diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionInputHelper.java b/src/main/java/com/google/devtools/build/lib/actions/ActionInputHelper.java
index ea5f758..bc3d15c 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionInputHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionInputHelper.java
@@ -103,12 +103,19 @@
   }
 
   /**
-   * Expands middleman artifacts in a sequence of {@link ActionInput}s.
+   * Expands middleman and tree artifacts in a sequence of {@link ActionInput}s.
    *
-   * <p>Non-middleman artifacts are returned untouched.
+   * <p>The constructed list never contains middleman artifacts. If {@code keepEmptyTreeArtifacts}
+   * is true, a tree artifact will be included in the constructed list when it expands into zero
+   * file artifacts. Otherwise, only the file artifacts the tree artifact expands into will be
+   * included.
+   *
+   * <p>Non-middleman, non-tree artifacts are returned untouched.
    */
   public static List<ActionInput> expandArtifacts(
-      NestedSet<? extends ActionInput> inputs, ArtifactExpander artifactExpander) {
+      NestedSet<? extends ActionInput> inputs,
+      ArtifactExpander artifactExpander,
+      boolean keepEmptyTreeArtifacts) {
     List<ActionInput> result = new ArrayList<>();
     List<Artifact> containedArtifacts = new ArrayList<>();
     for (ActionInput input : inputs.toList()) {
@@ -118,7 +125,8 @@
       }
       containedArtifacts.add((Artifact) input);
     }
-    Artifact.addExpandedArtifacts(containedArtifacts, result, artifactExpander);
+    Artifact.addExpandedArtifacts(
+        containedArtifacts, result, artifactExpander, keepEmptyTreeArtifacts);
     return result;
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
index cb0afd2..3082064 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
@@ -1566,42 +1566,63 @@
     return Joiner.on(delimiter).join(toRootRelativePaths(artifacts));
   }
 
-  /** Adds a collection of artifacts to a given collection, with middleman actions expanded once. */
+  /**
+   * Adds a collection of artifacts to a given collection, with middleman actions and tree artifacts
+   * expanded once.
+   *
+   * <p>The constructed list never contains middleman artifacts. If {@code keepEmptyTreeArtifacts}
+   * is true, a tree artifact will be included in the constructed list when it expands into zero
+   * file artifacts. Otherwise, only the file artifacts the tree artifact expands into will be
+   * included.
+   */
   static void addExpandedArtifacts(
       Iterable<Artifact> artifacts,
       Collection<? super Artifact> output,
-      ArtifactExpander artifactExpander) {
-    addExpandedArtifacts(artifacts, output, Functions.identity(), artifactExpander);
+      ArtifactExpander artifactExpander,
+      boolean keepEmptyTreeArtifacts) {
+    addExpandedArtifacts(
+        artifacts, output, Functions.identity(), artifactExpander, keepEmptyTreeArtifacts);
   }
 
   /**
-   * Converts a collection of artifacts into the outputs computed by
-   * outputFormatter and adds them to a given collection. Middleman artifacts
-   * are expanded once.
+   * Converts a collection of artifacts into the outputs computed by outputFormatter and adds them
+   * to a given collection. Middleman artifacts and tree artifacts are expanded once.
+   *
+   * <p>The constructed list never contains middleman artifacts. If {@code keepEmptyTreeArtifacts}
+   * is true, a tree artifact will be included in the constructed list when it expands into zero
+   * file artifacts. Otherwise, only the file artifacts the tree artifact expands into will be
+   * included.
    */
-  private static <E> void addExpandedArtifacts(Iterable<? extends Artifact> artifacts,
-                                               Collection<? super E> output,
-                                               Function<? super Artifact, E> outputFormatter,
-                                               ArtifactExpander artifactExpander) {
+  private static <E> void addExpandedArtifacts(
+      Iterable<? extends Artifact> artifacts,
+      Collection<? super E> output,
+      Function<? super Artifact, E> outputFormatter,
+      ArtifactExpander artifactExpander,
+      boolean keepEmptyTreeArtifacts) {
     for (Artifact artifact : artifacts) {
       if (artifact.isMiddlemanArtifact() || artifact.isTreeArtifact()) {
-        expandArtifact(artifact, output, outputFormatter, artifactExpander);
+        expandArtifact(artifact, output, outputFormatter, artifactExpander, keepEmptyTreeArtifacts);
       } else {
         output.add(outputFormatter.apply(artifact));
       }
     }
   }
 
-  private static <E> void expandArtifact(Artifact middleman,
+  private static <E> void expandArtifact(
+      Artifact middleman,
       Collection<? super E> output,
       Function<? super Artifact, E> outputFormatter,
-      ArtifactExpander artifactExpander) {
+      ArtifactExpander artifactExpander,
+      boolean keepEmptyTreeArtifacts) {
     Preconditions.checkArgument(middleman.isMiddlemanArtifact() || middleman.isTreeArtifact());
     List<Artifact> artifacts = new ArrayList<>();
     artifactExpander.expand(middleman, artifacts);
     for (Artifact artifact : artifacts) {
       output.add(outputFormatter.apply(artifact));
     }
+    if (keepEmptyTreeArtifacts && middleman.isTreeArtifact() && artifacts.isEmpty()) {
+      output.add(outputFormatter.apply(middleman));
+    }
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/exec/SpawnInputExpander.java b/src/main/java/com/google/devtools/build/lib/exec/SpawnInputExpander.java
index 44cb021..944892e 100644
--- a/src/main/java/com/google/devtools/build/lib/exec/SpawnInputExpander.java
+++ b/src/main/java/com/google/devtools/build/lib/exec/SpawnInputExpander.java
@@ -130,7 +130,9 @@
           if (localArtifact.isTreeArtifact()) {
             List<ActionInput> expandedInputs =
                 ActionInputHelper.expandArtifacts(
-                    NestedSetBuilder.create(Order.STABLE_ORDER, localArtifact), artifactExpander);
+                    NestedSetBuilder.create(Order.STABLE_ORDER, localArtifact),
+                    artifactExpander,
+                    /* keepEmptyTreeArtifacts= */ false);
             for (ActionInput input : expandedInputs) {
               addMapping(
                   inputMap,
@@ -222,7 +224,12 @@
       NestedSet<? extends ActionInput> inputFiles,
       ArtifactExpander artifactExpander,
       PathFragment baseDirectory) {
-    List<ActionInput> inputs = ActionInputHelper.expandArtifacts(inputFiles, artifactExpander);
+    // Actions that accept TreeArtifacts as inputs generally expect the directory corresponding
+    // to the artifact to be created, even if it is empty. We explicitly keep empty TreeArtifacts
+    // here to signal consumers that they should create the directory.
+    List<ActionInput> inputs =
+        ActionInputHelper.expandArtifacts(
+            inputFiles, artifactExpander, /* keepEmptyTreeArtifacts= */ true);
     for (ActionInput input : inputs) {
       addMapping(inputMap, input.getExecPath(), input, baseDirectory);
     }
@@ -230,8 +237,10 @@
 
   /**
    * Convert the inputs and runfiles of the given spawn to a map from exec-root relative paths to
-   * {@link ActionInput}s. The returned map does not contain tree artifacts as they are expanded to
-   * file artifacts.
+   * {@link ActionInput}s. The returned map does not contain non-empty tree artifacts as they are
+   * expanded to file artifacts. Tree artifacts that would expand to the empty set under the
+   * provided {@link ArtifactExpander} are left untouched so that their corresponding empty
+   * directories can be created.
    *
    * <p>The returned map never contains {@code null} values.
    *
diff --git a/src/main/java/com/google/devtools/build/lib/exec/StandaloneTestStrategy.java b/src/main/java/com/google/devtools/build/lib/exec/StandaloneTestStrategy.java
index ef99dae..24405a4 100644
--- a/src/main/java/com/google/devtools/build/lib/exec/StandaloneTestStrategy.java
+++ b/src/main/java/com/google/devtools/build/lib/exec/StandaloneTestStrategy.java
@@ -591,7 +591,6 @@
             .addTransitive(action.getInputs())
             .addAll(expandedCoverageDir)
             .add(action.getCollectCoverageScript())
-            .add(action.getCoverageDirectoryTreeArtifact())
             .add(action.getCoverageManifest())
             .addTransitive(action.getLcovMergerFilesToRun().build())
             .build(),
diff --git a/src/main/java/com/google/devtools/build/lib/remote/merkletree/BUILD b/src/main/java/com/google/devtools/build/lib/remote/merkletree/BUILD
index 46283f2..b7831a8 100644
--- a/src/main/java/com/google/devtools/build/lib/remote/merkletree/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/remote/merkletree/BUILD
@@ -20,6 +20,7 @@
         "//src/main/java/com/google/devtools/build/lib/actions:file_metadata",
         "//src/main/java/com/google/devtools/build/lib/profiler",
         "//src/main/java/com/google/devtools/build/lib/remote/util",
+        "//src/main/java/com/google/devtools/build/lib/skyframe:tree_artifact_value",
         "//src/main/java/com/google/devtools/build/lib/vfs",
         "//src/main/java/com/google/devtools/build/lib/vfs:pathfragment",
         "//third_party:guava",
diff --git a/src/main/java/com/google/devtools/build/lib/remote/merkletree/DirectoryTreeBuilder.java b/src/main/java/com/google/devtools/build/lib/remote/merkletree/DirectoryTreeBuilder.java
index a29304b..c641f80 100644
--- a/src/main/java/com/google/devtools/build/lib/remote/merkletree/DirectoryTreeBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/remote/merkletree/DirectoryTreeBuilder.java
@@ -17,12 +17,14 @@
 import com.google.common.base.Preconditions;
 import com.google.devtools.build.lib.actions.ActionInput;
 import com.google.devtools.build.lib.actions.ActionInputHelper;
+import com.google.devtools.build.lib.actions.Artifact.DerivedArtifact;
 import com.google.devtools.build.lib.actions.FileArtifactValue;
 import com.google.devtools.build.lib.actions.MetadataProvider;
 import com.google.devtools.build.lib.actions.cache.VirtualActionInput;
 import com.google.devtools.build.lib.remote.merkletree.DirectoryTree.DirectoryNode;
 import com.google.devtools.build.lib.remote.merkletree.DirectoryTree.FileNode;
 import com.google.devtools.build.lib.remote.util.DigestUtil;
+import com.google.devtools.build.lib.skyframe.TreeArtifactValue;
 import com.google.devtools.build.lib.vfs.Dirent;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
@@ -33,6 +35,7 @@
 import java.util.Map;
 import java.util.SortedMap;
 import java.util.TreeMap;
+import javax.annotation.Nullable;
 
 /** Builder for directory trees. */
 class DirectoryTreeBuilder {
@@ -94,6 +97,7 @@
       Map<PathFragment, DirectoryNode> tree)
       throws IOException {
     return build(
+        null,
         inputs,
         tree,
         (input, path, currDir) -> {
@@ -122,6 +126,7 @@
       Map<PathFragment, DirectoryNode> tree)
       throws IOException {
     return build(
+        metadataProvider,
         inputs,
         tree,
         (input, path, currDir) -> {
@@ -177,6 +182,7 @@
   }
 
   private static <T> int build(
+      @Nullable MetadataProvider metadataProvider,
       SortedMap<PathFragment, T> inputs,
       Map<PathFragment, DirectoryNode> tree,
       FileNodeVisitor<T> fileNodeVisitor)
@@ -192,6 +198,32 @@
       // Path relative to the exec root
       PathFragment path = e.getKey();
       T input = e.getValue();
+
+      if (input instanceof DerivedArtifact && ((DerivedArtifact) input).isTreeArtifact()) {
+        DerivedArtifact artifact = (DerivedArtifact) input;
+        // MetadataProvider is provided by all callers for which T is a superclass of
+        // DerivedArtifact.
+        Preconditions.checkNotNull(metadataProvider);
+        FileArtifactValue metadata =
+            Preconditions.checkNotNull(
+                metadataProvider.getMetadata(artifact),
+                "missing metadata for '%s'",
+                artifact.getExecPathString());
+        Preconditions.checkState(
+            metadata.equals(TreeArtifactValue.empty().getMetadata()),
+            "Encountered non-empty TreeArtifact '%s' with metadata '%s', which should have"
+                + " been expanded by SpawnInputExpander. This is a bug.",
+            path,
+            metadata);
+        // Create an empty directory and its parent directories but don't visit the TreeArtifact
+        // input itself: A TreeArtifact's metadata has type REGULAR_FILE, not DIRECTORY, and would
+        // thus lead to an empty file being created in the buildFromActionInputs visitor.
+        DirectoryNode emptyDir = new DirectoryNode(path.getBaseName());
+        tree.put(path, emptyDir);
+        createParentDirectoriesIfNotExist(path, emptyDir, tree);
+        continue;
+      }
+
       if (dirname == null || !path.getParentDirectory().equals(dirname)) {
         dirname = path.getParentDirectory();
         dir = tree.get(dirname);
diff --git a/src/main/java/com/google/devtools/build/lib/remote/merkletree/MerkleTree.java b/src/main/java/com/google/devtools/build/lib/remote/merkletree/MerkleTree.java
index f519402..97df073 100644
--- a/src/main/java/com/google/devtools/build/lib/remote/merkletree/MerkleTree.java
+++ b/src/main/java/com/google/devtools/build/lib/remote/merkletree/MerkleTree.java
@@ -252,7 +252,8 @@
           for (DirectoryTree.DirectoryNode dir : dirs) {
             PathFragment subDirname = dirname.getRelative(dir.getPathSegment());
             MerkleTree subMerkleTree =
-                Preconditions.checkNotNull(m.remove(subDirname), "subMerkleTree was null");
+                Preconditions.checkNotNull(
+                    m.remove(subDirname), "subMerkleTree at '%s' was null", subDirname);
             subDirs.put(dir.getPathSegment(), subMerkleTree);
           }
           MerkleTree mt = buildMerkleTree(new TreeSet<>(files), subDirs, digestUtil);
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/DarwinSandboxedSpawnRunner.java b/src/main/java/com/google/devtools/build/lib/sandbox/DarwinSandboxedSpawnRunner.java
index d1f5ec2..630a455 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/DarwinSandboxedSpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/DarwinSandboxedSpawnRunner.java
@@ -233,8 +233,6 @@
     SandboxInputs inputs =
         helpers.processInputFiles(
             context.getInputMapping(PathFragment.EMPTY_FRAGMENT),
-            spawn,
-            context.getArtifactExpander(),
             execRoot);
     SandboxOutputs outputs = helpers.getOutputs(spawn);
 
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/DockerSandboxedSpawnRunner.java b/src/main/java/com/google/devtools/build/lib/sandbox/DockerSandboxedSpawnRunner.java
index f56eafd..1a46186 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/DockerSandboxedSpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/DockerSandboxedSpawnRunner.java
@@ -223,8 +223,6 @@
     SandboxInputs inputs =
         helpers.processInputFiles(
             context.getInputMapping(PathFragment.EMPTY_FRAGMENT),
-            spawn,
-            context.getArtifactExpander(),
             execRoot);
     SandboxOutputs outputs = helpers.getOutputs(spawn);
 
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedSpawnRunner.java b/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedSpawnRunner.java
index ffb7a5f..b9fdbf3 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedSpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedSpawnRunner.java
@@ -184,8 +184,6 @@
     SandboxInputs inputs =
         helpers.processInputFiles(
             context.getInputMapping(PathFragment.EMPTY_FRAGMENT),
-            spawn,
-            context.getArtifactExpander(),
             execRoot);
     SandboxOutputs outputs = helpers.getOutputs(spawn);
 
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/ProcessWrapperSandboxedSpawnRunner.java b/src/main/java/com/google/devtools/build/lib/sandbox/ProcessWrapperSandboxedSpawnRunner.java
index 79b625e..6b6835e 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/ProcessWrapperSandboxedSpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/ProcessWrapperSandboxedSpawnRunner.java
@@ -112,8 +112,6 @@
     SandboxInputs inputs =
         helpers.processInputFiles(
             context.getInputMapping(PathFragment.EMPTY_FRAGMENT),
-            spawn,
-            context.getArtifactExpander(),
             execRoot);
     SandboxOutputs outputs = helpers.getOutputs(spawn);
 
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/SandboxHelpers.java b/src/main/java/com/google/devtools/build/lib/sandbox/SandboxHelpers.java
index 4d088b0..26335ec 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/SandboxHelpers.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/SandboxHelpers.java
@@ -25,7 +25,6 @@
 import com.google.common.flogger.GoogleLogger;
 import com.google.devtools.build.lib.actions.ActionInput;
 import com.google.devtools.build.lib.actions.Artifact;
-import com.google.devtools.build.lib.actions.Artifact.ArtifactExpander;
 import com.google.devtools.build.lib.actions.Spawn;
 import com.google.devtools.build.lib.actions.cache.VirtualActionInput;
 import com.google.devtools.build.lib.actions.cache.VirtualActionInput.EmptyActionInput;
@@ -40,10 +39,8 @@
 import com.google.devtools.common.options.OptionsParsingResult;
 import java.io.IOException;
 import java.io.OutputStream;
-import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
-import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
@@ -429,27 +426,8 @@
    */
   public SandboxInputs processInputFiles(
       Map<PathFragment, ActionInput> inputMap,
-      Spawn spawn,
-      ArtifactExpander artifactExpander,
       Path execRoot)
       throws IOException {
-    // SpawnInputExpander#getInputMapping uses ArtifactExpander#expandArtifacts to expand
-    // middlemen and tree artifacts, which expands empty tree artifacts to no entry. However,
-    // actions that accept TreeArtifacts as inputs generally expect that the empty directory is
-    // created. So we add those explicitly here.
-    // TODO(ulfjack): Move this code to SpawnInputExpander.
-    for (ActionInput input : spawn.getInputFiles().toList()) {
-      if (input instanceof Artifact && ((Artifact) input).isTreeArtifact()) {
-        List<Artifact> containedArtifacts = new ArrayList<>();
-        artifactExpander.expand((Artifact) input, containedArtifacts);
-        // Attempting to mount a non-empty directory results in ERR_DIRECTORY_NOT_EMPTY, so we
-        // only mount empty TreeArtifacts as directories.
-        if (containedArtifacts.isEmpty()) {
-          inputMap.put(input.getExecPath(), input);
-        }
-      }
-    }
-
     Map<PathFragment, Path> inputFiles = new TreeMap<>();
     Set<VirtualActionInput> virtualInputs = new HashSet<>();
     Map<PathFragment, PathFragment> inputSymlinks = new TreeMap<>();
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/WindowsSandboxedSpawnRunner.java b/src/main/java/com/google/devtools/build/lib/sandbox/WindowsSandboxedSpawnRunner.java
index f602fab..3be3a54 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/WindowsSandboxedSpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/WindowsSandboxedSpawnRunner.java
@@ -72,8 +72,6 @@
     SandboxInputs readablePaths =
         helpers.processInputFiles(
             context.getInputMapping(PathFragment.EMPTY_FRAGMENT),
-            spawn,
-            context.getArtifactExpander(),
             execRoot);
 
     readablePaths.materializeVirtualInputs(execRoot);
diff --git a/src/main/java/com/google/devtools/build/lib/worker/WorkerFilesHash.java b/src/main/java/com/google/devtools/build/lib/worker/WorkerFilesHash.java
index f0246c3..c01a7ea 100644
--- a/src/main/java/com/google/devtools/build/lib/worker/WorkerFilesHash.java
+++ b/src/main/java/com/google/devtools/build/lib/worker/WorkerFilesHash.java
@@ -58,7 +58,8 @@
     TreeMap<PathFragment, HashCode> workerFilesMap = new TreeMap<>();
 
     List<ActionInput> tools =
-        ActionInputHelper.expandArtifacts(spawn.getToolFiles(), artifactExpander);
+        ActionInputHelper.expandArtifacts(
+            spawn.getToolFiles(), artifactExpander, /* keepEmptyTreeArtifacts= */ false);
     for (ActionInput tool : tools) {
       workerFilesMap.put(
           tool.getExecPath(),
diff --git a/src/main/java/com/google/devtools/build/lib/worker/WorkerSpawnRunner.java b/src/main/java/com/google/devtools/build/lib/worker/WorkerSpawnRunner.java
index 6eb0b73..a5466f6 100644
--- a/src/main/java/com/google/devtools/build/lib/worker/WorkerSpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/worker/WorkerSpawnRunner.java
@@ -192,8 +192,6 @@
         inputFiles =
             helpers.processInputFiles(
                 context.getInputMapping(PathFragment.EMPTY_FRAGMENT),
-                spawn,
-                context.getArtifactExpander(),
                 execRoot);
       }
       SandboxOutputs outputs = helpers.getOutputs(spawn);
@@ -250,7 +248,10 @@
     }
 
     List<ActionInput> inputs =
-        ActionInputHelper.expandArtifacts(spawn.getInputFiles(), context.getArtifactExpander());
+        ActionInputHelper.expandArtifacts(
+            spawn.getInputFiles(),
+            context.getArtifactExpander(),
+            /* keepEmptyTreeArtifacts= */ false);
 
     for (ActionInput input : inputs) {
       byte[] digestBytes = inputFileCache.getMetadata(input).getDigest();
diff --git a/src/test/java/com/google/devtools/build/lib/sandbox/SandboxHelpersTest.java b/src/test/java/com/google/devtools/build/lib/sandbox/SandboxHelpersTest.java
index 61fa766..f8ed2c3 100644
--- a/src/test/java/com/google/devtools/build/lib/sandbox/SandboxHelpersTest.java
+++ b/src/test/java/com/google/devtools/build/lib/sandbox/SandboxHelpersTest.java
@@ -24,14 +24,11 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.actions.ActionInput;
-import com.google.devtools.build.lib.actions.Artifact.ArtifactExpander;
 import com.google.devtools.build.lib.actions.CommandLines.ParamFileActionInput;
 import com.google.devtools.build.lib.actions.ParameterFile.ParameterFileType;
-import com.google.devtools.build.lib.actions.Spawn;
 import com.google.devtools.build.lib.actions.cache.VirtualActionInput;
 import com.google.devtools.build.lib.actions.util.ActionsTestUtil;
 import com.google.devtools.build.lib.exec.BinTools;
-import com.google.devtools.build.lib.exec.util.SpawnBuilder;
 import com.google.devtools.build.lib.sandbox.SandboxHelpers.SandboxInputs;
 import com.google.devtools.build.lib.sandbox.SandboxHelpers.SandboxOutputs;
 import com.google.devtools.build.lib.testutil.Scratch;
@@ -66,9 +63,6 @@
 @RunWith(JUnit4.class)
 public class SandboxHelpersTest {
 
-  private static final ArtifactExpander EMPTY_EXPANDER = (ignored1, ignored2) -> {};
-  private static final Spawn SPAWN = new SpawnBuilder().build();
-
   private final Scratch scratch = new Scratch();
   private Path execRoot;
   @Nullable private ExecutorService executorToCleanup;
@@ -98,8 +92,7 @@
             ParameterFileType.UNQUOTED,
             UTF_8);
 
-    SandboxInputs inputs =
-        sandboxHelpers.processInputFiles(inputMap(paramFile), SPAWN, EMPTY_EXPANDER, execRoot);
+    SandboxInputs inputs = sandboxHelpers.processInputFiles(inputMap(paramFile), execRoot);
 
     assertThat(inputs.getFiles())
         .containsExactly(PathFragment.create("paramFile"), execRoot.getChild("paramFile"));
@@ -118,8 +111,7 @@
             scratch.file("tool", "#!/bin/bash", "echo hello"),
             PathFragment.create("_bin/say_hello"));
 
-    SandboxInputs inputs =
-        sandboxHelpers.processInputFiles(inputMap(tool), SPAWN, EMPTY_EXPANDER, execRoot);
+    SandboxInputs inputs = sandboxHelpers.processInputFiles(inputMap(tool), execRoot);
 
     assertThat(inputs.getFiles())
         .containsExactly(
@@ -142,8 +134,7 @@
             ParameterFileType.UNQUOTED,
             UTF_8);
 
-    SandboxInputs inputs =
-        sandboxHelpers.processInputFiles(inputMap(paramFile), SPAWN, EMPTY_EXPANDER, execRoot);
+    SandboxInputs inputs = sandboxHelpers.processInputFiles(inputMap(paramFile), execRoot);
 
     assertThat(inputs.getFiles()).isEmpty();
     assertThat(inputs.getSymlinks()).isEmpty();
@@ -163,9 +154,7 @@
     BinTools.PathActionInput tool =
         new BinTools.PathActionInput(
             scratch.file("tool", "tool_code"), PathFragment.create("tools/tool"));
-    SandboxInputs inputs =
-        sandboxHelpers.processInputFiles(
-            inputMap(paramFile, tool), SPAWN, EMPTY_EXPANDER, execRoot);
+    SandboxInputs inputs = sandboxHelpers.processInputFiles(inputMap(paramFile, tool), execRoot);
 
     inputs.materializeVirtualInputs(scratch.dir("/sandbox"));
 
@@ -212,14 +201,13 @@
         executorToCleanup.submit(
             () -> {
               try {
-                sandboxHelpers.processInputFiles(
-                    inputMap(input), SPAWN, EMPTY_EXPANDER, customExecRoot);
+                sandboxHelpers.processInputFiles(inputMap(input), customExecRoot);
                 finishProcessingSemaphore.release();
               } catch (IOException e) {
                 throw new IllegalArgumentException(e);
               }
             });
-    sandboxHelpers.processInputFiles(inputMap(input), SPAWN, EMPTY_EXPANDER, customExecRoot);
+    sandboxHelpers.processInputFiles(inputMap(input), customExecRoot);
     finishProcessingSemaphore.release();
     future.get();
 
diff --git a/src/test/shell/bazel/bazel_sandboxing_test.sh b/src/test/shell/bazel/bazel_sandboxing_test.sh
index 3e42153..a11e712 100755
--- a/src/test/shell/bazel/bazel_sandboxing_test.sh
+++ b/src/test/shell/bazel/bazel_sandboxing_test.sh
@@ -794,7 +794,7 @@
 }
 
 # regression test for https://github.com/bazelbuild/bazel/issues/6262
-function test_create_tree_artifact_inputs() {
+function test_create_tree_artifact_outputs() {
   create_workspace_with_default_repos WORKSPACE
 
   cat > def.bzl <<'EOF'
@@ -818,6 +818,40 @@
   bazel build --test_output=streamed :a &>$TEST_log || fail "expected build to succeed"
 }
 
+function test_empty_tree_artifact_as_inputs() {
+  # Test that when an empty tree artifact is the input, an empty directory is
+  # created in the sandbox for action to read.
+  create_workspace_with_default_repos WORKSPACE
+
+  mkdir -p pkg
+
+  cat > pkg/def.bzl <<'EOF'
+def _r(ctx):
+    empty_d = ctx.actions.declare_directory("%s/empty_dir" % ctx.label.name)
+    ctx.actions.run_shell(
+        outputs = [empty_d],
+        command = "mkdir -p %s" % empty_d.path,
+    )
+    f = ctx.actions.declare_file("%s/file" % ctx.label.name)
+    ctx.actions.run_shell(
+        inputs = [empty_d],
+        outputs = [f],
+        command = "touch %s && cd %s && pwd" % (f.path, empty_d.path),
+    )
+    return [DefaultInfo(files = depset([f]))]
+
+r = rule(implementation = _r)
+EOF
+
+cat > pkg/BUILD <<'EOF'
+load(":def.bzl", "r")
+
+r(name = "a")
+EOF
+
+  bazel build //pkg:a &>$TEST_log || fail "expected build to succeed"
+}
+
 # The test shouldn't fail if the environment doesn't support running it.
 check_sandbox_allowed || exit 0
 
diff --git a/src/test/shell/bazel/remote/remote_execution_test.sh b/src/test/shell/bazel/remote/remote_execution_test.sh
index d84afa5..8731a7b 100755
--- a/src/test/shell/bazel/remote/remote_execution_test.sh
+++ b/src/test/shell/bazel/remote/remote_execution_test.sh
@@ -966,63 +966,6 @@
            || fail "Failed to run //a:starlark_output_dir_test with remote execution"
 }
 
-function generate_empty_treeartifact_build() {
-  mkdir -p a
-  cat > a/BUILD <<'EOF'
-load(":output_dir.bzl", "gen_output_dir")
-gen_output_dir(
-    name = "output-dir",
-    outdir = "dir",
-)
-EOF
-  cat > a/output_dir.bzl <<'EOF'
-def _gen_output_dir_impl(ctx):
-    output_dir = ctx.actions.declare_directory(ctx.attr.outdir)
-    ctx.actions.run_shell(
-        outputs = [output_dir],
-        inputs = [],
-        command = "",
-        arguments = [output_dir.path],
-    )
-    return [
-        DefaultInfo(files = depset(direct = [output_dir])),
-    ]
-
-gen_output_dir = rule(
-    implementation = _gen_output_dir_impl,
-    attrs = {
-        "outdir": attr.string(mandatory = True),
-    },
-)
-EOF
-}
-
-function test_empty_treeartifact_works_with_remote_execution() {
-  # Test that empty tree artifact works with remote execution
-  generate_empty_treeartifact_build
-
-  bazel build \
-    --remote_executor=grpc://localhost:${worker_port} \
-    //a:output-dir >& $TEST_log || fail "Failed to build"
-}
-
-function test_empty_treeartifact_works_with_remote_cache() {
-  # Test that empty tree artifact works with remote cache
-  generate_empty_treeartifact_build
-
-  bazel build \
-    --remote_cache=grpc://localhost:${worker_port} \
-    //a:output-dir >& $TEST_log || fail "Failed to build"
-
-  bazel clean
-
-  bazel build \
-    --remote_cache=grpc://localhost:${worker_port} \
-    //a:output-dir >& $TEST_log || fail "Failed to build"
-
-  expect_log "remote cache hit"
-}
-
 function test_downloads_minimal() {
   # Test that genrule outputs are not downloaded when using
   # --remote_download_minimal
@@ -2997,6 +2940,77 @@
   assert_equals "$expected_result" "$(cat bazel-testlogs/java/factorial/fact-test/coverage.dat)"
 }
 
+function generate_empty_tree_artifact_as_inputs() {
+  touch WORKSPACE
+  mkdir -p pkg
+
+  cat > pkg/def.bzl <<'EOF'
+def _r(ctx):
+    empty_d = ctx.actions.declare_directory("%s/empty_dir" % ctx.label.name)
+    ctx.actions.run_shell(
+        outputs = [empty_d],
+        command = "mkdir -p %s" % empty_d.path,
+    )
+    f = ctx.actions.declare_file("%s/file" % ctx.label.name)
+    ctx.actions.run_shell(
+        inputs = [empty_d],
+        outputs = [f],
+        command = "touch %s && cd %s && pwd" % (f.path, empty_d.path),
+    )
+    return [DefaultInfo(files = depset([f]))]
+
+r = rule(implementation = _r)
+EOF
+
+cat > pkg/BUILD <<'EOF'
+load(":def.bzl", "r")
+
+r(name = "a")
+EOF
+}
+
+function test_empty_tree_artifact_as_inputs() {
+  # Test that when an empty tree artifact is the input, an empty directory is
+  # created in the remote executor for action to read.
+  generate_empty_tree_artifact_as_inputs
+
+  bazel build \
+    --spawn_strategy=remote \
+    --remote_executor=grpc://localhost:${worker_port} \
+    //pkg:a &>$TEST_log || fail "expected build to succeed"
+
+  bazel clean --expunge
+  bazel build \
+    --spawn_strategy=remote \
+    --remote_executor=grpc://localhost:${worker_port} \
+    --experimental_remote_merkle_tree_cache \
+    //pkg:a &>$TEST_log || fail "expected build to succeed with Merkle tree cache"
+
+  bazel clean --expunge
+  bazel build \
+    --spawn_strategy=remote \
+    --remote_executor=grpc://localhost:${worker_port} \
+    --experimental_sibling_repository_layout \
+    //pkg:a &>$TEST_log || fail "expected build to succeed with sibling repository layout"
+}
+
+function test_empty_tree_artifact_as_inputs_remote_cache() {
+  # Test that when empty tree artifact works for remote cache.
+  generate_empty_tree_artifact_as_inputs
+
+  bazel build \
+    --remote_cache=grpc://localhost:${worker_port} \
+    //pkg:a &>$TEST_log || fail "expected build to succeed"
+
+  bazel clean
+
+  bazel build \
+    --remote_cache=grpc://localhost:${worker_port} \
+    //pkg:a &>$TEST_log || fail "expected build to succeed"
+
+  expect_log "remote cache hit"
+}
+
 # Runs coverage with `cc_test` and RE then checks the coverage file is returned.
 # Older versions of gcov are not supported with bazel coverage and so will be skipped.
 # See the above `test_java_rbe_coverage_produces_report` for more information.