceiver?.let { add(it) }
+                    addAll(expression.arguments)
+                    add(transformErrorExpression(expression, "Error Call"))
+                }
+                return expression.run {
+                    IrCompositeImpl(startOffset, endOffset, nothingType, null, statements)
+                }
+            }
+
+            override fun visitTypeOperator(expression: IrTypeOperatorCall): IrExpression {
+                expression.transformChildrenVoid(this)
+                if (expression.typeOperand is IrErrorType) {
+                    return expression.run {
+                        IrCompositeImpl(
+                            startOffset, endOffset, nothingType, null, listOf(
+                                argument, transformErrorExpression(this, "Error Type")
+                            )
+                        )
+                    }
+                }
+
+                return expression
+            }
+        })
+    }
+}
\ No newline at end of file
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 9f78f1ceb56..eccd135c131 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
@@ -28,6 +28,7 @@ import org.jetbrains.kotlin.ir.symbols.impl.DescriptorlessExternalPackageFragmen
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.types.impl.IrDynamicTypeImpl
 import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.js.config.ErrorTolerancePolicy
 import org.jetbrains.kotlin.js.config.JSConfigurationKeys
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
@@ -59,6 +60,7 @@ class JsIrBackendContext(
     override val irFactory: IrFactory = PersistentIrFactory
 
     val devMode = configuration[JSConfigurationKeys.DEVELOPER_MODE] ?: false
+    val errorPolicy = configuration[JSConfigurationKeys.ERROR_TOLERANCE_POLICY] ?: ErrorTolerancePolicy.DEFAULT
 
     val externalPackageFragment = mutableMapOf<IrFileSymbol, IrFile>()
     val externalDeclarations = hashSetOf<IrDeclaration>()
@@ -229,6 +231,9 @@ class JsIrBackendContext(
 
     // classes forced to be loaded
 
+    val errorCodeSymbol: IrSimpleFunctionSymbol? =
+        if (errorPolicy.allowErrors) symbolTable.referenceSimpleFunction(getJsInternalFunction("errorCode")) else null
+
     val primitiveClassesObject = getIrClass(FqName("kotlin.reflect.js.internal.PrimitiveClasses"))
 
     val throwableClass = getIrClass(JsIrBackendContext.KOTLIN_PACKAGE_FQN.child(Name.identifier("Throwable")))
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsErrorExpressionLowering.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsErrorExpressionLowering.kt
new file mode 100644
index 00000000000..dad97947c20
--- /dev/null
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsErrorExpressionLowering.kt
@@ -0,0 +1,63 @@
+/*
+ * 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.lower.ErrorDeclarationLowering
+import org.jetbrains.kotlin.backend.common.lower.ErrorExpressionLowering
+import org.jetbrains.kotlin.ir.IrElement
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.builders.declarations.buildFun
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.declarations.IrErrorDeclaration
+import org.jetbrains.kotlin.ir.expressions.IrErrorExpression
+import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
+import org.jetbrains.kotlin.name.Name
+
+class JsErrorDeclarationLowering(context: JsIrBackendContext) : ErrorDeclarationLowering() {
+    private val nothingType = context.irBuiltIns.nothingType
+    private val stringType = context.irBuiltIns.stringType
+    private val errorSymbol = context.errorCodeSymbol
+    private val irFactory = context.irFactory
+
+    override fun transformErrorDeclaration(declaration: IrErrorDeclaration): IrDeclaration {
+        require(errorSymbol != null) { "Should be non-null if errors are allowed" }
+        return irFactory.buildFun {
+            updateFrom(declaration)
+            returnType = nothingType
+            name = Name.identifier("\$errorDeclaration")
+        }.also {
+            it.parent = declaration.parent
+            it.body = irFactory.createBlockBody(it.startOffset, it.endOffset) {
+                statements += IrCallImpl(startOffset, endOffset, nothingType, errorSymbol, 0, 1, null, null).apply {
+                    putValueArgument(0, IrConstImpl.string(startOffset, endOffset, stringType, "ERROR DECLARATION"))
+                }
+            }
+        }
+    }
+}
+
+class JsErrorExpressionLowering(context: JsIrBackendContext) : ErrorExpressionLowering(context) {
+
+    private val stringType = context.irBuiltIns.nothingType
+    private val errorSymbol = context.errorCodeSymbol
+
+    override fun transformErrorExpression(expression: IrExpression, nodeKind: String): IrExpression {
+        val errorExpression = expression as? IrErrorExpression
+        val description = errorExpression?.let { "$nodeKind: ${it.description}" } ?: nodeKind
+        return buildThrowError(expression, description)
+    }
+
+    private fun buildThrowError(element: IrElement, description: String): IrExpression {
+        require(errorSymbol != null) { "Should be non-null if errors are allowed" }
+        return element.run {
+            IrCallImpl(startOffset, endOffset, nothingType, errorSymbol, 0, 1, null, null).apply {
+                putValueArgument(0, IrConstImpl.string(startOffset, endOffset, stringType, description))
+            }
+        }
+    }
+}
\ No newline at end of file