diff --git a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TarFormat.java b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TarFormat.java
index 228de7c37..23f4beda1 100644
--- a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TarFormat.java
+++ b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TarFormat.java
@@ -44,6 +44,9 @@ package org.eclipse.jgit.archive;
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 
 import org.apache.commons.compress.archivers.ArchiveOutputStream;
 import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
@@ -57,6 +60,9 @@ import org.eclipse.jgit.lib.ObjectLoader;
  * Unix TAR format (ustar + some PAX extensions).
  */
 public class TarFormat implements ArchiveCommand.Format<ArchiveOutputStream> {
+	private static final List<String> SUFFIXES =
+			Collections.unmodifiableList(Arrays.asList(".tar"));
+
 	public ArchiveOutputStream createArchiveOutputStream(OutputStream s) {
 		TarArchiveOutputStream out = new TarArchiveOutputStream(s, "UTF-8"); //$NON-NLS-1$
 		out.setLongFileMode(TarArchiveOutputStream.LONGFILE_POSIX);
@@ -90,4 +96,8 @@ public class TarFormat implements ArchiveCommand.Format<ArchiveOutputStream> {
 		loader.copyTo(out);
 		out.closeArchiveEntry();
 	}
+
+	public Iterable<String> suffixes() {
+		return SUFFIXES;
+	}
 }
diff --git a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/Tbz2Format.java b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/Tbz2Format.java
index 9883118ea..d3482d181 100644
--- a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/Tbz2Format.java
+++ b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/Tbz2Format.java
@@ -44,6 +44,9 @@ package org.eclipse.jgit.archive;
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 
 import org.apache.commons.compress.archivers.ArchiveOutputStream;
 import org.apache.commons.compress.compressors.bzip2.BZip2CompressorOutputStream;
@@ -55,6 +58,10 @@ import org.eclipse.jgit.lib.ObjectLoader;
  * bzip2-compressed tarball (tar.bz2) format.
  */
 public class Tbz2Format implements ArchiveCommand.Format<ArchiveOutputStream> {
+	private static final List<String> SUFFIXES =
+			Collections.unmodifiableList(Arrays.asList(
+				".tar.bz2", ".tbz", ".tbz2"));
+
 	private final ArchiveCommand.Format<ArchiveOutputStream> tarFormat = new TarFormat();
 
 	public ArchiveOutputStream createArchiveOutputStream(OutputStream s)
@@ -68,4 +75,8 @@ public class Tbz2Format implements ArchiveCommand.Format<ArchiveOutputStream> {
 			throws IOException {
 		tarFormat.putEntry(out, path, mode, loader);
 	}
+
+	public Iterable<String> suffixes() {
+		return SUFFIXES;
+	}
 }
diff --git a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TgzFormat.java b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TgzFormat.java
index 1c72bf8dc..fe1350cbb 100644
--- a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TgzFormat.java
+++ b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TgzFormat.java
@@ -44,6 +44,9 @@ package org.eclipse.jgit.archive;
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 
 import org.apache.commons.compress.archivers.ArchiveOutputStream;
 import org.apache.commons.compress.compressors.gzip.GzipCompressorOutputStream;
@@ -55,6 +58,10 @@ import org.eclipse.jgit.lib.ObjectLoader;
  * gzip-compressed tarball (tar.gz) format.
  */
 public class TgzFormat implements ArchiveCommand.Format<ArchiveOutputStream> {
+	private static final List<String> SUFFIXES =
+			Collections.unmodifiableList(Arrays.asList(
+				".tar.gz", ".tgz"));
+
 	private final ArchiveCommand.Format<ArchiveOutputStream> tarFormat = new TarFormat();
 
 	public ArchiveOutputStream createArchiveOutputStream(OutputStream s)
@@ -68,4 +75,8 @@ public class TgzFormat implements ArchiveCommand.Format<ArchiveOutputStream> {
 			throws IOException {
 		tarFormat.putEntry(out, path, mode, loader);
 	}
+
+	public Iterable<String> suffixes() {
+		return SUFFIXES;
+	}
 }
diff --git a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TxzFormat.java b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TxzFormat.java
index d1547c683..c09b0621a 100644
--- a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TxzFormat.java
+++ b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/TxzFormat.java
@@ -44,6 +44,9 @@ package org.eclipse.jgit.archive;
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 
 import org.apache.commons.compress.archivers.ArchiveOutputStream;
 import org.apache.commons.compress.compressors.xz.XZCompressorOutputStream;
@@ -55,6 +58,10 @@ import org.eclipse.jgit.lib.ObjectLoader;
  * Xz-compressed tar (tar.xz) format.
  */
 public class TxzFormat implements ArchiveCommand.Format<ArchiveOutputStream> {
+	private static final List<String> SUFFIXES =
+			Collections.unmodifiableList(Arrays.asList(
+				".tar.xz", ".txz"));
+
 	private final ArchiveCommand.Format<ArchiveOutputStream> tarFormat = new TarFormat();
 
 	public ArchiveOutputStream createArchiveOutputStream(OutputStream s)
@@ -68,4 +75,8 @@ public class TxzFormat implements ArchiveCommand.Format<ArchiveOutputStream> {
 			throws IOException {
 		tarFormat.putEntry(out, path, mode, loader);
 	}
+
+	public Iterable<String> suffixes() {
+		return SUFFIXES;
+	}
 }
diff --git a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/ZipFormat.java b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/ZipFormat.java
index a0906d4dd..00c962bc9 100644
--- a/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/ZipFormat.java
+++ b/org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/ZipFormat.java
@@ -44,6 +44,9 @@ package org.eclipse.jgit.archive;
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 
 import org.apache.commons.compress.archivers.ArchiveOutputStream;
 import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
@@ -56,6 +59,9 @@ import org.eclipse.jgit.lib.ObjectLoader;
  * PKWARE's ZIP format.
  */
 public class ZipFormat implements ArchiveCommand.Format<ArchiveOutputStream> {
+	private static final List<String> SUFFIXES =
+			Collections.unmodifiableList(Arrays.asList(".zip"));
+
 	public ArchiveOutputStream createArchiveOutputStream(OutputStream s) {
 		return new ZipArchiveOutputStream(s);
 	}
@@ -79,4 +85,8 @@ public class ZipFormat implements ArchiveCommand.Format<ArchiveOutputStream> {
 		loader.copyTo(out);
 		out.closeArchiveEntry();
 	}
+
+	public Iterable<String> suffixes() {
+		return SUFFIXES;
+	}
 }
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/ArchiveCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/ArchiveCommand.java
index 7726e15ee..ab94d3a80 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/ArchiveCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/ArchiveCommand.java
@@ -46,6 +46,8 @@ import java.io.Closeable;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.text.MessageFormat;
+import java.util.Collection;
+import java.util.Iterator;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
@@ -151,6 +153,18 @@ public class ArchiveCommand extends GitCommand<OutputStream> {
 		 */
 		void putEntry(T out, String path, FileMode mode,
 				ObjectLoader loader) throws IOException;
+
+		/**
+		 * Filename suffixes representing this format (e.g.,
+		 * { ".tar.gz", ".tgz" }).
+		 *
+		 * The behavior is undefined when suffixes overlap (if
+		 * one format claims suffix ".7z", no other format should
+		 * take ".tar.7z").
+		 *
+		 * @return this format's suffixes
+		 */
+		Iterable<String> suffixes();
 	}
 
 	/**
@@ -199,6 +213,8 @@ public class ArchiveCommand extends GitCommand<OutputStream> {
 	 *              An archival format with that name was already registered.
 	 */
 	public static void registerFormat(String name, Format<?> fmt) {
+		// TODO(jrn): Check that suffixes don't overlap.
+
 		if (formats.putIfAbsent(name, fmt) != null)
 			throw new JGitInternalException(MessageFormat.format(
 					JGitText.get().archiveFormatAlreadyRegistered,
@@ -220,6 +236,16 @@ public class ArchiveCommand extends GitCommand<OutputStream> {
 					name));
 	}
 
+	private static Format<?> formatBySuffix(String filenameSuffix)
+			throws UnsupportedFormatException {
+		if (filenameSuffix != null)
+			for (Format<?> fmt : formats.values())
+				for (String sfx : fmt.suffixes())
+					if (filenameSuffix.endsWith(sfx))
+						return fmt;
+		return lookupFormat("tar");
+	}
+
 	private static Format<?> lookupFormat(String formatName) throws UnsupportedFormatException {
 		Format<?> fmt = formats.get(formatName);
 		if (fmt == null)
@@ -229,7 +255,10 @@ public class ArchiveCommand extends GitCommand<OutputStream> {
 
 	private OutputStream out;
 	private ObjectId tree;
-	private String format = "tar";
+	private String format;
+
+	/** Filename suffix, for automatically choosing a format. */
+	private String suffix;
 
 	/**
 	 * @param repo
@@ -282,7 +311,11 @@ public class ArchiveCommand extends GitCommand<OutputStream> {
 	public OutputStream call() throws GitAPIException {
 		checkCallable();
 
-		final Format<?> fmt = lookupFormat(format);
+		final Format<?> fmt;
+		if (format == null)
+			fmt = formatBySuffix(suffix);
+		else
+			fmt = lookupFormat(format);
 		return writeArchive(fmt);
 	}
 
@@ -300,6 +333,26 @@ public class ArchiveCommand extends GitCommand<OutputStream> {
 		return this;
 	}
 
+	/**
+	 * Set the intended filename for the produced archive.
+	 * Currently the only effect is to determine the default
+	 * archive format when none is specified with
+	 * {@link #setFormat(String)}.
+	 *
+	 * @param filename
+	 *		intended filename for the archive
+	 */
+	public ArchiveCommand setFilename(String filename) {
+		int slash = filename.lastIndexOf('/');
+		int dot = filename.indexOf('.', slash + 1);
+
+		if (dot == -1)
+			this.suffix = "";
+		else
+			this.suffix = filename.substring(dot);
+		return this;
+	}
+
 	/**
 	 * @param out
 	 *	      the stream to which to write the archive
@@ -312,7 +365,9 @@ public class ArchiveCommand extends GitCommand<OutputStream> {
 
 	/**
 	 * @param fmt
-	 *	      archive format (e.g., "tar" or "zip")
+	 *	      archive format (e.g., "tar" or "zip").
+	 *	      null means to choose automatically based on
+	 *	      the archive filename.
 	 * @return this
 	 */
 	public ArchiveCommand setFormat(String fmt) {