diff --git a/kotlin/internal/jvm/compile.bzl b/kotlin/internal/jvm/compile.bzl
index e94a69c4f..e22ef2e3f 100644
--- a/kotlin/internal/jvm/compile.bzl
+++ b/kotlin/internal/jvm/compile.bzl
@@ -427,6 +427,10 @@ def _run_kt_builder_action(
         omit_if_empty = True,
     )
 
+    # Post-process class files with the Jacoco offline instrumenter, if needed.
+    if ctx.coverage_instrumented():
+        args.add("--post_processor", "jacoco")
+
     args.add("--build_java", build_java)
     args.add("--build_kotlin", build_kotlin)
 
@@ -466,12 +470,14 @@ def _run_kt_builder_action(
 
 # MAIN ACTIONS #########################################################################################################
 
-def kt_jvm_produce_jar_actions(ctx, rule_kind):
+def kt_jvm_produce_jar_actions(ctx, rule_kind, transitive_files=depset(order="default"), extra_runfiles=[]):
     """This macro sets up a compile action for a Kotlin jar.
 
     Args:
         ctx: Invoking rule ctx, used for attr, actions, and label.
         rule_kind: The rule kind --e.g., `kt_jvm_library`.
+        transitive_files: Transitive files to inject into the output set.
+        extra_runfiles: Extra runfiles to append to the output set.
     Returns:
         A struct containing the providers JavaInfo (`java`) and `kt` (KtJvmInfo). This struct is not intended to be
         used as a legacy provider -- rather the caller should transform the result.
@@ -552,6 +558,19 @@ def kt_jvm_produce_jar_actions(ctx, rule_kind):
         java_toolchain = toolchains.java,
         host_javabase = toolchains.java_runtime)
 
+    outs = [output_jar]
+    if hasattr(ctx.outputs, "executable"):
+        outs.append(ctx.outputs.executable)
+
+    default_info = DefaultInfo(
+        files = depset(outs),
+        runfiles = ctx.runfiles(
+            files = extra_runfiles + [output_jar],
+            transitive_files = transitive_files,
+            collect_default = True,
+        ),
+    )
+
     return struct(
         java = JavaInfo(
             output_jar = output_jar,
@@ -778,3 +797,4 @@ def export_only_providers(ctx, actions, attr, outputs):
             ),
         ),
     )
+
diff --git a/kotlin/internal/jvm/impl.bzl b/kotlin/internal/jvm/impl.bzl
index e2a4d1362..4280eef52 100644
--- a/kotlin/internal/jvm/impl.bzl
+++ b/kotlin/internal/jvm/impl.bzl
@@ -45,6 +45,11 @@ def _make_providers(ctx, providers, transitive_files = depset(order = "default")
                 ),
             ),
         ],
+        instrumented_files = struct(
+            source_attributes = ["srcs"],
+            dependency_attributes = ["deps", "runtime_deps"],
+            extensions = ["kt", "java"],
+        ),
     )
 
 def _write_launcher_action(ctx, rjars, main_class, jvm_flags, args = "", wrapper_preamble = ""):
diff --git a/kotlin/internal/jvm/jvm.bzl b/kotlin/internal/jvm/jvm.bzl
index 46e372bd2..5963a710e 100644
--- a/kotlin/internal/jvm/jvm.bzl
+++ b/kotlin/internal/jvm/jvm.bzl
@@ -151,7 +151,7 @@ _implicit_deps = {
         default = Label("@bazel_tools//tools/jdk:JacocoCoverage"),
     ),
     "_lcov_merger": attr.label(
-        default = Label("@bazel_tools//tools/test:LcovMerger"),
+        default = Label("@bazel_tools//tools/test:lcov_merger"),
         executable = True,
         cfg = "target",
     ),
diff --git a/kotlin/internal/repositories/setup.bzl b/kotlin/internal/repositories/setup.bzl
index 756057bf3..d8fc218dd 100644
--- a/kotlin/internal/repositories/setup.bzl
+++ b/kotlin/internal/repositories/setup.bzl
@@ -39,16 +39,16 @@ def kt_configure():
             "javax.annotation:javax.annotation-api:1.3.2",
             "javax.inject:javax.inject:1",
             "org.pantsbuild:jarjar:1.7.2",
-            "org.jacoco:org.jacoco.core:0.8.6",
+            "org.jacoco:org.jacoco.core:0.8.3",
             "org.jetbrains.kotlinx:atomicfu-js:0.14.0",
             "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.9",
             "org.jetbrains.kotlinx:kotlinx-coroutines-core-js:1.3.9",
             "org.jetbrains.kotlinx:kotlinx-coroutines-test:1.3.9",
             "org.jetbrains.kotlinx:kotlinx-coroutines-debug:1.3.9",
             "org.jetbrains.kotlinx:kotlinx-serialization-runtime:1.0-M1-1.4.0-rc",
-            "org.ow2.asm:asm-commons:6.0",
-            "org.ow2.asm:asm-tree:6.0",
-            "org.ow2.asm:asm:6.0",
+            "org.ow2.asm:asm-commons:9.0",
+            "org.ow2.asm:asm-tree:9.0",
+            "org.ow2.asm:asm:9.0",
         ],
         repositories = [
             "https://maven-central.storage.googleapis.com/repos/central/data/",
diff --git a/src/main/kotlin/BUILD b/src/main/kotlin/BUILD
index b9d5be448..e1d9b027c 100644
--- a/src/main/kotlin/BUILD
+++ b/src/main/kotlin/BUILD
@@ -52,7 +52,12 @@ java_binary(
     ],
     main_class = "io.bazel.kotlin.builder.KotlinBuilderMain",
     visibility = ["//visibility:public"],
-    runtime_deps = [":builder_jar_jar"],
+    runtime_deps = [
+        ":builder_jar_jar",
+        "@kotlin_rules_maven//:org_ow2_asm_asm",
+        "@kotlin_rules_maven//:org_ow2_asm_asm_commons",
+        "@kotlin_rules_maven//:org_ow2_asm_asm_tree",
+    ],
 )
 
 java_binary(
diff --git a/src/main/kotlin/io/bazel/kotlin/builder/tasks/BUILD.bazel b/src/main/kotlin/io/bazel/kotlin/builder/tasks/BUILD.bazel
index b07e40672..349becacc 100644
--- a/src/main/kotlin/io/bazel/kotlin/builder/tasks/BUILD.bazel
+++ b/src/main/kotlin/io/bazel/kotlin/builder/tasks/BUILD.bazel
@@ -29,6 +29,7 @@ kt_bootstrap_library(
         "@com_github_jetbrains_kotlin//:kotlin-preloader",
         "@kotlin_rules_maven//:com_google_protobuf_protobuf_java",
         "@kotlin_rules_maven//:com_google_protobuf_protobuf_java_util",
+        "@kotlin_rules_maven//:org_jacoco_org_jacoco_core",
         "@kotlin_rules_maven//:javax_inject_javax_inject",
     ],
 )
diff --git a/src/main/kotlin/io/bazel/kotlin/builder/tasks/KotlinBuilder.kt b/src/main/kotlin/io/bazel/kotlin/builder/tasks/KotlinBuilder.kt
index da2b07898..9a94611e9 100644
--- a/src/main/kotlin/io/bazel/kotlin/builder/tasks/KotlinBuilder.kt
+++ b/src/main/kotlin/io/bazel/kotlin/builder/tasks/KotlinBuilder.kt
@@ -98,6 +98,7 @@ class KotlinBuilder @Inject internal constructor(
 
     enum class KotlinBuilderFlags(override val flag: String) : Flag {
       MODULE_NAME("--kotlin_module_name"),
+      POST_PROCESSOR("--post_processor"),
       PASSTHROUGH_FLAGS("--kotlin_passthrough_flags"),
       API_VERSION("--kotlin_api_version"),
       LANGUAGE_VERSION("--kotlin_language_version"),
@@ -175,6 +176,8 @@ class KotlinBuilder @Inject internal constructor(
       }
       addAllPassthroughFlags(argMap.optional(KotlinBuilderFlags.PASSTHROUGH_FLAGS) ?: emptyList())
 
+      argMap.optionalSingle(KotlinBuilderFlags.POST_PROCESSOR)?.let(::setPostProcessor)
+
       argMap.optional(KotlinBuilderFlags.FRIEND_PATHS)?.let(::addAllFriendPaths)
       toolchainInfoBuilder.commonBuilder.apiVersion =
         argMap.mandatorySingle(KotlinBuilderFlags.API_VERSION)
diff --git a/src/main/kotlin/io/bazel/kotlin/builder/tasks/jvm/JacocoProcessor.kt b/src/main/kotlin/io/bazel/kotlin/builder/tasks/jvm/JacocoProcessor.kt
new file mode 100644
index 000000000..7d2fcb01f
--- /dev/null
+++ b/src/main/kotlin/io/bazel/kotlin/builder/tasks/jvm/JacocoProcessor.kt
@@ -0,0 +1,47 @@
+package io.bazel.kotlin.builder.tasks.jvm
+
+import io.bazel.kotlin.builder.toolchain.KotlinToolchain
+import org.jacoco.core.instr.Instrumenter
+import org.jacoco.core.runtime.OfflineInstrumentationAccessGenerator
+import java.io.BufferedInputStream
+import java.io.BufferedOutputStream
+import java.io.IOException
+import java.nio.file.FileVisitResult
+import java.nio.file.Files
+import java.nio.file.Path
+import java.nio.file.Paths
+import java.nio.file.SimpleFileVisitor
+import java.nio.file.attribute.BasicFileAttributes
+import io.bazel.kotlin.model.JvmCompilationTask
+import com.google.devtools.build.lib.view.proto.Deps
+import javax.inject.Inject
+
+
+/** Implements Jacoco instrumentation. */
+class JacocoProcessor @Inject constructor(val compiler: KotlinToolchain.KotlincInvoker) {
+    fun instrument(command: JvmCompilationTask) {
+        val classDir = Paths.get(command.directories.classes)
+        val instr = Instrumenter(OfflineInstrumentationAccessGenerator())
+
+        // Runs Jacoco instrumentation processor over all .class files.
+        Files.walkFileTree(
+            classDir,
+            object : SimpleFileVisitor<Path>() {
+                override fun visitFile(file: Path, attrs: BasicFileAttributes): FileVisitResult {
+                    if (!file.fileName.toString().endsWith(".class")) {
+                        return FileVisitResult.CONTINUE
+                    }
+
+                    val uninstrumentedCopy = Paths.get(file.toString() + ".uninstrumented")
+                    Files.move(file, uninstrumentedCopy)
+                    BufferedInputStream(Files.newInputStream(uninstrumentedCopy)).use { input ->
+                        BufferedOutputStream(Files.newOutputStream(file)).use { output ->
+                            instr.instrument(input, output, file.toString())
+                        }
+                    }
+                    return FileVisitResult.CONTINUE
+                }
+            })
+    }
+}
+
diff --git a/src/main/kotlin/io/bazel/kotlin/builder/tasks/jvm/KotlinJvmTaskExecutor.kt b/src/main/kotlin/io/bazel/kotlin/builder/tasks/jvm/KotlinJvmTaskExecutor.kt
index ef88fe269..817fb188c 100644
--- a/src/main/kotlin/io/bazel/kotlin/builder/tasks/jvm/KotlinJvmTaskExecutor.kt
+++ b/src/main/kotlin/io/bazel/kotlin/builder/tasks/jvm/KotlinJvmTaskExecutor.kt
@@ -34,7 +34,8 @@ class KotlinJvmTaskExecutor @Inject internal constructor(
   private val compiler: KotlinToolchain.KotlincInvoker,
   private val javaCompiler: JavaCompiler,
   private val jDepsGenerator: JDepsGenerator,
-  private val plugins: InternalCompilerPlugins
+  private val plugins: InternalCompilerPlugins,
+  private val jacocoProcessor: JacocoProcessor
 ) {
 
   private fun combine(one: Throwable?, two: Throwable?): Throwable? {
@@ -105,6 +106,11 @@ class KotlinJvmTaskExecutor @Inject internal constructor(
           }
         }
 
+        if (this.info.postProcessor == "jacoco") {
+          context.execute("instrument class files") {
+            jacocoProcessor.instrument(this)
+          }
+        }
         if (outputs.jar.isNotEmpty()) {
           context.execute("create jar", ::createOutputJar)
         }
diff --git a/src/main/protobuf/kotlin_model.proto b/src/main/protobuf/kotlin_model.proto
index 0224f65c9..21bf1aaa1 100644
--- a/src/main/protobuf/kotlin_model.proto
+++ b/src/main/protobuf/kotlin_model.proto
@@ -78,6 +78,8 @@ message CompilationTaskInfo {
     // trace: enables trace logging.
     // timings: causes timing information to be printed at the of an action.
     repeated string debug = 9;
+    // Named post-processor to apply, if any.
+    string post_processor = 10;
 }
 
 // Mested messages not marked with stable could be refactored.