diff --git a/site/docs/cquery.html b/site/docs/cquery.html
index 6d5ad43af4744e..5355d6e796c4ff 100644
--- a/site/docs/cquery.html
+++ b/site/docs/cquery.html
@@ -369,7 +369,7 @@ <h3> Transitions </h3>
   without the options diff.
 </p>
 
-<h3>Proto</h3>
+<h3>Protocol message output</h3>
 
 <pre>
 --output=proto
@@ -401,6 +401,58 @@ <h4>--[no]proto:include_configurations</h4>
   included as <code>rule_input</code> fields.
 </p>
 
+<h3>Formatting output with a Starlark expression</h3>
+
+<pre>
+--output=starlark
+</pre>
+
+<p>
+  This output format evaluates and prints a given
+  <a href="https://docs.bazel.build/versions/master/skylark/language.html">Starlark</a>
+  expression for each resulting target. The expression may be specified with the
+  <code>--starlark:expr</code> flag.
+</p><p>
+ The specified expression can access only the core Starlark
+ <a href="https://github.com/bazelbuild/starlark/blob/master/spec.md#built-in-constants-and-functions">
+ built-in constants and functions</a>, and a global <code>target</code>, of type
+ <a href="https://docs.bazel.build/versions/master/skylark/lib/Target.html">Target</a>.
+ Note it does <b>not</b> have access to many of the
+ additional built-in constants and functions supported for rule/macro code, such as
+ <code>glob()</code> or <code>rule()</code>
+</p>
+<h4>Examples</h4>
+
+<p>
+Print a space-separated list of the base names of all files produced by <code>//foo</code>:
+</p>
+<pre>
+  bazel cquery //foo --output=starlark \
+    --starlark:expr="' '.join([f.basename for f in target.files.to_list()])"
+</pre>
+<p>
+Print a space-separated list of the paths of all files produced by <b>rule</b> targets in
+<code>//bar</code> and its subpackages:
+</p>
+<pre>
+  bazel cquery 'kind(rule, //bar/...)' --output=starlark \
+    --starlark:expr="' '.join([f.path for f in target.files.to_list()])"
+</pre>
+<p>
+Print a list of the mnemonics of all actions registered by <code>//foo</code>.
+</p>
+<pre>
+  bazel cquery //foo --output=starlark \
+    --starlark:expr="[a.mnemonic for a in target.actions]"
+</pre>
+<p>
+Print a list of compilation outputs registered by a <code>cc_library</code> <code>//baz</code>.
+</p>
+<pre>
+  bazel cquery //baz --output=starlark \
+    --starlark:expr="[f.path for f in target.output_groups.compilation_outputs.to_list()]"
+</pre>
+
 <h2 id='compare'>cquery vs. query</h2>
 
 <p>
diff --git a/src/main/java/com/google/devtools/build/lib/query2/PostAnalysisQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/PostAnalysisQueryEnvironment.java
index 4334b595c7fafe..a0ae6d5e58de6e 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/PostAnalysisQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/PostAnalysisQueryEnvironment.java
@@ -137,7 +137,8 @@ public PostAnalysisQueryEnvironment(
           SkyframeExecutor skyframeExecutor,
           BuildConfiguration hostConfiguration,
           @Nullable TransitionFactory<Rule> trimmingTransitionFactory,
-          PackageManager packageManager);
+          PackageManager packageManager)
+          throws QueryException, InterruptedException;
 
   public abstract String getOutputFormat();
 
diff --git a/src/main/java/com/google/devtools/build/lib/query2/cquery/ConfiguredTargetQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/cquery/ConfiguredTargetQueryEnvironment.java
index 246e712fc741b3..37a82530b7eea2 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/cquery/ConfiguredTargetQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/cquery/ConfiguredTargetQueryEnvironment.java
@@ -206,7 +206,8 @@ private static ImmutableMap<String, BuildConfiguration> getTransitiveConfigurati
           SkyframeExecutor skyframeExecutor,
           BuildConfiguration hostConfiguration,
           @Nullable TransitionFactory<Rule> trimmingTransitionFactory,
-          PackageManager packageManager) {
+          PackageManager packageManager)
+          throws QueryException, InterruptedException {
     AspectResolver aspectResolver =
         cqueryOptions.aspectDeps.createResolver(packageManager, eventHandler);
     return ImmutableList.of(
@@ -247,6 +248,8 @@ private static ImmutableMap<String, BuildConfiguration> getTransitiveConfigurati
             aspectResolver,
             OutputType.JSON),
         new BuildOutputFormatterCallback(
+            eventHandler, cqueryOptions, out, skyframeExecutor, accessor),
+        new StarlarkOutputFormatterCallback(
             eventHandler, cqueryOptions, out, skyframeExecutor, accessor));
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/query2/cquery/CqueryOptions.java b/src/main/java/com/google/devtools/build/lib/query2/cquery/CqueryOptions.java
index 14aea6cb2d2b01..c8dcfc37c5403a 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/cquery/CqueryOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/cquery/CqueryOptions.java
@@ -82,4 +82,14 @@ public enum Transitions {
           "if enabled, proto output will include information about configurations. When disabled,"
               + "cquery proto output format resembles query output format.")
   public boolean protoIncludeConfigurations;
+
+  @Option(
+      name = "starlark:expr",
+      defaultValue = "str(target.label)",
+      documentationCategory = OptionDocumentationCategory.QUERY,
+      effectTags = {OptionEffectTag.TERMINAL_OUTPUT},
+      help =
+          "A Starlark expression to format each configured target in cquery's"
+              + " --output=starlark mode. The configured target is bound to 'target'.")
+  public String expr;
 }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/cquery/StarlarkOutputFormatterCallback.java b/src/main/java/com/google/devtools/build/lib/query2/cquery/StarlarkOutputFormatterCallback.java
new file mode 100644
index 00000000000000..d629aa93b1dee7
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/query2/cquery/StarlarkOutputFormatterCallback.java
@@ -0,0 +1,113 @@
+// Copyright 2020 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.
+
+package com.google.devtools.build.lib.query2.cquery;
+
+import com.google.devtools.build.lib.analysis.ConfiguredTarget;
+import com.google.devtools.build.lib.events.Event;
+import com.google.devtools.build.lib.events.ExtendedEventHandler;
+import com.google.devtools.build.lib.query2.engine.QueryEnvironment.TargetAccessor;
+import com.google.devtools.build.lib.query2.engine.QueryException;
+import com.google.devtools.build.lib.server.FailureDetails.ConfigurableQuery.Code;
+import com.google.devtools.build.lib.skyframe.SkyframeExecutor;
+import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.EvalUtils;
+import com.google.devtools.build.lib.syntax.Expression;
+import com.google.devtools.build.lib.syntax.FileOptions;
+import com.google.devtools.build.lib.syntax.Module;
+import com.google.devtools.build.lib.syntax.Mutability;
+import com.google.devtools.build.lib.syntax.ParserInput;
+import com.google.devtools.build.lib.syntax.Starlark;
+import com.google.devtools.build.lib.syntax.StarlarkFunction;
+import com.google.devtools.build.lib.syntax.StarlarkSemantics;
+import com.google.devtools.build.lib.syntax.StarlarkThread;
+import com.google.devtools.build.lib.syntax.SyntaxError;
+import java.io.OutputStream;
+
+/**
+ * Starlark output formatter for cquery results. Each configured target will result in an evaluation
+ * of the Starlark expression specified by {@code --expr}.
+ */
+public class StarlarkOutputFormatterCallback extends CqueryThreadsafeCallback {
+  private static final Object[] NO_ARGS = new Object[0];
+
+  // Starlark function with single required parameter "target", a ConfiguredTarget query result.
+  private final StarlarkFunction exprEvalFn;
+
+  StarlarkOutputFormatterCallback(
+      ExtendedEventHandler eventHandler,
+      CqueryOptions options,
+      OutputStream out,
+      SkyframeExecutor skyframeExecutor,
+      TargetAccessor<ConfiguredTarget> accessor)
+      throws QueryException, InterruptedException {
+    super(eventHandler, options, out, skyframeExecutor, accessor);
+
+    // Validate that options.expr is a pure expression (for example, that it does not attempt
+    // to escape its scope via unbalanced parens).
+    ParserInput exprParserInput = ParserInput.fromString(options.expr, "--starlark:expr");
+    try {
+      Expression.parse(exprParserInput);
+    } catch (SyntaxError.Exception ex) {
+      throw new QueryException(
+          "invalid --starlark:expr: " + ex.getMessage(), Code.STARLARK_SYNTAX_ERROR);
+    }
+
+    // Create a synthetic file that defines a function with single parameter "target",
+    // whose body is provided by the user's expression.
+    String fileBody = "def f(target): return (" + options.expr + ")\n" + "f";
+    ParserInput input = ParserInput.fromString(fileBody, "--starlark:expr");
+
+    try {
+      StarlarkThread thread =
+          new StarlarkThread(Mutability.create("foo"), StarlarkSemantics.DEFAULT);
+      this.exprEvalFn =
+          (StarlarkFunction) EvalUtils.exec(input, FileOptions.DEFAULT, Module.create(), thread);
+    } catch (SyntaxError.Exception ex) {
+      throw new QueryException(
+          "invalid --starlark:expr: " + ex.getMessage(), Code.STARLARK_SYNTAX_ERROR);
+    } catch (EvalException ex) {
+      throw new QueryException(
+          "invalid --starlark:expr: " + ex.getMessageWithStack(), Code.STARLARK_EVAL_ERROR);
+    }
+  }
+
+  @Override
+  public String getName() {
+    return "starlark";
+  }
+
+  @Override
+  public void processOutput(Iterable<ConfiguredTarget> partialResult) throws InterruptedException {
+    StarlarkThread thread =
+        new StarlarkThread(Mutability.create("cquery evaluation"), StarlarkSemantics.DEFAULT);
+    thread.setMaxExecutionSteps(500_000L);
+
+    for (ConfiguredTarget target : partialResult) {
+      try {
+        // Invoke exprEvalFn with `target` argument.
+        Object result = Starlark.fastcall(thread, this.exprEvalFn, new Object[] {target}, NO_ARGS);
+
+        addResult(Starlark.str(result));
+      } catch (EvalException ex) {
+        eventHandler.handle(
+            Event.error(
+                String.format(
+                    "Starlark evaluation error for %s: %s",
+                    target.getLabel(), ex.getMessageWithStack())));
+        continue;
+      }
+    }
+  }
+}
diff --git a/src/main/protobuf/failure_details.proto b/src/main/protobuf/failure_details.proto
index 50e29a55c6cc84..0ffaff2ff18c7f 100644
--- a/src/main/protobuf/failure_details.proto
+++ b/src/main/protobuf/failure_details.proto
@@ -816,6 +816,8 @@ message ConfigurableQuery {
     ATTRIBUTE_MISSING = 7 [(metadata) = { exit_code: 2 }];
     INCORRECT_CONFIG_ARGUMENT_ERROR = 8 [(metadata) = { exit_code: 2 }];
     TARGET_MISSING = 9 [(metadata) = { exit_code: 2 }];
+    STARLARK_SYNTAX_ERROR = 10 [(metadata) = { exit_code: 2 }];
+    STARLARK_EVAL_ERROR = 11 [(metadata) = { exit_code: 2 }];
   }
 
   Code code = 1;
diff --git a/src/test/shell/integration/configured_query_test.sh b/src/test/shell/integration/configured_query_test.sh
index bcb0e14eaa84f5..09f16da8b2dd44 100755
--- a/src/test/shell/integration/configured_query_test.sh
+++ b/src/test/shell/integration/configured_query_test.sh
@@ -810,4 +810,89 @@ EOF
   assert_equals "$(grep some_file output | wc -l | egrep -o '[0-9]+')" "1"
 }
 
+function test_starlark_output_mode() {
+  local -r pkg=$FUNCNAME
+  mkdir -p $pkg
+  cat > $pkg/BUILD <<EOF
+py_library(
+    name = "pylib",
+    srcs = ["pylib.py"],
+)
+
+py_library(
+    name = "pylibtwo",
+    srcs = ["pylibtwo.py", "pylibtwo2.py",],
+)
+EOF
+
+  bazel cquery "//$pkg:all" --output=starlark \
+    --starlark:expr="str(target.label) + '%foo'" > output \
+    2>"$TEST_log" || fail "Expected success"
+
+  assert_contains "//$pkg:pylib%foo" output
+  assert_contains "//$pkg:pylibtwo%foo" output
+
+  bazel cquery "//$pkg:all" --output=starlark \
+    --starlark:expr="str(target.label) + '%' + str(target.files.to_list()[1].is_directory)" \
+    > output 2>"$TEST_log" || fail "Expected success"
+
+  assert_contains "//$pkg:pylibtwo%False" output
+  # pylib evaluation will fail, as it has only one output file.
+  assert_contains "Starlark evaluation error for //$pkg:pylib" "$TEST_log"
+}
+
+function test_starlark_output_invalid_expression() {
+  local -r pkg=$FUNCNAME
+  mkdir -p $pkg
+  touch $pkg/BUILD
+
+  bazel cquery "//$pkg:all" --output=starlark \
+    --starlark:expr="no_symbol" \
+    > output 2>"$TEST_log" && fail "Expected failure"
+
+  assert_contains "invalid --starlark:expr: name 'no_symbol' is not defined" $TEST_log
+
+  bazel cquery "//$pkg:all" --output=starlark \
+    --starlark:expr="def foo(): return 5" \
+    > output 2>"$TEST_log" && fail "Expected failure"
+
+  assert_contains "syntax error at 'def': expected expression" $TEST_log
+}
+
+function test_starlark_output_cc_library_files() {
+  local -r pkg=$FUNCNAME
+  mkdir -p $pkg
+  cat > $pkg/BUILD <<EOF
+cc_library(
+    name = "cclib",
+    srcs = ["mylib.cc"],
+)
+EOF
+
+  bazel cquery "//$pkg:all" --output=starlark \
+    --starlark:expr="' '.join([f.basename for f in target.files.to_list()])" \
+    > output 2>"$TEST_log" || fail "Expected failure"
+
+  if "$is_windows"; then
+    assert_contains "cclib.lib" output
+  else
+    assert_contains "libcclib.a" output
+    assert_contains "libcclib.so" output
+  fi
+}
+
+function test_starlark_file_output() {
+  local -r pkg=$FUNCNAME
+  mkdir -p $pkg
+  cat > $pkg/BUILD <<EOF
+exports_files(srcs = ["foo"])
+EOF
+
+  bazel cquery "//$pkg:foo" --output=starlark \
+    --starlark:expr="'path=' + target.files.to_list()[0].path" \
+    > output 2>"$TEST_log" || fail "Expected failure"
+
+  assert_contains "^path=$pkg/foo$" output
+}
+
 run_suite "${PRODUCT_NAME} configured query tests"