diff --git a/cmd/zipsync/Android.bp b/cmd/zipsync/Android.bp
new file mode 100644
index 0000000..22feadc
--- /dev/null
+++ b/cmd/zipsync/Android.bp
@@ -0,0 +1,25 @@
+// Copyright 2016 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+blueprint_go_binary {
+    name: "zipsync",
+    deps: [
+        "android-archive-zip",
+        "blueprint-pathtools",
+    ],
+    srcs: [
+        "zipsync.go",
+    ],
+}
+
diff --git a/cmd/zipsync/zipsync.go b/cmd/zipsync/zipsync.go
new file mode 100644
index 0000000..035a145
--- /dev/null
+++ b/cmd/zipsync/zipsync.go
@@ -0,0 +1,124 @@
+// Copyright 2018 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"archive/zip"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+var (
+	outputDir  = flag.String("d", "", "output dir")
+	outputFile = flag.String("l", "", "output list file")
+	filter     = flag.String("f", "", "optional filter pattern")
+)
+
+func must(err error) {
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func writeFile(filename string, in io.Reader, perm os.FileMode) error {
+	out, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
+	if err != nil {
+		return err
+	}
+	_, err = io.Copy(out, in)
+	if err != nil {
+		out.Close()
+		return err
+	}
+
+	return out.Close()
+}
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintln(os.Stderr, "usage: zipsync -d <output dir> [-l <output file>] [-f <pattern>] [zip]...")
+		flag.PrintDefaults()
+	}
+
+	flag.Parse()
+
+	if *outputDir == "" {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	inputs := flag.Args()
+
+	// For now, just wipe the output directory and replace its contents with the zip files
+	// Eventually this could only modify the directory contents as necessary to bring it up
+	// to date with the zip files.
+	must(os.RemoveAll(*outputDir))
+
+	must(os.MkdirAll(*outputDir, 0777))
+
+	var files []string
+	seen := make(map[string]string)
+
+	for _, input := range inputs {
+		reader, err := zip.OpenReader(input)
+		if err != nil {
+			log.Fatal(err)
+		}
+		defer reader.Close()
+
+		for _, f := range reader.File {
+			if *filter != "" {
+				if match, err := filepath.Match(*filter, filepath.Base(f.Name)); err != nil {
+					log.Fatal(err)
+				} else if !match {
+					continue
+				}
+			}
+			if filepath.IsAbs(f.Name) {
+				log.Fatal("%q in %q is an absolute path", f.Name, input)
+			}
+
+			if prev, exists := seen[f.Name]; exists {
+				log.Fatal("%q found in both %q and %q", f.Name, prev, input)
+			}
+			seen[f.Name] = input
+
+			filename := filepath.Join(*outputDir, f.Name)
+			if f.FileInfo().IsDir() {
+				must(os.MkdirAll(filename, f.FileInfo().Mode()))
+			} else {
+				must(os.MkdirAll(filepath.Dir(filename), 0777))
+				in, err := f.Open()
+				if err != nil {
+					log.Fatal(err)
+				}
+				must(writeFile(filename, in, f.FileInfo().Mode()))
+				in.Close()
+				files = append(files, filename)
+			}
+		}
+	}
+
+	if *outputFile != "" {
+		data := strings.Join(files, "\n") + "\n"
+		must(ioutil.WriteFile(*outputFile, []byte(data), 0666))
+	}
+}
diff --git a/java/builder.go b/java/builder.go
index ee0d8a8..12110f2 100644
--- a/java/builder.go
+++ b/java/builder.go
@@ -41,7 +41,7 @@
 	javac = pctx.AndroidGomaStaticRule("javac",
 		blueprint.RuleParams{
 			Command: `rm -rf "$outDir" "$annoDir" "$srcJarDir" && mkdir -p "$outDir" "$annoDir" "$srcJarDir" && ` +
-				`${config.ExtractSrcJarsCmd} $srcJarDir $srcJarDir/list $srcJars && ` +
+				`${config.ZipSyncCmd} -d $srcJarDir -l $srcJarDir/list -f "*.java" $srcJars && ` +
 				`${config.SoongJavacWrapper} ${config.JavacWrapper}${config.JavacCmd} ${config.JavacHeapFlags} ${config.CommonJdkFlags} ` +
 				`$javacFlags $bootClasspath $classpath ` +
 				`-source $javaVersion -target $javaVersion ` +
@@ -50,7 +50,7 @@
 			CommandDeps: []string{
 				"${config.JavacCmd}",
 				"${config.SoongZipCmd}",
-				"${config.ExtractSrcJarsCmd}",
+				"${config.ZipSyncCmd}",
 			},
 			CommandOrderOnly: []string{"${config.SoongJavacWrapper}"},
 			Rspfile:          "$out.rsp",
@@ -62,7 +62,7 @@
 	kotlinc = pctx.AndroidGomaStaticRule("kotlinc",
 		blueprint.RuleParams{
 			Command: `rm -rf "$outDir" "$srcJarDir" && mkdir -p "$outDir" "$srcJarDir" && ` +
-				`${config.ExtractSrcJarsCmd} $srcJarDir $srcJarDir/list $srcJars && ` +
+				`${config.ZipSyncCmd} -d $srcJarDir -l $srcJarDir/list -f "*.java" $srcJars && ` +
 				`${config.GenKotlinBuildFileCmd} $classpath $outDir $out.rsp $srcJarDir/list > $outDir/kotlinc-build.xml &&` +
 				`${config.KotlincCmd} $kotlincFlags ` +
 				`-jvm-target $kotlinJvmTarget -Xbuild-file=$outDir/kotlinc-build.xml && ` +
@@ -72,7 +72,7 @@
 				"${config.KotlinCompilerJar}",
 				"${config.GenKotlinBuildFileCmd}",
 				"${config.SoongZipCmd}",
-				"${config.ExtractSrcJarsCmd}",
+				"${config.ZipSyncCmd}",
 			},
 			Rspfile:        "$out.rsp",
 			RspfileContent: `$in`,
@@ -82,7 +82,7 @@
 	errorprone = pctx.AndroidStaticRule("errorprone",
 		blueprint.RuleParams{
 			Command: `rm -rf "$outDir" "$annoDir" "$srcJarDir" && mkdir -p "$outDir" "$annoDir" "$srcJarDir" && ` +
-				`${config.ExtractSrcJarsCmd} $srcJarDir $srcJarDir/list $srcJars && ` +
+				`${config.ZipSyncCmd} -d $srcJarDir -l $srcJarDir/list -f "*.java" $srcJars && ` +
 				`${config.SoongJavacWrapper} ${config.ErrorProneCmd} ` +
 				`$javacFlags $bootClasspath $classpath ` +
 				`-source $javaVersion -target $javaVersion ` +
@@ -93,7 +93,7 @@
 				"${config.ErrorProneJavacJar}",
 				"${config.ErrorProneJar}",
 				"${config.SoongZipCmd}",
-				"${config.ExtractSrcJarsCmd}",
+				"${config.ZipSyncCmd}",
 			},
 			CommandOrderOnly: []string{"${config.SoongJavacWrapper}"},
 			Rspfile:          "$out.rsp",
diff --git a/java/config/config.go b/java/config/config.go
index fc2444f..3d7f910 100644
--- a/java/config/config.go
+++ b/java/config/config.go
@@ -82,13 +82,13 @@
 	pctx.SourcePathVariable("JrtFsJar", "${JavaHome}/lib/jrt-fs.jar")
 	pctx.SourcePathVariable("Ziptime", "prebuilts/build-tools/${hostPrebuiltTag}/bin/ziptime")
 
-	pctx.SourcePathVariable("ExtractSrcJarsCmd", "build/soong/scripts/extract-srcjars.sh")
 	pctx.SourcePathVariable("GenKotlinBuildFileCmd", "build/soong/scripts/gen-kotlin-build-file.sh")
 
 	pctx.SourcePathVariable("JarArgsCmd", "build/soong/scripts/jar-args.sh")
 	pctx.HostBinToolVariable("SoongZipCmd", "soong_zip")
 	pctx.HostBinToolVariable("MergeZipsCmd", "merge_zips")
 	pctx.HostBinToolVariable("Zip2ZipCmd", "zip2zip")
+	pctx.HostBinToolVariable("ZipSyncCmd", "zipsync")
 	pctx.VariableFunc("DxCmd", func(ctx android.PackageVarContext) string {
 		config := ctx.Config()
 		if config.IsEnvFalse("USE_D8") {
diff --git a/java/config/makevars.go b/java/config/makevars.go
index 7e125d5..5210f20 100644
--- a/java/config/makevars.go
+++ b/java/config/makevars.go
@@ -73,7 +73,7 @@
 	}
 
 	ctx.Strict("SOONG_JAVAC_WRAPPER", "${SoongJavacWrapper}")
-	ctx.Strict("EXTRACT_SRCJARS", "${ExtractSrcJarsCmd}")
+	ctx.Strict("ZIPSYNC", "${ZipSyncCmd}")
 
 	ctx.Strict("JACOCO_CLI_JAR", "${JacocoCLIJar}")
 	ctx.Strict("DEFAULT_JACOCO_EXCLUDE_FILTER", strings.Join(DefaultJacocoExcludeFilter, ","))
diff --git a/java/droiddoc.go b/java/droiddoc.go
index 8c60535..9a86ab5 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -28,14 +28,14 @@
 	javadoc = pctx.AndroidStaticRule("javadoc",
 		blueprint.RuleParams{
 			Command: `rm -rf "$outDir" "$srcJarDir" "$stubsDir" && mkdir -p "$outDir" "$srcJarDir" "$stubsDir" && ` +
-				`${config.ExtractSrcJarsCmd} $srcJarDir $srcJarDir/list $srcJars && ` +
+				`${config.ZipSyncCmd} -d $srcJarDir -l $srcJarDir/list -f "*.java" $srcJars && ` +
 				`${config.JavadocCmd} -encoding UTF-8 @$out.rsp @$srcJarDir/list ` +
 				`$opts $bootclasspathArgs $classpathArgs -sourcepath $sourcepath ` +
 				`-d $outDir -quiet  && ` +
 				`${config.SoongZipCmd} -write_if_changed -d -o $docZip -C $outDir -D $outDir && ` +
 				`${config.SoongZipCmd} -write_if_changed -jar -o $out -C $stubsDir -D $stubsDir`,
 			CommandDeps: []string{
-				"${config.ExtractSrcJarsCmd}",
+				"${config.ZipSyncCmd}",
 				"${config.JavadocCmd}",
 				"${config.SoongZipCmd}",
 				"$JsilverJar",
diff --git a/scripts/extract-srcjars.sh b/scripts/extract-srcjars.sh
deleted file mode 100755
index f81032b..0000000
--- a/scripts/extract-srcjars.sh
+++ /dev/null
@@ -1,44 +0,0 @@
-#!/bin/bash -e
-
-# Copyright 2017 Google Inc. All rights reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-# Extracts .java files from source jars in a specified directory and writes out a list of the files
-
-if [ -z "$1" -o -z "$2" ]; then
-  echo "usage: $0 <output dir> <output file> [<jar> ...]" >&2
-  exit 1
-fi
-
-output_dir=$1
-shift
-output_file=$1
-shift
-
-rm -f $output_file
-touch $output_file
-
-for j in "$@"; do
-  for f in $(zipinfo -1 $j '*.java'); do
-    echo $output_dir/$f >> $output_file
-  done
-  unzip -qn -d $output_dir $j '*.java'
-done
-
-duplicates=$(cat $output_file | sort | uniq -d | uniq)
-if [ -n "$duplicates" ]; then
-  echo Duplicate source files:
-  echo $duplicates
-  exit 1
-fi