diff --git a/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/DataClassMembersGenerator.kt b/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/DataClassMembersGenerator.kt
index 30f536003f4..64581c7d642 100644
--- a/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/DataClassMembersGenerator.kt
+++ b/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/DataClassMembersGenerator.kt
@@ -21,8 +21,9 @@ import org.jetbrains.kotlin.backend.common.DataClassMethodGenerator
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.builders.*
-import org.jetbrains.kotlin.ir.declarations.impl.IrClassImpl
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
+import org.jetbrains.kotlin.ir.declarations.IrFunction
+import org.jetbrains.kotlin.ir.declarations.impl.IrClassImpl
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.mapValueParameters
 import org.jetbrains.kotlin.psi.KtClassOrObject
@@ -42,7 +43,11 @@ class DataClassMembersGenerator(
         override val context: GeneratorContext,
         val irClass: IrClassImpl
 ) : Generator, DataClassMethodGenerator(ktClassOrObject, context.bindingContext) {
-    private inline fun buildMember(function: FunctionDescriptor, psiElement: PsiElement? = null, body: IrMemberFunctionBuilder.() -> Unit) {
+    private inline fun buildMember(
+            function: FunctionDescriptor,
+            psiElement: PsiElement? = null,
+            body: IrMemberFunctionBuilder.(IrFunction) -> Unit
+    ) {
         IrMemberFunctionBuilder(
                 context, irClass, function, IrDeclarationOrigin.GENERATED_DATA_CLASS_MEMBER,
                 psiElement?.startOffset ?: UNDEFINED_OFFSET, psiElement?.endOffset ?: UNDEFINED_OFFSET
@@ -65,6 +70,10 @@ class DataClassMembersGenerator(
                                    throw AssertionError("Data class should have a primary constructor: $classDescriptor")
 
         buildMember(function) {
+            function.valueParameters.forEach { parameter ->
+                val property = getOrFail(BindingContext.VALUE_PARAMETER_AS_PROPERTY, parameter)
+                putDefault(parameter, irGet(irThis(), property))
+            }
             +irReturn(irCall(dataClassConstructor).mapValueParameters { irGet(function.valueParameters[it.index]) })
         }
     }
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/ExpressionHelpers.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/ExpressionHelpers.kt
index b11a7bdc99a..b2b62b959b6 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/ExpressionHelpers.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/ExpressionHelpers.kt
@@ -51,6 +51,9 @@ fun <T : IrElement> IrStatementsBuilder<T>.defineTemporaryVar(value: IrExpressio
     return temporary.descriptor
 }
 
+fun IrBuilderWithScope.irExprBody(value: IrExpression) =
+        IrExpressionBodyImpl(startOffset, endOffset, value)
+
 fun IrBuilderWithScope.irReturn(value: IrExpression) =
         IrReturnImpl(startOffset, endOffset, context.builtIns.nothingType, scope.assertCastOwner(), value)
 
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrBuilder.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrBuilder.kt
index 2612c5b475c..84798aed078 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrBuilder.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrBuilder.kt
@@ -49,7 +49,7 @@ abstract class IrStatementsBuilder<out T : IrElement>(
     }
 
     protected abstract fun addStatement(irStatement: IrStatement)
-    protected abstract fun doBuild(): T
+    abstract fun doBuild(): T
 }
 
 open class IrBlockBodyBuilder(
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrMemberFunctionBuilder.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrMemberFunctionBuilder.kt
index 74ada793237..fe0eb258ce9 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrMemberFunctionBuilder.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/IrMemberFunctionBuilder.kt
@@ -17,10 +17,13 @@
 package org.jetbrains.kotlin.ir.builders
 
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.declarations.impl.IrClassImpl
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
+import org.jetbrains.kotlin.ir.declarations.IrFunction
 import org.jetbrains.kotlin.ir.declarations.impl.IrFunctionImpl
+import org.jetbrains.kotlin.ir.expressions.IrExpression
 
 class IrMemberFunctionBuilder(
         context: IrGeneratorContext,
@@ -30,10 +33,16 @@ class IrMemberFunctionBuilder(
         startOffset: Int = UNDEFINED_OFFSET,
         endOffset: Int = UNDEFINED_OFFSET
 ) : IrBlockBodyBuilder(context, Scope(function), startOffset, endOffset) {
-    inline fun addToClass(body: IrMemberFunctionBuilder.() -> Unit) {
-        val irFunction = IrFunctionImpl(startOffset, endOffset, origin, function)
-        body()
+    lateinit var irFunction: IrFunction
+
+    inline fun addToClass(body: IrMemberFunctionBuilder.(IrFunction) -> Unit) {
+        irFunction = IrFunctionImpl(startOffset, endOffset, origin, function)
+        body(irFunction)
         irFunction.body = doBuild()
         irClass.addMember(irFunction)
     }
+
+    fun putDefault(parameter: ValueParameterDescriptor, value: IrExpression) {
+        irFunction.putDefault(parameter, irExprBody(value))
+    }
 }
\ No newline at end of file
diff --git a/compiler/testData/ir/irText/classes/dataClasses.txt b/compiler/testData/ir/irText/classes/dataClasses.txt
index c97e0a41452..e6fe2245874 100644
--- a/compiler/testData/ir/irText/classes/dataClasses.txt
+++ b/compiler/testData/ir/irText/classes/dataClasses.txt
@@ -47,6 +47,15 @@ FILE /dataClasses.kt
           CALL '<get-z>(): Any' type=kotlin.Any origin=GET_PROPERTY
             $this: GET_VAR '<receiver: Test1>' type=Test1 origin=null
     FUN GENERATED_DATA_CLASS_MEMBER public final fun copy(x: kotlin.Int = ..., y: kotlin.String = ..., z: kotlin.Any = ...): Test1
+      x: EXPRESSION_BODY
+        CALL '<get-x>(): Int' type=kotlin.Int origin=GET_PROPERTY
+          $this: GET_VAR '<receiver: Test1>' type=Test1 origin=null
+      y: EXPRESSION_BODY
+        CALL '<get-y>(): String' type=kotlin.String origin=GET_PROPERTY
+          $this: GET_VAR '<receiver: Test1>' type=Test1 origin=null
+      z: EXPRESSION_BODY
+        CALL '<get-z>(): Any' type=kotlin.Any origin=GET_PROPERTY
+          $this: GET_VAR '<receiver: Test1>' type=Test1 origin=null
       BLOCK_BODY
         RETURN type=kotlin.Nothing from='copy(Int = ..., String = ..., Any = ...): Test1'
           CALL 'constructor Test1(Int, String, Any)' type=Test1 origin=null