diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index 8479a8e..c0f195d 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -979,6 +979,11 @@
 Caches parsed `rules.pl` contents for each project. This cache uses the same
 size as the `projects` cache, and cannot be configured independently.
 
+cache `"pure_revert"`::
++
+Result of checking if one change or commit is a pure/clean revert of
+another.
+
 cache `"sshkeys"`::
 +
 Caches unpacked versions of user SSH keys, so the internal SSH daemon
diff --git a/java/com/google/gerrit/pgm/util/BatchProgramModule.java b/java/com/google/gerrit/pgm/util/BatchProgramModule.java
index b700835..956ec75 100644
--- a/java/com/google/gerrit/pgm/util/BatchProgramModule.java
+++ b/java/com/google/gerrit/pgm/util/BatchProgramModule.java
@@ -58,6 +58,7 @@
 import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
 import com.google.gerrit.server.extensions.events.RevisionCreated;
 import com.google.gerrit.server.git.MergeUtil;
+import com.google.gerrit.server.git.PureRevertCache;
 import com.google.gerrit.server.git.SearchingChangeCacheImpl;
 import com.google.gerrit.server.git.TagCache;
 import com.google.gerrit.server.mail.send.ReplacePatchSetSender;
@@ -160,6 +161,7 @@
     install(ChangeKindCacheImpl.module());
     install(MergeabilityCacheImpl.module());
     install(TagCache.module());
+    install(PureRevertCache.module());
     factory(CapabilityCollection.Factory.class);
     factory(ChangeData.AssistedFactory.class);
     factory(ProjectState.Factory.class);
diff --git a/java/com/google/gerrit/server/cache/serialize/ProtobufSerializer.java b/java/com/google/gerrit/server/cache/serialize/ProtobufSerializer.java
new file mode 100644
index 0000000..180646b
--- /dev/null
+++ b/java/com/google/gerrit/server/cache/serialize/ProtobufSerializer.java
@@ -0,0 +1,38 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// 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 com.google.gerrit.server.cache.serialize;
+
+import com.google.gerrit.proto.Protos;
+import com.google.protobuf.MessageLite;
+import com.google.protobuf.Parser;
+
+/** A CacheSerializer for Protobuf messages. */
+public class ProtobufSerializer<T extends MessageLite> implements CacheSerializer<T> {
+  private final Parser<T> parser;
+
+  public ProtobufSerializer(Parser<T> parser) {
+    this.parser = parser;
+  }
+
+  @Override
+  public byte[] serialize(T object) {
+    return Protos.toByteArray(object);
+  }
+
+  @Override
+  public T deserialize(byte[] in) {
+    return Protos.parseUnchecked(parser, in);
+  }
+}
diff --git a/java/com/google/gerrit/server/change/PureRevert.java b/java/com/google/gerrit/server/change/PureRevert.java
index 0135683..e7fb67a 100644
--- a/java/com/google/gerrit/server/change/PureRevert.java
+++ b/java/com/google/gerrit/server/change/PureRevert.java
@@ -14,109 +14,49 @@
 
 package com.google.gerrit.server.change;
 
-import com.google.gerrit.common.Nullable;
-import com.google.gerrit.extensions.common.PureRevertInfo;
 import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
 import com.google.gerrit.reviewdb.client.PatchSet;
-import com.google.gerrit.server.PatchSetUtil;
-import com.google.gerrit.server.git.GitRepositoryManager;
-import com.google.gerrit.server.git.MergeUtil;
+import com.google.gerrit.server.git.PureRevertCache;
 import com.google.gerrit.server.notedb.ChangeNotes;
-import com.google.gerrit.server.project.ProjectCache;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.util.List;
-import org.eclipse.jgit.diff.DiffEntry;
-import org.eclipse.jgit.diff.DiffFormatter;
+import java.util.Optional;
 import org.eclipse.jgit.errors.InvalidObjectIdException;
-import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.lib.ObjectId;
-import org.eclipse.jgit.lib.ObjectInserter;
-import org.eclipse.jgit.lib.Repository;
-import org.eclipse.jgit.merge.ThreeWayMerger;
-import org.eclipse.jgit.revwalk.RevCommit;
-import org.eclipse.jgit.revwalk.RevWalk;
 
+/** Can check if a change is a pure revert (= a revert with no further modifications). */
 @Singleton
 public class PureRevert {
-  private final MergeUtil.Factory mergeUtilFactory;
-  private final GitRepositoryManager repoManager;
-  private final ProjectCache projectCache;
-  private final ChangeNotes.Factory notesFactory;
-  private final PatchSetUtil psUtil;
+  private final PureRevertCache pureRevertCache;
 
   @Inject
-  PureRevert(
-      MergeUtil.Factory mergeUtilFactory,
-      GitRepositoryManager repoManager,
-      ProjectCache projectCache,
-      ChangeNotes.Factory notesFactory,
-      PatchSetUtil psUtil) {
-    this.mergeUtilFactory = mergeUtilFactory;
-    this.repoManager = repoManager;
-    this.projectCache = projectCache;
-    this.notesFactory = notesFactory;
-    this.psUtil = psUtil;
+  PureRevert(PureRevertCache pureRevertCache) {
+    this.pureRevertCache = pureRevertCache;
   }
 
-  public PureRevertInfo get(ChangeNotes notes, @Nullable String claimedOriginal)
+  public boolean get(ChangeNotes notes, Optional<String> claimedOriginal)
       throws OrmException, IOException, BadRequestException, ResourceConflictException {
-    PatchSet currentPatchSet = psUtil.current(notes);
+    PatchSet currentPatchSet = notes.getCurrentPatchSet();
     if (currentPatchSet == null) {
       throw new ResourceConflictException("current revision is missing");
     }
-
-    if (claimedOriginal == null) {
-      if (notes.getChange().getRevertOf() == null) {
-        throw new BadRequestException("no ID was provided and change isn't a revert");
-      }
-      PatchSet ps =
-          psUtil.current(
-              notesFactory.createChecked(notes.getProjectName(), notes.getChange().getRevertOf()));
-      claimedOriginal = ps.getRevision().get();
+    if (!claimedOriginal.isPresent()) {
+      return pureRevertCache.isPureRevert(notes);
     }
 
-    try (Repository repo = repoManager.openRepository(notes.getProjectName());
-        ObjectInserter oi = repo.newObjectInserter();
-        RevWalk rw = new RevWalk(repo)) {
-      RevCommit claimedOriginalCommit;
-      try {
-        claimedOriginalCommit = rw.parseCommit(ObjectId.fromString(claimedOriginal));
-      } catch (InvalidObjectIdException | MissingObjectException e) {
-        throw new BadRequestException("invalid object ID");
-      }
-      if (claimedOriginalCommit.getParentCount() == 0) {
-        throw new BadRequestException("can't check against initial commit");
-      }
-      RevCommit claimedRevertCommit =
-          rw.parseCommit(ObjectId.fromString(currentPatchSet.getRevision().get()));
-      if (claimedRevertCommit.getParentCount() == 0) {
-        throw new BadRequestException("claimed revert has no parents");
-      }
-      // Rebase claimed revert onto claimed original
-      ThreeWayMerger merger =
-          mergeUtilFactory
-              .create(projectCache.checkedGet(notes.getProjectName()))
-              .newThreeWayMerger(oi, repo.getConfig());
-      merger.setBase(claimedRevertCommit.getParent(0));
-      boolean success = merger.merge(claimedRevertCommit, claimedOriginalCommit);
-      if (!success || merger.getResultTreeId() == null) {
-        // Merge conflict during rebase
-        return new PureRevertInfo(false);
-      }
-
-      // Any differences between claimed original's parent and the rebase result indicate that the
-      // claimedRevert is not a pure revert but made content changes
-      try (DiffFormatter df = new DiffFormatter(new ByteArrayOutputStream())) {
-        df.setReader(oi.newReader(), repo.getConfig());
-        List<DiffEntry> entries =
-            df.scan(claimedOriginalCommit.getParent(0), merger.getResultTreeId());
-        return new PureRevertInfo(entries.isEmpty());
-      }
+    ObjectId claimedOriginalObjectId;
+    try {
+      claimedOriginalObjectId = ObjectId.fromString(claimedOriginal.get());
+    } catch (InvalidObjectIdException e) {
+      throw new BadRequestException("invalid object ID");
     }
+
+    return pureRevertCache.isPureRevert(
+        notes.getProjectName(),
+        ObjectId.fromString(notes.getCurrentPatchSet().getRevision().get()),
+        claimedOriginalObjectId);
   }
 }
diff --git a/java/com/google/gerrit/server/config/GerritGlobalModule.java b/java/com/google/gerrit/server/config/GerritGlobalModule.java
index e7baa55..f168ef9 100644
--- a/java/com/google/gerrit/server/config/GerritGlobalModule.java
+++ b/java/com/google/gerrit/server/config/GerritGlobalModule.java
@@ -117,6 +117,7 @@
 import com.google.gerrit.server.git.MergeUtil;
 import com.google.gerrit.server.git.MergedByPushOp;
 import com.google.gerrit.server.git.NotesBranchUtil;
+import com.google.gerrit.server.git.PureRevertCache;
 import com.google.gerrit.server.git.ReceivePackInitializer;
 import com.google.gerrit.server.git.TagCache;
 import com.google.gerrit.server.git.TransferConfig;
@@ -237,6 +238,7 @@
     install(SubmitStrategy.module());
     install(TagCache.module());
     install(OAuthTokenCache.module());
+    install(PureRevertCache.module());
 
     install(new AccessControlModule());
     install(new CmdLineParserModule());
diff --git a/java/com/google/gerrit/server/git/PureRevertCache.java b/java/com/google/gerrit/server/git/PureRevertCache.java
new file mode 100644
index 0000000..53f004f
--- /dev/null
+++ b/java/com/google/gerrit/server/git/PureRevertCache.java
@@ -0,0 +1,203 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// 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 com.google.gerrit.server.git;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Throwables;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.gerrit.extensions.restapi.BadRequestException;
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.cache.CacheModule;
+import com.google.gerrit.server.cache.proto.Cache;
+import com.google.gerrit.server.cache.proto.Cache.PureRevertKeyProto;
+import com.google.gerrit.server.cache.serialize.BooleanCacheSerializer;
+import com.google.gerrit.server.cache.serialize.ObjectIdConverter;
+import com.google.gerrit.server.cache.serialize.ProtobufSerializer;
+import com.google.gerrit.server.logging.TraceContext;
+import com.google.gerrit.server.notedb.ChangeNotes;
+import com.google.gerrit.server.project.ProjectCache;
+import com.google.gwtorm.server.OrmException;
+import com.google.inject.Inject;
+import com.google.inject.Module;
+import com.google.inject.Singleton;
+import com.google.inject.name.Named;
+import com.google.protobuf.ByteString;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.List;
+import java.util.concurrent.ExecutionException;
+import org.eclipse.jgit.diff.DiffEntry;
+import org.eclipse.jgit.diff.DiffFormatter;
+import org.eclipse.jgit.errors.InvalidObjectIdException;
+import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectInserter;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.merge.ThreeWayMerger;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
+
+/** Computes and caches if a change is a pure revert of another change. */
+@Singleton
+public class PureRevertCache {
+  private static final String ID_CACHE = "pure_revert";
+
+  public static Module module() {
+    return new CacheModule() {
+      @Override
+      protected void configure() {
+        persist(ID_CACHE, Cache.PureRevertKeyProto.class, Boolean.class)
+            .maximumWeight(100)
+            .loader(Loader.class)
+            .version(1)
+            .keySerializer(new ProtobufSerializer<>(Cache.PureRevertKeyProto.parser()))
+            .valueSerializer(BooleanCacheSerializer.INSTANCE);
+      }
+    };
+  }
+
+  private final LoadingCache<PureRevertKeyProto, Boolean> cache;
+  private final ChangeNotes.Factory notesFactory;
+
+  @Inject
+  PureRevertCache(
+      @Named(ID_CACHE) LoadingCache<PureRevertKeyProto, Boolean> cache,
+      ChangeNotes.Factory notesFactory) {
+    this.cache = cache;
+    this.notesFactory = notesFactory;
+  }
+
+  /**
+   * Returns {@code true} if {@code claimedRevert} is a pure (clean) revert of the change that is
+   * referenced in {@link Change#getRevertOf()}.
+   *
+   * @return {@code true} if {@code claimedRevert} is a pure (clean) revert.
+   * @throws IOException if there was a problem with the storage layer
+   * @throws OrmException if there was a problem with the storage layer
+   * @throws BadRequestException if there is a problem with the provided {@link ChangeNotes}
+   */
+  public boolean isPureRevert(ChangeNotes claimedRevert)
+      throws OrmException, IOException, BadRequestException {
+    if (claimedRevert.getChange().getRevertOf() == null) {
+      throw new BadRequestException("revertOf not set");
+    }
+    ChangeNotes claimedOriginal =
+        notesFactory.createChecked(
+            claimedRevert.getProjectName(), claimedRevert.getChange().getRevertOf());
+    return isPureRevert(
+        claimedRevert.getProjectName(),
+        ObjectId.fromString(claimedRevert.getCurrentPatchSet().getRevision().get()),
+        ObjectId.fromString(claimedOriginal.getCurrentPatchSet().getRevision().get()));
+  }
+
+  /**
+   * Returns {@code true} if {@code claimedRevert} is a pure (clean) revert of {@code
+   * claimedOriginal}.
+   *
+   * @return {@code true} if {@code claimedRevert} is a pure (clean) revert of {@code
+   *     claimedOriginal}.
+   * @throws IOException if there was a problem with the storage layer
+   * @throws BadRequestException if there is a problem with the provided {@link ObjectId}s
+   */
+  public boolean isPureRevert(
+      Project.NameKey project, ObjectId claimedRevert, ObjectId claimedOriginal)
+      throws IOException, BadRequestException {
+    try {
+      return cache.get(key(project, claimedRevert, claimedOriginal));
+    } catch (ExecutionException e) {
+      Throwables.throwIfInstanceOf(e.getCause(), BadRequestException.class);
+      throw new IOException(e);
+    }
+  }
+
+  @VisibleForTesting
+  static PureRevertKeyProto key(
+      Project.NameKey project, ObjectId claimedRevert, ObjectId claimedOriginal) {
+    ByteString original = ObjectIdConverter.create().toByteString(claimedOriginal);
+    ByteString revert = ObjectIdConverter.create().toByteString(claimedRevert);
+    return PureRevertKeyProto.newBuilder()
+        .setProject(project.get())
+        .setClaimedOriginal(original)
+        .setClaimedRevert(revert)
+        .build();
+  }
+
+  static class Loader extends CacheLoader<PureRevertKeyProto, Boolean> {
+    private final GitRepositoryManager repoManager;
+    private final MergeUtil.Factory mergeUtilFactory;
+    private final ProjectCache projectCache;
+
+    @Inject
+    Loader(
+        GitRepositoryManager repoManager,
+        MergeUtil.Factory mergeUtilFactory,
+        ProjectCache projectCache) {
+      this.repoManager = repoManager;
+      this.mergeUtilFactory = mergeUtilFactory;
+      this.projectCache = projectCache;
+    }
+
+    @Override
+    public Boolean load(PureRevertKeyProto key) throws BadRequestException, IOException {
+      try (TraceContext.TraceTimer ignored =
+          TraceContext.newTimer("Loading pure revert for %s", key)) {
+        ObjectId original = ObjectIdConverter.create().fromByteString(key.getClaimedOriginal());
+        ObjectId revert = ObjectIdConverter.create().fromByteString(key.getClaimedRevert());
+        Project.NameKey project = new Project.NameKey(key.getProject());
+
+        try (Repository repo = repoManager.openRepository(project);
+            ObjectInserter oi = repo.newObjectInserter();
+            RevWalk rw = new RevWalk(repo)) {
+          RevCommit claimedOriginalCommit;
+          try {
+            claimedOriginalCommit = rw.parseCommit(original);
+          } catch (InvalidObjectIdException | MissingObjectException e) {
+            throw new BadRequestException("invalid object ID");
+          }
+          if (claimedOriginalCommit.getParentCount() == 0) {
+            throw new BadRequestException("can't check against initial commit");
+          }
+          RevCommit claimedRevertCommit = rw.parseCommit(revert);
+          if (claimedRevertCommit.getParentCount() == 0) {
+            return false;
+          }
+          // Rebase claimed revert onto claimed original
+          ThreeWayMerger merger =
+              mergeUtilFactory
+                  .create(projectCache.checkedGet(project))
+                  .newThreeWayMerger(oi, repo.getConfig());
+          merger.setBase(claimedRevertCommit.getParent(0));
+          boolean success = merger.merge(claimedRevertCommit, claimedOriginalCommit);
+          if (!success || merger.getResultTreeId() == null) {
+            // Merge conflict during rebase
+            return false;
+          }
+
+          // Any differences between claimed original's parent and the rebase result indicate that
+          // the
+          // claimedRevert is not a pure revert but made content changes
+          try (DiffFormatter df = new DiffFormatter(new ByteArrayOutputStream())) {
+            df.setReader(oi.newReader(), repo.getConfig());
+            List<DiffEntry> entries =
+                df.scan(claimedOriginalCommit.getParent(0), merger.getResultTreeId());
+            return entries.isEmpty();
+          }
+        }
+      }
+    }
+  }
+}
diff --git a/java/com/google/gerrit/server/query/change/ChangeData.java b/java/com/google/gerrit/server/query/change/ChangeData.java
index b058166..5a300b4 100644
--- a/java/com/google/gerrit/server/query/change/ChangeData.java
+++ b/java/com/google/gerrit/server/query/change/ChangeData.java
@@ -1111,7 +1111,7 @@
       return null;
     }
     try {
-      return pureRevert.get(notes(), null).isPureRevert;
+      return pureRevert.get(notes(), Optional.empty());
     } catch (IOException | BadRequestException | ResourceConflictException e) {
       throw new OrmException("could not compute pure revert", e);
     }
diff --git a/java/com/google/gerrit/server/restapi/change/GetPureRevert.java b/java/com/google/gerrit/server/restapi/change/GetPureRevert.java
index 75019af..dcafe56 100644
--- a/java/com/google/gerrit/server/restapi/change/GetPureRevert.java
+++ b/java/com/google/gerrit/server/restapi/change/GetPureRevert.java
@@ -25,6 +25,7 @@
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import java.io.IOException;
+import java.util.Optional;
 import org.kohsuke.args4j.Option;
 
 public class GetPureRevert implements RestReadView<ChangeResource> {
@@ -49,6 +50,7 @@
   public PureRevertInfo apply(ChangeResource rsrc)
       throws ResourceConflictException, IOException, BadRequestException, OrmException,
           AuthException {
-    return pureRevert.get(rsrc.getNotes(), claimedOriginal);
+    boolean isPureRevert = pureRevert.get(rsrc.getNotes(), Optional.ofNullable(claimedOriginal));
+    return new PureRevertInfo(isPureRevert);
   }
 }
diff --git a/javatests/com/google/gerrit/acceptance/api/change/ChangeIT.java b/javatests/com/google/gerrit/acceptance/api/change/ChangeIT.java
index 9cc277f..5aed312 100644
--- a/javatests/com/google/gerrit/acceptance/api/change/ChangeIT.java
+++ b/javatests/com/google/gerrit/acceptance/api/change/ChangeIT.java
@@ -3695,7 +3695,7 @@
   @Test
   public void pureRevertThrowsExceptionWhenChangeIsNotARevertAndNoIdProvided() throws Exception {
     exception.expect(BadRequestException.class);
-    exception.expectMessage("no ID was provided and change isn't a revert");
+    exception.expectMessage("revertOf not set");
     gApi.changes().id(createChange().getChangeId()).pureRevert();
   }
 
diff --git a/javatests/com/google/gerrit/server/cache/serialize/BUILD b/javatests/com/google/gerrit/server/cache/serialize/BUILD
index ddad4b9..92f33ad 100644
--- a/javatests/com/google/gerrit/server/cache/serialize/BUILD
+++ b/javatests/com/google/gerrit/server/cache/serialize/BUILD
@@ -17,5 +17,6 @@
         "//lib/truth",
         "//lib/truth:truth-proto-extension",
         "//proto:cache_java_proto",
+        "//proto/testing:test_java_proto",
     ],
 )
diff --git a/javatests/com/google/gerrit/server/cache/serialize/ProtobufSerializerTest.java b/javatests/com/google/gerrit/server/cache/serialize/ProtobufSerializerTest.java
new file mode 100644
index 0000000..845da9b
--- /dev/null
+++ b/javatests/com/google/gerrit/server/cache/serialize/ProtobufSerializerTest.java
@@ -0,0 +1,43 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// 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 com.google.gerrit.server.cache.serialize;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.gerrit.proto.testing.Test.SerializableProto;
+import com.google.gerrit.testing.GerritBaseTests;
+import org.junit.Test;
+
+public class ProtobufSerializerTest extends GerritBaseTests {
+  @Test
+  public void requiredAndOptionalTypes() {
+    assertRoundTrip(SerializableProto.newBuilder().setId(123));
+    assertRoundTrip(SerializableProto.newBuilder().setId(123).setText("foo bar"));
+  }
+
+  @Test
+  public void exactByteSequence() {
+    ProtobufSerializer<SerializableProto> s = new ProtobufSerializer<>(SerializableProto.parser());
+    SerializableProto proto = SerializableProto.newBuilder().setId(123).setText("foo bar").build();
+    byte[] serialized = s.serialize(proto);
+    // Hard-code byte sequence to detect library changes
+    assertThat(serialized).isEqualTo(new byte[] {8, 123, 18, 7, 102, 111, 111, 32, 98, 97, 114});
+  }
+
+  private static void assertRoundTrip(SerializableProto.Builder input) {
+    ProtobufSerializer<SerializableProto> s = new ProtobufSerializer<>(SerializableProto.parser());
+    assertThat(s.deserialize(s.serialize(input.build()))).isEqualTo(input.build());
+  }
+}
diff --git a/javatests/com/google/gerrit/server/git/PureRevertCacheKeyTest.java b/javatests/com/google/gerrit/server/git/PureRevertCacheKeyTest.java
new file mode 100644
index 0000000..8c17075
--- /dev/null
+++ b/javatests/com/google/gerrit/server/git/PureRevertCacheKeyTest.java
@@ -0,0 +1,49 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// 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 com.google.gerrit.server.git;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.gerrit.server.cache.testing.CacheSerializerTestUtil.byteArray;
+
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.cache.proto.Cache;
+import com.google.protobuf.ByteString;
+import org.eclipse.jgit.lib.ObjectId;
+import org.junit.Test;
+
+public class PureRevertCacheKeyTest {
+  @Test
+  public void serialization() {
+    ObjectId revert = ObjectId.zeroId();
+    ObjectId original = ObjectId.fromString("aabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb");
+
+    byte[] serializedRevert =
+        new byte[] {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+    byte[] serializedOriginal =
+        byteArray(
+            0xaa, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb,
+            0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb);
+
+    Cache.PureRevertKeyProto key =
+        PureRevertCache.key(new Project.NameKey("test"), revert, original);
+    assertThat(key)
+        .isEqualTo(
+            Cache.PureRevertKeyProto.newBuilder()
+                .setProject("test")
+                .setClaimedRevert(ByteString.copyFrom(serializedRevert))
+                .setClaimedOriginal(ByteString.copyFrom(serializedOriginal))
+                .build());
+  }
+}
diff --git a/proto/cache.proto b/proto/cache.proto
index c978069..b34dbf3 100644
--- a/proto/cache.proto
+++ b/proto/cache.proto
@@ -234,3 +234,11 @@
   }
   repeated ExternalIdProto external_id = 1;
 }
+
+// Key for com.google.gerrit.server.git.PureRevertCache.
+// Next ID: 4
+message PureRevertKeyProto {
+  string project = 1;
+  bytes claimed_original = 2;
+  bytes claimed_revert = 3;
+}
diff --git a/proto/testing/BUILD b/proto/testing/BUILD
new file mode 100644
index 0000000..b9032cf
--- /dev/null
+++ b/proto/testing/BUILD
@@ -0,0 +1,12 @@
+proto_library(
+    name = "test_proto",
+    testonly = 1,
+    srcs = ["test.proto"],
+)
+
+java_proto_library(
+    name = "test_java_proto",
+    testonly = 1,
+    visibility = ["//visibility:public"],
+    deps = [":test_proto"],
+)
diff --git a/proto/testing/test.proto b/proto/testing/test.proto
new file mode 100644
index 0000000..e28c9ff
--- /dev/null
+++ b/proto/testing/test.proto
@@ -0,0 +1,26 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// 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.
+
+syntax = "proto2";
+
+package devtools.gerritcodereview.testing;
+
+option java_package = "com.google.gerrit.proto.testing";
+
+// Test type for ProtobufSerializerTest
+// Next ID: 3
+message SerializableProto {
+  required int32 id = 1;
+  optional string text = 2;
+}