diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparer.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparer.java
index ed1da4f30..d54ec996c 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparer.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriterBitmapPreparer.java
@@ -44,6 +44,7 @@
 package org.eclipse.jgit.internal.storage.pack;
 
 import static org.eclipse.jgit.internal.storage.file.PackBitmapIndex.FLAG_REUSE;
+import static org.eclipse.jgit.revwalk.RevFlag.SEEN;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -72,6 +73,7 @@
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevObject;
 import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.revwalk.filter.RevFilter;
 import org.eclipse.jgit.storage.pack.PackConfig;
 import org.eclipse.jgit.util.BlockList;
 import org.eclipse.jgit.util.SystemReader;
@@ -312,6 +314,45 @@ private boolean isRecentCommit(RevCommit revCommit) {
 		return revCommit.getCommitTime() > inactiveBranchTimestamp;
 	}
 
+	/**
+	 * A RevFilter that excludes the commits named in a bitmap from the walk.
+	 * <p>
+	 * If a commit is in {@code bitmap} then that commit is not emitted by the
+	 * walk and its parents are marked as SEEN so the walk can skip them.  The
+	 * bitmaps passed in have the property that the parents of any commit in
+	 * {@code bitmap} are also in {@code bitmap}, so marking the parents as
+	 * SEEN speeds up the RevWalk by saving it from walking down blind alleys
+	 * and does not change the commits emitted.
+	 */
+	private static class NotInBitmapFilter extends RevFilter {
+		private final BitmapBuilder bitmap;
+
+		NotInBitmapFilter(BitmapBuilder bitmap) {
+			this.bitmap = bitmap;
+		}
+
+		@Override
+		public final boolean include(RevWalk rw, RevCommit c) {
+			if (!bitmap.contains(c)) {
+				return true;
+			}
+			for (RevCommit p : c.getParents()) {
+				p.add(SEEN);
+			}
+			return false;
+		}
+
+		@Override
+		public final NotInBitmapFilter clone() {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		public final boolean requiresCommitBody() {
+			return false;
+		}
+	}
+
 	/**
 	 * For each of the {@code want}s, which represent the tip commit of each
 	 * branch, set up an initial {@link BitmapBuilder}. Reuse previously built
@@ -380,6 +421,7 @@ private CommitSelectionHelper setupTipCommitBitmaps(RevWalk rw,
 		// Create a list of commits in reverse order (older to newer).
 		// For each branch that contains the commit, mark its parents as being
 		// in the bitmap.
+		rw.setRevFilter(new NotInBitmapFilter(reuse));
 		RevCommit[] commits = new RevCommit[expectedCommitCount];
 		int pos = commits.length;
 		RevCommit rc;