diff --git a/idea/idea-gradle/tests/org/jetbrains/kotlin/idea/codeInsight/gradle/GradleConfiguratorTest.kt b/idea/idea-gradle/tests/org/jetbrains/kotlin/idea/codeInsight/gradle/GradleConfiguratorTest.kt
index c455de5c839..ee0820be00d 100644
--- a/idea/idea-gradle/tests/org/jetbrains/kotlin/idea/codeInsight/gradle/GradleConfiguratorTest.kt
+++ b/idea/idea-gradle/tests/org/jetbrains/kotlin/idea/codeInsight/gradle/GradleConfiguratorTest.kt
@@ -594,6 +594,21 @@ class GradleConfiguratorTest : GradleImportingTestCase() {
         }
     }
 
+    @Test
+    fun testEnableFeatureSupportGSKWithoutFoundKotlinVersion() {
+        val files = importProjectFromTestData()
+
+        runInEdtAndWait {
+            myTestFixture.project.executeWriteCommand("") {
+                KotlinWithGradleConfigurator.changeFeatureConfiguration(
+                    myTestFixture.module, LanguageFeature.InlineClasses, LanguageFeature.State.ENABLED, false
+                )
+            }
+
+            checkFiles(files)
+        }
+    }
+
     @TargetVersions("4.7+")
     @Test
     fun testEnableFeatureSupportToExistentArgumentsWithXFlag() = testEnableFeatureSupportToExistentArguments()
diff --git a/idea/idea-jvm/src/org/jetbrains/kotlin/cli/common/arguments/CliArgumentStringBuilder.kt b/idea/idea-jvm/src/org/jetbrains/kotlin/cli/common/arguments/CliArgumentStringBuilder.kt
index 41485cd59f6..563b7af6cfc 100644
--- a/idea/idea-jvm/src/org/jetbrains/kotlin/cli/common/arguments/CliArgumentStringBuilder.kt
+++ b/idea/idea-jvm/src/org/jetbrains/kotlin/cli/common/arguments/CliArgumentStringBuilder.kt
@@ -41,12 +41,12 @@ object CliArgumentStringBuilder {
         val dedicatedFlag = dedicatedFlagInfo?.run {
             val (xFlag, xFlagSinceVersion) = this
 
-            // TODO: replace to returning xFlag in 1.4 (behaviour for fallback)
-            if (kotlinVersion == null) return@run null
+            if (kotlinVersion == null) return@run xFlag
 
-            val isAtLeastSpecifiedVersion = versionRegex.find(kotlinVersion)?.destructured?.let { (major, minor, patch) ->
+            val parsedVersion = versionRegex.find(kotlinVersion) ?: return@run xFlag
+            val isAtLeastSpecifiedVersion = parsedVersion.destructured.let { (major, minor, patch) ->
                 KotlinVersion(major.toInt(), minor.toInt(), patch.toInt()) >= xFlagSinceVersion
-            } == true
+            }
             if (isAtLeastSpecifiedVersion) xFlag else null
         }
 
diff --git a/idea/idea-maven/testData/languageFeature/enableInlineClasses/pom.xml.after b/idea/idea-maven/testData/languageFeature/enableInlineClasses/pom.xml.after
index 8643092295f..de4556667b8 100644
--- a/idea/idea-maven/testData/languageFeature/enableInlineClasses/pom.xml.after
+++ b/idea/idea-maven/testData/languageFeature/enableInlineClasses/pom.xml.after
@@ -50,7 +50,7 @@
                 </executions>
                 <configuration>
                     <args>
-                        <arg>-XXLanguage:+InlineClasses</arg>
+                        <arg>-Xinline-classes</arg>
                     </args>
                 </configuration>
             </plugin>
diff --git a/idea/testData/gradle/configurator/enableFeatureSupportGSKWithoutFoundKotlinVersion/build.gradle.kts b/idea/testData/gradle/configurator/enableFeatureSupportGSKWithoutFoundKotlinVersion/build.gradle.kts
new file mode 100644
index 00000000000..c26e8ff7959
--- /dev/null
+++ b/idea/testData/gradle/configurator/enableFeatureSupportGSKWithoutFoundKotlinVersion/build.gradle.kts
@@ -0,0 +1,8 @@
+buildscript {
+    repositories {
+        jcenter()
+        mavenCentral()
+    }
+}
+
+apply(plugin  ="kotlin")
diff --git a/idea/testData/gradle/configurator/enableFeatureSupportGSKWithoutFoundKotlinVersion/build.gradle.kts.after b/idea/testData/gradle/configurator/enableFeatureSupportGSKWithoutFoundKotlinVersion/build.gradle.kts.after
new file mode 100644
index 00000000000..a9ec561dca5
--- /dev/null
+++ b/idea/testData/gradle/configurator/enableFeatureSupportGSKWithoutFoundKotlinVersion/build.gradle.kts.after
@@ -0,0 +1,14 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+buildscript {
+    repositories {
+        jcenter()
+        mavenCentral()
+    }
+}
+
+apply(plugin  ="kotlin")
+val compileKotlin: KotlinCompile by tasks
+compileKotlin.kotlinOptions {
+    freeCompilerArgs = listOf("-Xinline-classes")
+}
\ No newline at end of file