diff --git a/src/main/java/com/google/devtools/build/lib/exec/AbstractSpawnStrategy.java b/src/main/java/com/google/devtools/build/lib/exec/AbstractSpawnStrategy.java
index 0504f1b..d3aaa3c 100644
--- a/src/main/java/com/google/devtools/build/lib/exec/AbstractSpawnStrategy.java
+++ b/src/main/java/com/google/devtools/build/lib/exec/AbstractSpawnStrategy.java
@@ -54,9 +54,17 @@
 
 /** Abstract common ancestor for spawn strategies implementing the common parts. */
 public abstract class AbstractSpawnStrategy implements SandboxedSpawnActionContext {
+
+  /**
+   * Last unique identifier assigned to a spawn by this strategy.
+   *
+   * <p>These identifiers must be unique per strategy within the context of a Bazel server instance
+   * to avoid cross-contamination across actions in case we perform asynchronous deletions.
+   */
+  private static final AtomicInteger execCount = new AtomicInteger();
+
   private final SpawnInputExpander spawnInputExpander;
   private final SpawnRunner spawnRunner;
-  private final AtomicInteger execCount = new AtomicInteger();
 
   public AbstractSpawnStrategy(Path execRoot, SpawnRunner spawnRunner) {
     this.spawnInputExpander = new SpawnInputExpander(execRoot, false);
diff --git a/src/main/java/com/google/devtools/build/lib/exec/SpawnRunner.java b/src/main/java/com/google/devtools/build/lib/exec/SpawnRunner.java
index c3aee0f..08dccc5 100644
--- a/src/main/java/com/google/devtools/build/lib/exec/SpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/exec/SpawnRunner.java
@@ -23,6 +23,7 @@
 import com.google.devtools.build.lib.actions.SpawnResult;
 import com.google.devtools.build.lib.actions.cache.MetadataInjector;
 import com.google.devtools.build.lib.util.io.FileOutErr;
+import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.io.IOException;
 import java.time.Duration;
@@ -241,6 +242,18 @@
   /** Returns whether this SpawnRunner supports executing the given Spawn. */
   boolean canExec(Spawn spawn);
 
-  /* Name of the SpawnRunner. */
+  /** Returns the name of the SpawnRunner. */
   String getName();
+
+  /**
+   * Removes any files or directories that this spawn runner may have put in the sandbox base.
+   *
+   * <p>It is important that this function only removes entries that may have been generated by this
+   * build, not any possible entries that a future build may generate.
+   *
+   * @param sandboxBase path to the base of the sandbox tree where the spawn runner may have created
+   *     entries
+   * @throws IOException if there are problems deleting the entries
+   */
+  default void cleanupSandboxBase(Path sandboxBase) throws IOException {}
 }
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/AbstractSandboxSpawnRunner.java b/src/main/java/com/google/devtools/build/lib/sandbox/AbstractSandboxSpawnRunner.java
index 6bccf16..2829b64 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/AbstractSandboxSpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/AbstractSandboxSpawnRunner.java
@@ -67,7 +67,7 @@
 
   @Override
   public SpawnResult exec(Spawn spawn, SpawnExecutionContext context)
-      throws ExecException, InterruptedException {
+      throws ExecException, IOException, InterruptedException {
     ActionExecutionMetadata owner = spawn.getResourceOwner();
     context.report(ProgressStatus.SCHEDULING, getName());
     try (ResourceHandle ignored =
@@ -288,4 +288,14 @@
   protected SandboxOptions getSandboxOptions() {
     return sandboxOptions;
   }
+
+  @Override
+  public void cleanupSandboxBase(Path sandboxBase) throws IOException {
+    Path root = sandboxBase.getChild(getName());
+    if (root.exists()) {
+      for (Path child : root.getDirectoryEntries()) {
+        child.deleteTree();
+      }
+    }
+  }
 }
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 d9309be..37672d6 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
@@ -321,4 +321,18 @@
       }
     }
   }
+
+  @Override
+  public void cleanupSandboxBase(Path sandboxBase) throws IOException {
+    if (inaccessibleHelperDir.exists()) {
+      inaccessibleHelperDir.chmod(0700);
+      inaccessibleHelperDir.deleteTree();
+    }
+    if (inaccessibleHelperFile.exists()) {
+      inaccessibleHelperFile.chmod(0600);
+      inaccessibleHelperFile.delete();
+    }
+
+    super.cleanupSandboxBase(sandboxBase);
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/SandboxModule.java b/src/main/java/com/google/devtools/build/lib/sandbox/SandboxModule.java
index f2e17f9..22e3079 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/SandboxModule.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/SandboxModule.java
@@ -52,6 +52,8 @@
 import java.io.File;
 import java.io.IOException;
 import java.time.Duration;
+import java.util.HashSet;
+import java.util.Set;
 import javax.annotation.Nullable;
 
 /**
@@ -59,6 +61,9 @@
  */
 public final class SandboxModule extends BlazeModule {
 
+  /** Tracks whether we are issuing the very first build within this Bazel server instance. */
+  private static boolean firstBuild = true;
+
   /** Environment for the running command. */
   private @Nullable CommandEnvironment env;
 
@@ -69,6 +74,15 @@
   private @Nullable SandboxfsProcess sandboxfsProcess;
 
   /**
+   * Collection of spawn runner instantiated during the executor setup.
+   *
+   * <p>We need this information to clean up the heavy subdirectories of the sandbox base on build
+   * completion but to avoid wiping the whole sandbox base itself, which could be problematic across
+   * builds.
+   */
+  private final Set<SpawnRunner> spawnRunners = new HashSet<>();
+
+  /**
    * Whether to remove the sandbox worker directories after a build or not. Useful for debugging
    * to inspect the state of files on failures.
    */
@@ -163,9 +177,6 @@
 
     Path mountPoint = sandboxBase.getRelative("sandboxfs");
 
-    // Ensure that each build starts with a clean sandbox base directory. Otherwise using the `id`
-    // that is provided by SpawnExecutionPolicy#getId to compute a base directory for a sandbox
-    // might result in an already existing directory.
     if (sandboxfsProcess != null) {
       if (options.sandboxDebug) {
         env.getReporter()
@@ -178,9 +189,15 @@
       sandboxfsProcess.destroy();
       sandboxfsProcess = null;
     }
-    if (sandboxBase.exists()) {
+    // SpawnExecutionPolicy#getId returns unique base directories for each sandboxed action during
+    // the life of a Bazel server instance so we don't need to worry about stale directories from
+    // previous builds. However, on the very first build of an instance of the server, we must
+    // wipe old contents to avoid reusing stale directories.
+    if (firstBuild && sandboxBase.exists()) {
+      cmdEnv.getReporter().handle(Event.info("Deleting stale sandbox base " + sandboxBase));
       sandboxBase.deleteTree();
     }
+    firstBuild = false;
 
     PathFragment sandboxfsPath = PathFragment.create(options.sandboxfsPath);
     boolean useSandboxfs;
@@ -215,6 +232,7 @@
               cmdEnv,
               new ProcessWrapperSandboxedSpawnRunner(
                   cmdEnv, sandboxBase, cmdEnv.getRuntime().getProductName(), timeoutKillDelay));
+      spawnRunners.add(spawnRunner);
       builder.addActionContext(
           new ProcessWrapperSandboxedStrategy(cmdEnv.getExecRoot(), spawnRunner));
     }
@@ -238,6 +256,7 @@
                     defaultImage,
                     timeoutKillDelay,
                     useCustomizedImages));
+        spawnRunners.add(spawnRunner);
         builder.addActionContext(
             new DockerSandboxedStrategy(cmdEnv.getExecRoot(), spawnRunner));
       }
@@ -258,6 +277,7 @@
                   timeoutKillDelay,
                   sandboxfsProcess,
                   options.sandboxfsMapSymlinkTargets));
+      spawnRunners.add(spawnRunner);
       builder.addActionContext(new LinuxSandboxedStrategy(cmdEnv.getExecRoot(), spawnRunner));
     }
 
@@ -272,6 +292,7 @@
                   timeoutKillDelay,
                   sandboxfsProcess,
                   options.sandboxfsMapSymlinkTargets));
+      spawnRunners.add(spawnRunner);
       builder.addActionContext(new DarwinSandboxedStrategy(cmdEnv.getExecRoot(), spawnRunner));
     }
 
@@ -362,6 +383,12 @@
     public boolean canExec(Spawn spawn) {
       return sandboxSpawnRunner.canExec(spawn) || fallbackSpawnRunner.canExec(spawn);
     }
+
+    @Override
+    public void cleanupSandboxBase(Path sandboxBase) throws IOException {
+      sandboxSpawnRunner.cleanupSandboxBase(sandboxBase);
+      fallbackSpawnRunner.cleanupSandboxBase(sandboxBase);
+    }
   }
 
   /**
@@ -405,10 +432,13 @@
 
     if (shouldCleanupSandboxBase) {
       try {
-        sandboxBase.deleteTree();
+        checkNotNull(sandboxBase, "shouldCleanupSandboxBase implies sandboxBase has been set");
+        for (SpawnRunner spawnRunner : spawnRunners) {
+          spawnRunner.cleanupSandboxBase(sandboxBase);
+        }
       } catch (IOException e) {
-        env.getReporter().handle(Event.warn("Failed to delete sandbox base " + sandboxBase
-            + ": " + e));
+        env.getReporter()
+            .handle(Event.warn("Failed to delete contents of sandbox " + sandboxBase + ": " + e));
       }
       shouldCleanupSandboxBase = false;
 
diff --git a/src/test/shell/bazel/bazel_sandboxing_test.sh b/src/test/shell/bazel/bazel_sandboxing_test.sh
index 72a5b45..d2fa83d 100755
--- a/src/test/shell/bazel/bazel_sandboxing_test.sh
+++ b/src/test/shell/bazel/bazel_sandboxing_test.sh
@@ -225,19 +225,6 @@
     || fail "Genrule did not produce output: examples/genrule:tools_work"
 }
 
-# Make sure that sandboxed execution doesn't accumulate files in the
-# sandbox directory.
-function test_sandbox_cleanup() {
-  bazel --batch clean &> $TEST_log \
-    || fail "bazel clean failed"
-  bazel build examples/genrule:tools_work &> $TEST_log \
-    || fail "Hermetic genrule failed: examples/genrule:tools_work"
-  bazel shutdown &> $TEST_log || fail "bazel shutdown failed"
-  if [[ -n "$(ls -A "$(bazel info output_base)/sandbox")" ]]; then
-    fail "Build left files around afterwards"
-  fi
-}
-
 # Test for #400: Linux sandboxing and relative symbolic links.
 #
 # let A = examples/genrule/symlinks/a/b/x.txt -> ../x.txt
diff --git a/src/test/shell/integration/BUILD b/src/test/shell/integration/BUILD
index 36e1a57..1d9dd96 100644
--- a/src/test/shell/integration/BUILD
+++ b/src/test/shell/integration/BUILD
@@ -549,6 +549,16 @@
     tags = ["no_windows"],
 )
 
+sh_test(
+    name = "sandboxing_test",
+    size = "large",
+    srcs = ["sandboxing_test.sh"],
+    data = [
+        ":test-deps",
+    ],
+    tags = ["no_windows"],
+)
+
 package_group(
     name = "spend_cpu_time_users",
     packages = [
diff --git a/src/test/shell/integration/sandboxing_test.sh b/src/test/shell/integration/sandboxing_test.sh
new file mode 100755
index 0000000..0542cc5
--- /dev/null
+++ b/src/test/shell/integration/sandboxing_test.sh
@@ -0,0 +1,115 @@
+#!/bin/bash
+#
+# Copyright 2019 The Bazel Authors. All rights reserved.
+#
+# 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.
+#
+# Test sandboxing spawn strategy
+#
+
+set -euo pipefail
+
+# Load the test setup defined in the parent directory
+CURRENT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "${CURRENT_DIR}/../integration_test_setup.sh" \
+  || { echo "integration_test_setup.sh not found!" >&2; exit 1; }
+
+function tear_down() {
+  bazel clean --expunge
+  bazel shutdown
+  rm -rf pkg
+}
+
+function test_sandbox_base_contents_wiped_only_on_startup() {
+  mkdir pkg
+  cat >pkg/BUILD <<EOF
+genrule(name = "pkg", outs = ["pkg.out"], cmd = "echo >\$@")
+EOF
+
+  local output_base="$(bazel info output_base)"
+
+  do_build() {
+    bazel build --genrule_strategy=sandboxed //pkg
+  }
+
+  do_build >"${TEST_log}" 2>&1 || fail "Expected build to succeed"
+  find "${output_base}" >>"${TEST_log}" 2>&1 || true
+
+  local sandbox_dir="$(echo "${output_base}/sandbox"/*-sandbox)"
+  [[ -d "${sandbox_dir}" ]] \
+    || fail "${sandbox_dir} is missing; prematurely deleted?"
+
+  local garbage="${output_base}/sandbox/garbage"
+  mkdir -p "${garbage}/some/nested/contents"
+  do_build >"${TEST_log}" 2>&1 || fail "Expected build to succeed"
+  expect_not_log "Deleting stale sandbox"
+  [[ -d "${garbage}" ]] \
+    || fail "Spurious contents deleted from sandbox base too early"
+
+  bazel shutdown
+  do_build >"${TEST_log}" 2>&1 || fail "Expected build to succeed"
+  expect_log "Deleting stale sandbox"
+  [[ ! -d "${garbage}" ]] \
+    || fail "sandbox base was not cleaned on restart"
+}
+
+function test_sandbox_base_can_be_rm_rfed() {
+  mkdir pkg
+  cat >pkg/BUILD <<EOF
+genrule(name = "pkg", outs = ["pkg.out"], cmd = "echo >\$@")
+EOF
+
+  local output_base="$(bazel info output_base)"
+
+  do_build() {
+    bazel build --genrule_strategy=sandboxed //pkg
+  }
+
+  do_build >"${TEST_log}" 2>&1 || fail "Expected build to succeed"
+  find "${output_base}" >>"${TEST_log}" 2>&1 || true
+
+  local sandbox_base="${output_base}/sandbox"
+  [[ -d "${sandbox_base}" ]] \
+    || fail "${sandbox_base} is missing; build did not use sandboxing?"
+
+  # Ensure the sandbox base does not contain protected files that would prevent
+  # a simple "rm -rf" from working under an unprivileged user.
+  rm -rf "${sandbox_base}" || fail "Cannot clean sandbox base"
+
+  # And now ensure Bazel reconstructs the sandbox base on a second build.
+  do_build >"${TEST_log}" 2>&1 || fail "Expected build to succeed"
+}
+
+function test_sandbox_old_contents_not_reused_in_consecutive_builds() {
+  mkdir pkg
+  cat >pkg/BUILD <<EOF
+genrule(
+    name = "pkg",
+    srcs = ["pkg.in"],
+    outs = ["pkg.out"],
+    cmd = "cp \$(location :pkg.in) \$@",
+)
+EOF
+  touch pkg/pkg.in
+
+  for i in $(seq 5); do
+    # Ensure that, even if we don't clean up the sandbox at all (with
+    # --sandbox_debug), consecutive builds don't step on each other by trying to
+    # reuse previous spawn identifiers.
+    bazel build --genrule_strategy=sandboxed --sandbox_debug //pkg \
+      >"${TEST_log}" 2>&1 || fail "Expected build to succeed"
+    echo foo >>pkg/pkg.in
+  done
+}
+
+run_suite "sandboxing"