diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectReader.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectReader.java
index 68fee612f..42851498b 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectReader.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectReader.java
@@ -436,6 +436,19 @@ public abstract class ObjectReader {
 		// Do nothing by default, most readers don't want or need advice.
 	}
 
+	/**
+	 * Advise the reader to avoid unreachable objects.
+	 * <p>
+	 * While enabled the reader will skip over anything previously proven to be
+	 * unreachable. This may be dangerous in the face of concurrent writes.
+	 *
+	 * @param avoid
+	 *            true to avoid unreachable objects.
+	 */
+	public void setAvoidUnreachableObjects(boolean avoid) {
+		// Do nothing by default.
+	}
+
 	/**
 	 * An index that can be used to speed up ObjectWalks.
 	 *
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsPackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsPackFile.java
index 80cced84e..707488b03 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsPackFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsPackFile.java
@@ -45,9 +45,10 @@
 
 package org.eclipse.jgit.storage.dfs;
 
+import static org.eclipse.jgit.storage.dfs.DfsObjDatabase.PackSource.UNREACHABLE_GARBAGE;
 import static org.eclipse.jgit.storage.pack.PackExt.BITMAP_INDEX;
-import static org.eclipse.jgit.storage.pack.PackExt.PACK;
 import static org.eclipse.jgit.storage.pack.PackExt.INDEX;
+import static org.eclipse.jgit.storage.pack.PackExt.PACK;
 
 import java.io.BufferedInputStream;
 import java.io.EOFException;
@@ -276,8 +277,12 @@ public final class DfsPackFile {
 		}
 	}
 
+	final boolean isGarbage() {
+		return packDesc.getPackSource() == UNREACHABLE_GARBAGE;
+	}
+
 	PackBitmapIndex getBitmapIndex(DfsReader ctx) throws IOException {
-		if (invalid)
+		if (invalid || isGarbage())
 			return null;
 		DfsBlockCache.Ref<PackBitmapIndex> idxref = bitmapIndex;
 		if (idxref != null) {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsReader.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsReader.java
index 7d5fb5b2a..401c483d4 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsReader.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsReader.java
@@ -118,6 +118,8 @@ public final class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 
 	private boolean wantReadAhead;
 
+	private boolean avoidUnreachable;
+
 	private List<ReadAheadTask.BlockFuture> pendingReadAhead;
 
 	DfsReader(DfsObjDatabase db) {
@@ -143,6 +145,11 @@ public final class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 		return new DfsReader(db);
 	}
 
+	@Override
+	public void setAvoidUnreachableObjects(boolean avoid) {
+		avoidUnreachable = avoid;
+	}
+
 	@Override
 	public BitmapIndex getBitmapIndex() throws IOException {
 		for (DfsPackFile pack : db.getPacks()) {
@@ -169,8 +176,11 @@ public final class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 			throws IOException {
 		if (id.isComplete())
 			return Collections.singleton(id.toObjectId());
+		boolean noGarbage = avoidUnreachable;
 		HashSet<ObjectId> matches = new HashSet<ObjectId>(4);
 		for (DfsPackFile pack : db.getPacks()) {
+			if (noGarbage && pack.isGarbage())
+				continue;
 			pack.resolve(this, matches, id, 256);
 			if (256 <= matches.size())
 				break;
@@ -182,8 +192,9 @@ public final class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 	public boolean has(AnyObjectId objectId) throws IOException {
 		if (last != null && last.hasObject(this, objectId))
 			return true;
+		boolean noGarbage = avoidUnreachable;
 		for (DfsPackFile pack : db.getPacks()) {
-			if (last == pack)
+			if (pack == last || (noGarbage && pack.isGarbage()))
 				continue;
 			if (pack.hasObject(this, objectId)) {
 				last = pack;
@@ -203,8 +214,9 @@ public final class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 				return ldr;
 		}
 
+		boolean noGarbage = avoidUnreachable;
 		for (DfsPackFile pack : db.getPacks()) {
-			if (pack == last)
+			if (pack == last || (noGarbage && pack.isGarbage()))
 				continue;
 			ObjectLoader ldr = pack.get(this, objectId);
 			if (ldr != null) {
@@ -265,6 +277,7 @@ public final class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 
 		int lastIdx = 0;
 		DfsPackFile lastPack = packList[lastIdx];
+		boolean noGarbage = avoidUnreachable;
 
 		OBJECT_SCAN: for (T t : objectIds) {
 			try {
@@ -281,6 +294,8 @@ public final class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 				if (i == lastIdx)
 					continue;
 				DfsPackFile pack = packList[i];
+				if (noGarbage && pack.isGarbage())
+					continue;
 				try {
 					long p = pack.findOffset(this, t);
 					if (0 < p) {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
index f0ba0cdc5..12f688658 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
@@ -792,6 +792,7 @@ public class UploadPack {
 
 		sentReady = false;
 		int haveCnt = 0;
+		walk.getObjectReader().setAvoidUnreachableObjects(true);
 		AsyncRevObjectQueue q = walk.parseAny(peerHas, false);
 		try {
 			for (;;) {
@@ -838,6 +839,7 @@ public class UploadPack {
 			}
 		} finally {
 			q.release();
+			walk.getObjectReader().setAvoidUnreachableObjects(false);
 		}
 
 		int missCnt = peerHas.size() - haveCnt;