diff --git a/java/kotlin-extractor/build.gradle b/java/kotlin-extractor/build.gradle
new file mode 100644
index 00000000000..eb392cb5ada
--- /dev/null
+++ b/java/kotlin-extractor/build.gradle
@@ -0,0 +1,23 @@
+plugins {
+    id 'org.jetbrains.kotlin.jvm' version "${kotlinVersion}"
+    id 'org.jetbrains.dokka' version '1.4.32'
+    id "com.vanniktech.maven.publish" version '0.15.1'
+}
+
+group 'com.github.codeql'
+version '0.0.1'
+
+dependencies {
+    implementation "org.jetbrains.kotlin:kotlin-stdlib"
+    compileOnly("org.jetbrains.kotlin:kotlin-compiler")
+}
+
+repositories {
+    mavenCentral()
+}
+
+tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).configureEach {
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
diff --git a/java/kotlin-extractor/gradle.properties b/java/kotlin-extractor/gradle.properties
new file mode 100644
index 00000000000..1e999c1e9d9
--- /dev/null
+++ b/java/kotlin-extractor/gradle.properties
@@ -0,0 +1,7 @@
+kotlin.code.style=official
+kotlinVersion=1.5.21
+
+GROUP=com.github.codeql
+VERSION_NAME=0.0.1
+POM_DESCRIPTION=CodeQL Kotlin extractor
+
diff --git a/java/kotlin-extractor/settings.gradle b/java/kotlin-extractor/settings.gradle
new file mode 100644
index 00000000000..fa1b7937da6
--- /dev/null
+++ b/java/kotlin-extractor/settings.gradle
@@ -0,0 +1,8 @@
+pluginManagement {
+    repositories {
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+rootProject.name = 'codeql-kotlin-extractor'
diff --git a/java/kotlin-extractor/src/main/kotlin/KotlinExtractorCommandLineProcessor.kt b/java/kotlin-extractor/src/main/kotlin/KotlinExtractorCommandLineProcessor.kt
new file mode 100644
index 00000000000..ee7a1b6b17f
--- /dev/null
+++ b/java/kotlin-extractor/src/main/kotlin/KotlinExtractorCommandLineProcessor.kt
@@ -0,0 +1,32 @@
+package com.github.codeql
+
+import org.jetbrains.kotlin.compiler.plugin.AbstractCliOption
+import org.jetbrains.kotlin.compiler.plugin.CliOption
+import org.jetbrains.kotlin.compiler.plugin.CommandLineProcessor
+import org.jetbrains.kotlin.config.CompilerConfiguration
+import org.jetbrains.kotlin.config.CompilerConfigurationKey
+
+class KotlinExtractorCommandLineProcessor : CommandLineProcessor {
+    override val pluginId = "kotlin-extractor"
+
+    override val pluginOptions = listOf(
+        CliOption(
+            optionName = "testOption",
+            valueDescription = "A test option",
+            description = "For testing options",
+            required = false,
+            allowMultipleOccurrences = true
+        )
+    )
+
+    override fun processOption(
+        option: AbstractCliOption,
+        value: String,
+        configuration: CompilerConfiguration
+    ) = when (option.optionName) {
+        "testOption" -> configuration.appendList(KEY_TEST, value)
+        else -> error("kotlin extractor: Bad option: ${option.optionName}")
+    }
+}
+
+val KEY_TEST = CompilerConfigurationKey<List<String>>("kotlin extractor test")
diff --git a/java/kotlin-extractor/src/main/kotlin/KotlinExtractorComponentRegistrar.kt b/java/kotlin-extractor/src/main/kotlin/KotlinExtractorComponentRegistrar.kt
new file mode 100644
index 00000000000..6254f39df7e
--- /dev/null
+++ b/java/kotlin-extractor/src/main/kotlin/KotlinExtractorComponentRegistrar.kt
@@ -0,0 +1,16 @@
+package com.github.codeql
+
+import org.jetbrains.kotlin.backend.common.extensions.IrGenerationExtension
+import com.intellij.mock.MockProject
+import org.jetbrains.kotlin.compiler.plugin.ComponentRegistrar
+import org.jetbrains.kotlin.config.CompilerConfiguration
+
+class KotlinExtractorComponentRegistrar : ComponentRegistrar {
+    override fun registerProjectComponents(
+        project: MockProject,
+        configuration: CompilerConfiguration
+    ) {
+        val tests = configuration[KEY_TEST] ?: emptyList()
+        IrGenerationExtension.registerExtension(project, KotlinExtractorExtension(tests))
+    }
+}
diff --git a/java/kotlin-extractor/src/main/kotlin/KotlinExtractorExtension.kt b/java/kotlin-extractor/src/main/kotlin/KotlinExtractorExtension.kt
new file mode 100644
index 00000000000..5b0c229009a
--- /dev/null
+++ b/java/kotlin-extractor/src/main/kotlin/KotlinExtractorExtension.kt
@@ -0,0 +1,139 @@
+package com.github.codeql
+
+import java.io.BufferedWriter
+import java.io.File
+import java.nio.file.Files
+import java.nio.file.Paths
+import kotlin.system.exitProcess
+import org.jetbrains.kotlin.backend.common.extensions.IrGenerationExtension
+import org.jetbrains.kotlin.backend.common.extensions.IrPluginContext
+import org.jetbrains.kotlin.ir.IrElement
+import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrFile
+import org.jetbrains.kotlin.ir.declarations.path
+import org.jetbrains.kotlin.ir.util.dump
+import org.jetbrains.kotlin.ir.util.packageFqName
+import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
+import org.jetbrains.kotlin.ir.IrFileEntry
+
+class KotlinExtractorExtension(private val tests: List<String>) : IrGenerationExtension {
+    override fun generate(moduleFragment: IrModuleFragment, pluginContext: IrPluginContext) {
+        val trapDir = File(System.getenv("CODEQL_EXTRACTOR_KOTLIN_TRAP_DIR").takeUnless { it.isNullOrEmpty() } ?: "kotlin-extractor/trap")
+        trapDir.mkdirs()
+        val srcDir = File(System.getenv("CODEQL_EXTRACTOR_KOTLIN_SOURCE_ARCHIVE_DIR").takeUnless { it.isNullOrEmpty() } ?: "kotlin-extractor/src")
+        srcDir.mkdirs()
+        moduleFragment.accept(KotlinExtractorVisitor(trapDir, srcDir), RootTrapWriter())
+        // We don't want the compiler to continue and generate class
+        // files etc, so we just exit when we are finished extracting.
+        exitProcess(0)
+    }
+}
+
+fun extractorBug(msg: String) {
+    println(msg)
+}
+
+interface TrapWriter {
+    fun writeTrap(trap: String)
+    fun getLocation(startOffset: Int, endOffset: Int): Int
+    fun getIdFor(label: String): Int
+    fun getFreshId(): Int
+}
+
+class RootTrapWriter: TrapWriter {
+    override fun writeTrap(trap: String) {
+        extractorBug("Tried to write TRAP outside a file: $trap")
+    }
+    override fun getLocation(startOffset: Int, endOffset: Int): Int {
+        extractorBug("Asked for location, but not in a file")
+        return 0
+    }
+    override fun getIdFor(label: String): Int {
+        extractorBug("Asked for ID for '$label' outside a file")
+        return 0
+    }
+    override fun getFreshId(): Int {
+        extractorBug("Asked for fresh ID outside a file")
+        return 0
+    }
+}
+
+class FileTrapWriter(
+    val fileLabel: String,
+    val file: BufferedWriter,
+    val fileEntry: IrFileEntry
+): TrapWriter {
+    var nextId: Int = 100
+    override fun writeTrap(trap: String) {
+        file.write(trap)
+    }
+    override fun getLocation(startOffset: Int, endOffset: Int): Int {
+        val startLine = fileEntry.getLineNumber(startOffset) + 1
+        val startColumn = fileEntry.getColumnNumber(startOffset) + 1
+        val endLine = fileEntry.getLineNumber(endOffset) + 1
+        val endColumn = fileEntry.getColumnNumber(endOffset)
+        val id = getFreshId()
+        val fileId = getIdFor(fileLabel)
+        writeTrap("#$id = @\"loc,{#$fileId},$startLine,$startColumn,$endLine,$endColumn\"\n")
+        writeTrap("locations_default(#$id, #$fileId, $startLine, $startColumn, $endLine, $endColumn)\n")
+        return id
+    }
+    val labelMapping: MutableMap<String, Int> = mutableMapOf<String, Int>()
+    override fun getIdFor(label: String): Int {
+        val maybeId = labelMapping.get(label)
+        if(maybeId == null) {
+            val id = getFreshId()
+            labelMapping.put(label, id)
+            return id
+        } else {
+            return maybeId
+        }
+    }
+    override fun getFreshId(): Int {
+        return nextId++
+    }
+}
+
+class KotlinExtractorVisitor(val trapDir: File, val srcDir: File) : IrElementVisitor<Unit, TrapWriter> {
+    override fun visitElement(element: IrElement, data: TrapWriter) {
+        extractorBug("Unrecognised IrElement: " + element.javaClass)
+        if(data is RootTrapWriter) {
+            extractorBug("... and outside any file!")
+        }
+        element.acceptChildren(this, data)
+    }
+    override fun visitClass(declaration: IrClass, data: TrapWriter) {
+        val id = data.getFreshId()
+        val locId = data.getLocation(declaration.startOffset, declaration.endOffset)
+        val pkg = declaration.packageFqName?.asString() ?: ""
+        val cls = declaration.name.asString()
+        data.writeTrap("#$id = @\"class;$pkg.$cls\"\n")
+        data.writeTrap("classes(#$id, \"$cls\")\n")
+        data.writeTrap("hasLocation(#$id, #$locId)\n")
+        declaration.acceptChildren(this, data)
+    }
+    override fun visitFile(declaration: IrFile, data: TrapWriter) {
+        val filePath = declaration.path
+        val file = File(filePath)
+        val fileLabel = "@\"$filePath;sourcefile\""
+        val basename = file.nameWithoutExtension
+        val extension = file.extension
+        val dest = Paths.get("$srcDir/${declaration.path}")
+        val destDir = dest.getParent()
+        Files.createDirectories(destDir)
+        Files.copy(Paths.get(declaration.path), dest)
+
+        val trapFile = File("$trapDir/$filePath.trap")
+        val trapFileDir = trapFile.getParentFile()
+        trapFileDir.mkdirs()
+        trapFile.bufferedWriter().use { trapFileBW ->
+            val tw = FileTrapWriter(fileLabel, trapFileBW, declaration.fileEntry)
+            val id = tw.getIdFor(fileLabel)
+            tw.writeTrap("#$id = $fileLabel\n")
+            tw.writeTrap("files(#$id, \"$filePath\", \"$basename\", \"$extension\", 0)\n")
+            declaration.acceptChildren(this, tw)
+        }
+    }
+}
+
diff --git a/java/kotlin-extractor/src/main/resources/META-INF/services/org.jetbrains.kotlin.compiler.plugin.CommandLineProcessor b/java/kotlin-extractor/src/main/resources/META-INF/services/org.jetbrains.kotlin.compiler.plugin.CommandLineProcessor
new file mode 100644
index 00000000000..2d0055c74d4
--- /dev/null
+++ b/java/kotlin-extractor/src/main/resources/META-INF/services/org.jetbrains.kotlin.compiler.plugin.CommandLineProcessor
@@ -0,0 +1 @@
+com.github.codeql.KotlinExtractorCommandLineProcessor
diff --git a/java/kotlin-extractor/src/main/resources/META-INF/services/org.jetbrains.kotlin.compiler.plugin.ComponentRegistrar b/java/kotlin-extractor/src/main/resources/META-INF/services/org.jetbrains.kotlin.compiler.plugin.ComponentRegistrar
new file mode 100644
index 00000000000..564ed6bfe25
--- /dev/null
+++ b/java/kotlin-extractor/src/main/resources/META-INF/services/org.jetbrains.kotlin.compiler.plugin.ComponentRegistrar
@@ -0,0 +1 @@
+com.github.codeql.KotlinExtractorComponentRegistrar