diff --git a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/KtSymbolByFirBuilder.kt b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/KtSymbolByFirBuilder.kt
index a4875f96643..1fea0fa75e5 100644
--- a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/KtSymbolByFirBuilder.kt
+++ b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/KtSymbolByFirBuilder.kt
@@ -8,24 +8,6 @@ package org.jetbrains.kotlin.analysis.api.fir
 import com.intellij.openapi.project.Project
 import com.intellij.psi.JavaPsiFacade
 import com.intellij.psi.search.GlobalSearchScope
-import org.jetbrains.kotlin.analysis.providers.createPackageProvider
-import org.jetbrains.kotlin.builtins.functions.FunctionClassKind
-import org.jetbrains.kotlin.fir.*
-import org.jetbrains.kotlin.fir.declarations.*
-import org.jetbrains.kotlin.fir.declarations.impl.FirFieldImpl
-import org.jetbrains.kotlin.fir.declarations.synthetic.FirSyntheticProperty
-import org.jetbrains.kotlin.fir.java.declarations.FirJavaField
-import org.jetbrains.kotlin.fir.resolve.calls.originalConstructorIfTypeAlias
-import org.jetbrains.kotlin.fir.resolve.getSymbolByLookupTag
-import org.jetbrains.kotlin.fir.resolve.symbolProvider
-import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTag
-import org.jetbrains.kotlin.fir.symbols.ConeTypeParameterLookupTag
-import org.jetbrains.kotlin.fir.symbols.impl.FirBackingFieldSymbol
-import org.jetbrains.kotlin.fir.symbols.impl.FirClassifierSymbol
-import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
-import org.jetbrains.kotlin.fir.types.*
-import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
-import org.jetbrains.kotlin.analysis.low.level.api.fir.api.FirModuleResolveState
 import org.jetbrains.kotlin.analysis.api.KtStarProjectionTypeArgument
 import org.jetbrains.kotlin.analysis.api.KtTypeArgument
 import org.jetbrains.kotlin.analysis.api.KtTypeArgumentWithVariance
@@ -35,7 +17,26 @@ import org.jetbrains.kotlin.analysis.api.fir.types.*
 import org.jetbrains.kotlin.analysis.api.fir.utils.weakRef
 import org.jetbrains.kotlin.analysis.api.symbols.*
 import org.jetbrains.kotlin.analysis.api.tokens.ValidityToken
+import org.jetbrains.kotlin.analysis.api.types.KtSubstitutor
 import org.jetbrains.kotlin.analysis.api.types.KtType
+import org.jetbrains.kotlin.analysis.low.level.api.fir.api.FirModuleResolveState
+import org.jetbrains.kotlin.analysis.providers.createPackageProvider
+import org.jetbrains.kotlin.builtins.functions.FunctionClassKind
+import org.jetbrains.kotlin.fir.*
+import org.jetbrains.kotlin.fir.declarations.*
+import org.jetbrains.kotlin.fir.declarations.impl.FirFieldImpl
+import org.jetbrains.kotlin.fir.declarations.synthetic.FirSyntheticProperty
+import org.jetbrains.kotlin.fir.java.declarations.FirJavaField
+import org.jetbrains.kotlin.fir.resolve.calls.originalConstructorIfTypeAlias
+import org.jetbrains.kotlin.fir.resolve.getSymbolByLookupTag
+import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
+import org.jetbrains.kotlin.fir.resolve.symbolProvider
+import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTag
+import org.jetbrains.kotlin.fir.symbols.ConeTypeParameterLookupTag
+import org.jetbrains.kotlin.fir.symbols.impl.FirClassifierSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
+import org.jetbrains.kotlin.fir.types.*
+import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.types.Variance
@@ -383,6 +384,10 @@ internal class KtSymbolByFirBuilder private constructor(
             ProjectionKind.STAR -> error("KtStarProjectionTypeArgument should not be directly created")
         }
 
+        fun buildSubstitutor(substitutor: ConeSubstitutor): KtSubstitutor {
+            if (substitutor == ConeSubstitutor.Empty) return KtSubstitutor.Empty(token)
+            return KtFirSubstitutor(substitutor, this@KtSymbolByFirBuilder, token)
+        }
     }
 
     companion object {
diff --git a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/types/KtFirSubstitutor.kt b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/types/KtFirSubstitutor.kt
new file mode 100644
index 00000000000..8faa95d6851
--- /dev/null
+++ b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/types/KtFirSubstitutor.kt
@@ -0,0 +1,28 @@
+/*
+ * 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.analysis.api.fir.types
+
+import org.jetbrains.kotlin.analysis.api.fir.KtSymbolByFirBuilder
+import org.jetbrains.kotlin.analysis.api.fir.utils.weakRef
+import org.jetbrains.kotlin.analysis.api.tokens.ValidityToken
+import org.jetbrains.kotlin.analysis.api.types.KtSubstitutor
+import org.jetbrains.kotlin.analysis.api.types.KtType
+import org.jetbrains.kotlin.analysis.api.withValidityAssertion
+import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
+
+internal class KtFirSubstitutor(
+    private val _substitutor: ConeSubstitutor,
+    builder: KtSymbolByFirBuilder,
+    override val token: ValidityToken,
+) : KtSubstitutor {
+    private val builderRef by weakRef(builder)
+    val substitutor: ConeSubstitutor get() = withValidityAssertion { _substitutor }
+
+    override fun substituteOrNull(type: KtType): KtType? = withValidityAssertion {
+        require(type is KtFirType)
+        substitutor.substituteOrNull(type.coneType)?.type?.let { builderRef.typeBuilder.buildKtType(it) }
+    }
+}
\ No newline at end of file
diff --git a/analysis/analysis-api/src/org/jetbrains/kotlin/analysis/api/types/KtSubstitutor.kt b/analysis/analysis-api/src/org/jetbrains/kotlin/analysis/api/types/KtSubstitutor.kt
new file mode 100644
index 00000000000..ab84b69d350
--- /dev/null
+++ b/analysis/analysis-api/src/org/jetbrains/kotlin/analysis/api/types/KtSubstitutor.kt
@@ -0,0 +1,20 @@
+/*
+ * 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.analysis.api.types
+
+import org.jetbrains.kotlin.analysis.api.ValidityTokenOwner
+import org.jetbrains.kotlin.analysis.api.tokens.ValidityToken
+import org.jetbrains.kotlin.analysis.api.withValidityAssertion
+
+
+public interface KtSubstitutor : ValidityTokenOwner {
+    public fun substituteOrSelf(type: KtType): KtType = substituteOrNull(type) ?: type
+    public fun substituteOrNull(type: KtType): KtType?
+
+    public class Empty(override val token: ValidityToken) : KtSubstitutor {
+        override fun substituteOrNull(type: KtType): KtType = withValidityAssertion { type }
+    }
+}