diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/ConfigurationResolver.java b/src/main/java/com/google/devtools/build/lib/analysis/config/ConfigurationResolver.java
index 3e90ffa937e7b1..c275fa438a8562 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/ConfigurationResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/ConfigurationResolver.java
@@ -419,8 +419,7 @@ public static Map<String, BuildOptions> applyTransition(
     if (doesStarlarkTransition) {
       fromOptions =
           addDefaultStarlarkOptions(
-              fromOptions,
-              StarlarkTransition.getDefaultInputValues(buildSettingPackages, transition));
+              fromOptions, StarlarkTransition.getDefaultValues(buildSettingPackages, transition));
     }
 
     // TODO(bazel-team): Add safety-check that this never mutates fromOptions.
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/starlark/FunctionTransitionUtil.java b/src/main/java/com/google/devtools/build/lib/analysis/starlark/FunctionTransitionUtil.java
index 3e795c405761ae..4611892f06d41d 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/starlark/FunctionTransitionUtil.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/starlark/FunctionTransitionUtil.java
@@ -238,18 +238,28 @@ private static BuildOptions applyTransition(
       StarlarkDefinedConfigTransition starlarkTransition)
       throws EvalException {
     BuildOptions buildOptions = buildOptionsToTransition.clone();
+    // The names and values of options that are different after this transition.
     HashMap<String, Object> convertedNewValues = new HashMap<>();
     for (Map.Entry<String, Object> entry : newValues.entrySet()) {
       String optionName = entry.getKey();
       Object optionValue = entry.getValue();
 
       if (!optionName.startsWith(COMMAND_LINE_OPTION_PREFIX)) {
-        buildOptions =
-            BuildOptions.builder()
-                .merge(buildOptions)
-                .addStarlarkOption(Label.parseAbsoluteUnchecked(optionName), optionValue)
-                .build();
-        convertedNewValues.put(optionName, optionValue);
+        Object oldValue =
+            buildOptions.getStarlarkOptions().get(Label.parseAbsoluteUnchecked(optionName));
+        if ((oldValue == null && optionValue != null)
+            || (oldValue != null && optionValue == null)
+            || (oldValue != null && !oldValue.equals(optionValue))) {
+          // TODO(bazel-team): Figure out if we need to create a whole new build options every
+          // time. Can we just keep track of the running changes and actually build a new build
+          // options after this loop?
+          buildOptions =
+              BuildOptions.builder()
+                  .merge(buildOptions)
+                  .addStarlarkOption(Label.parseAbsoluteUnchecked(optionName), optionValue)
+                  .build();
+          convertedNewValues.put(optionName, optionValue);
+        }
       } else {
         optionName = optionName.substring(COMMAND_LINE_OPTION_PREFIX.length());
 
@@ -298,8 +308,15 @@ private static BuildOptions applyTransition(
           } else {
             throw Starlark.errorf("Invalid value type for option '%s'", optionName);
           }
-          field.set(options, convertedValue);
-          convertedNewValues.put(entry.getKey(), convertedValue);
+
+          Object oldValue = field.get(options);
+          if ((oldValue == null && convertedValue != null)
+              || (oldValue != null && convertedValue == null)
+              || (oldValue != null && !oldValue.equals(convertedValue))) {
+            field.set(options, convertedValue);
+            convertedNewValues.put(entry.getKey(), convertedValue);
+          }
+
         } catch (IllegalArgumentException e) {
           throw Starlark.errorf(
               "IllegalArgumentError for option '%s': %s", optionName, e.getMessage());
@@ -342,6 +359,11 @@ private static BuildOptions applyTransition(
   // makes it so that two configurations that are the same in value may hash differently.
   private static void updateOutputDirectoryNameFragment(
       Set<String> changedOptions, Map<String, OptionInfo> optionInfoMap, BuildOptions toOptions) {
+    // Return without doing anything if this transition hasn't changed any option values.
+    if (changedOptions.isEmpty()) {
+      return;
+    }
+
     CoreOptions buildConfigOptions = toOptions.get(CoreOptions.class);
     Set<String> updatedAffectedByStarlarkTransition =
         new TreeSet<>(buildConfigOptions.affectedByStarlarkTransition);
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkTransition.java b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkTransition.java
index f3e62413fa1ed3..316be455f1c753 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkTransition.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkTransition.java
@@ -391,8 +391,8 @@ private static BuildOptions unalias(
   }
 
   /**
-   * For a given transition, find all Starlark build settings that are read while applying it, then
-   * return a map of their label to their default values.
+   * For a given transition, find all Starlark build settings that are input/output while applying
+   * it, then return a map of their label to their default values.
    *
    * <p>If the build setting is referenced by an {@link com.google.devtools.build.lib.rules.Alias},
    * the returned map entry is still keyed by the alias.
@@ -402,7 +402,7 @@ private static BuildOptions unalias(
    *     build settings *written* by relevant transitions) so do not iterate over for input
    *     packages.
    */
-  public static ImmutableMap<Label, Object> getDefaultInputValues(
+  public static ImmutableMap<Label, Object> getDefaultValues(
       Map<PackageValue.Key, PackageValue> buildSettingPackages, ConfigurationTransition root)
       throws TransitionException {
     ImmutableMap.Builder<Label, Object> defaultValues = new ImmutableMap.Builder<>();
@@ -410,7 +410,8 @@ public static ImmutableMap<Label, Object> getDefaultInputValues(
         (StarlarkTransitionVisitor)
             transition -> {
               ImmutableSet<Label> settings =
-                  getRelevantStarlarkSettingsFromTransition(transition, Settings.INPUTS);
+                  getRelevantStarlarkSettingsFromTransition(
+                      transition, Settings.INPUTS_AND_OUTPUTS);
               for (Label setting : settings) {
                 defaultValues.put(
                     setting,
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/StarlarkAttrTransitionProviderTest.java b/src/test/java/com/google/devtools/build/lib/analysis/StarlarkAttrTransitionProviderTest.java
index 9e35fdea7d4edb..6c9307b56a8277 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/StarlarkAttrTransitionProviderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/StarlarkAttrTransitionProviderTest.java
@@ -1161,60 +1161,6 @@ public void testOutputDirHash_noop_emptyReturns() throws Exception {
         .isEqualTo(getCoreOptions(dep).transitionDirectoryNameFragment);
   }
 
-  // Test that a no-op starlark transition to the top level configuration results in a
-  // different configuration.
-  // TODO(bazel-team): This can be optimized. Make these the same configuration.
-  @Test
-  public void testOutputDirHash_noop_changeToDifferentStateAsTopLevel() throws Exception {
-    writeAllowlistFile();
-    scratch.file(
-        "test/transitions.bzl",
-        "def _bar_impl(settings, attr):",
-        "  return {'//test:bar': 'barsball'}",
-        "bar_transition = transition(implementation = _bar_impl, inputs = [],",
-        "  outputs = ['//test:bar'])");
-    scratch.file(
-        "test/rules.bzl",
-        "load('//myinfo:myinfo.bzl', 'MyInfo')",
-        "load('//test:transitions.bzl', 'bar_transition')",
-        "def _impl(ctx):",
-        "  return MyInfo(dep = ctx.attr.dep)",
-        "my_rule = rule(",
-        "  implementation = _impl,",
-        "  attrs = {",
-        "    'dep': attr.label(cfg = bar_transition), ",
-        "    '_allowlist_function_transition': attr.label(",
-        "        default = '//tools/allowlists/function_transition_allowlist',",
-        "    ),",
-        "  })",
-        "def _basic_impl(ctx):",
-        "  return []",
-        "string_flag = rule(",
-        "  implementation = _basic_impl,",
-        "  build_setting = config.string(flag = True),",
-        ")",
-        "simple = rule(_basic_impl)");
-    scratch.file(
-        "test/BUILD",
-        "load('//test:rules.bzl', 'my_rule', 'string_flag', 'simple')",
-        "my_rule(name = 'test', dep = ':dep')",
-        "simple(name = 'dep')",
-        "string_flag(name = 'bar', build_setting_default = '')");
-
-    // Use configuration that is same as what the transition will change.
-    useConfiguration(ImmutableMap.of("//test:bar", "barsball"));
-
-    ConfiguredTarget test = getConfiguredTarget("//test");
-
-    @SuppressWarnings("unchecked")
-    ConfiguredTarget dep =
-        Iterables.getOnlyElement(
-            (List<ConfiguredTarget>) getMyInfoFromTarget(test).getValue("dep"));
-
-    assertThat(getCoreOptions(test).transitionDirectoryNameFragment).isNull();
-    assertThat(getCoreOptions(dep).transitionDirectoryNameFragment).isNotNull();
-  }
-
   // Test that setting all starlark options back to default != null hash of top level.
   // We could set some starlark options on the command line but we don't count this as a starlark
   // transition to the command line configuration will always have a null values for
@@ -1276,58 +1222,6 @@ public void testOutputDirHash_multipleStarlarkOptionTransitions_backToDefaultCom
     assertThat(getCoreOptions(dep).transitionDirectoryNameFragment).isNotNull();
   }
 
-  // Test that setting a starlark option to default (if it was already at default) doesn't
-  // produce the same hash. This is because we do hashing  before scrubbing default values
-  // out of {@code BuildOptions}.
-  // TODO(bazel-team): This can be optimized. Make these the same configuration.
-  @Test
-  public void testOutputDirHash_multipleStarlarkOptionTransitions_backToDefault() throws Exception {
-    writeAllowlistFile();
-    scratch.file(
-        "test/transitions.bzl",
-        "def _foo_two_impl(settings, attr):",
-        "  return {'//test:foo': 'foosballerina'}",
-        "foo_two_transition = transition(implementation = _foo_two_impl, inputs = [],",
-        "  outputs = ['//test:foo'])");
-    scratch.file(
-        "test/rules.bzl",
-        "load('//myinfo:myinfo.bzl', 'MyInfo')",
-        "load('//test:transitions.bzl', 'foo_two_transition')",
-        "def _impl(ctx):",
-        "  return MyInfo(dep = ctx.attr.dep)",
-        "my_rule = rule(",
-        "  implementation = _impl,",
-        "  attrs = {",
-        "    'dep': attr.label(cfg = foo_two_transition), ",
-        "    '_allowlist_function_transition': attr.label(",
-        "        default = '//tools/allowlists/function_transition_allowlist',",
-        "    ),",
-        "  })",
-        "def _basic_impl(ctx):",
-        "  return []",
-        "string_flag = rule(",
-        "  implementation = _basic_impl,",
-        "  build_setting = config.string(flag = True),",
-        ")",
-        "simple = rule(_basic_impl)");
-    scratch.file(
-        "test/BUILD",
-        "load('//test:rules.bzl', 'my_rule', 'string_flag', 'simple')",
-        "my_rule(name = 'test', dep = ':dep')",
-        "simple(name = 'dep')",
-        "string_flag(name = 'foo', build_setting_default = 'foosballerina')");
-
-    ConfiguredTarget test = getConfiguredTarget("//test");
-
-    @SuppressWarnings("unchecked")
-    ConfiguredTarget dep =
-        Iterables.getOnlyElement(
-            (List<ConfiguredTarget>) getMyInfoFromTarget(test).getValue("dep"));
-
-    assertThat(getCoreOptions(dep).transitionDirectoryNameFragment)
-        .isNotEqualTo(getCoreOptions(test).transitionDirectoryNameFragment);
-  }
-
   /** See comment above {@link FunctionTransitionUtil#updateOutputDirectoryNameFragment} */
   // TODO(bazel-team): This can be optimized. Make these the same configuration.
   @Test
@@ -1841,6 +1735,137 @@ public void starlarkSplitTransitionRequiredFragments() throws Exception {
         .containsExactly("CppOptions");
   }
 
+  /**
+   * @param directRead if set to true, reads the output value directly from the input dict, else
+   *     just passes in the same value as a string
+   */
+  private void testNoOpTransitionLeavesSameConfig_native(boolean directRead) throws Exception {
+    writeAllowlistFile();
+    setStarlarkSemanticsOptions("--experimental_starlark_config_transitions=true");
+
+    String outputValue = directRead ? "settings['//command_line_option:test_arg']" : "['frisbee']";
+    String inputs = directRead ? "['//command_line_option:test_arg']" : "[]";
+
+    scratch.file(
+        "test/defs.bzl",
+        "load('//myinfo:myinfo.bzl', 'MyInfo')",
+        "def _transition_impl(settings, attr):",
+        "  return {'//command_line_option:test_arg': " + outputValue + "}",
+        "my_transition = transition(",
+        "  implementation = _transition_impl,",
+        "  inputs = " + inputs + ",",
+        "  outputs = ['//command_line_option:test_arg'],",
+        ")",
+        "def _impl(ctx):",
+        "  return MyInfo(dep = ctx.attr.dep)",
+        "my_rule = rule(",
+        "  implementation = _impl,",
+        "  attrs = {",
+        "    'dep': attr.label(cfg = my_transition),",
+        "    '_allowlist_function_transition': attr.label(",
+        "      default = '//tools/allowlists/function_transition_allowlist'),",
+        "  })");
+    scratch.file(
+        "test/BUILD",
+        "load('//test:defs.bzl', 'my_rule')",
+        "my_rule(name = 'test', dep = ':dep')",
+        "my_rule(name = 'dep')");
+
+    useConfiguration("--test_arg=frisbee");
+    ConfiguredTarget test = getConfiguredTarget("//test");
+
+    @SuppressWarnings("unchecked")
+    ConfiguredTarget dep =
+        Iterables.getOnlyElement(
+            (List<ConfiguredTarget>) getMyInfoFromTarget(test).getValue("dep"));
+    assertThat(getCoreOptions(test).transitionDirectoryNameFragment)
+        .isEqualTo(getCoreOptions(dep).transitionDirectoryNameFragment);
+  }
+
+  @Test
+  public void testNoOpTransitionLeavesSameConfig_native_directRead() throws Exception {
+    testNoOpTransitionLeavesSameConfig_native(true);
+  }
+
+  @Test
+  public void testNoOpTransitionLeavesSameConfig_native_setToSame() throws Exception {
+    testNoOpTransitionLeavesSameConfig_native(false);
+  }
+
+  /**
+   * @param directRead if set to true, reads the output value directly from the input dict, else
+   *     just passes in the same value as a string
+   * @param setToDefault if set to true, value getting passed through the transition is the default
+   *     value of the build settings. Internally we don't keep default values in the build settings
+   *     map inside {@link BuildOptions} so it's nice to test this separately.
+   */
+  private void testNoOpTransitionLeavesSameConfig_starlark(boolean directRead, boolean setToDefault)
+      throws Exception {
+    writeAllowlistFile();
+    setStarlarkSemanticsOptions("--experimental_starlark_config_transitions=true");
+
+    String outputValue = directRead ? "settings['//test:flag']" : "'frisbee'";
+    String inputs = directRead ? "['//test:flag']" : "[]";
+    String buildSettingsDefault = setToDefault ? "frisbee" : "waterpolo";
+
+    scratch.file(
+        "test/defs.bzl",
+        "load('//myinfo:myinfo.bzl', 'MyInfo')",
+        "def _flag_impl(ctx):",
+        "  return []",
+        "my_flag = rule(",
+        "  implementation = _flag_impl,",
+        "  build_setting = config.string(flag = True)",
+        ")",
+        "def _transition_impl(settings, attr):",
+        "  return {'//test:flag': " + outputValue + "}",
+        "my_transition = transition(",
+        "  implementation = _transition_impl,",
+        "  inputs = " + inputs + ",",
+        "  outputs = ['//test:flag'],",
+        ")",
+        "def _impl(ctx):",
+        "  return MyInfo(dep = ctx.attr.dep)",
+        "my_rule = rule(",
+        "  implementation = _impl,",
+        "  attrs = {",
+        "    'dep': attr.label(cfg = my_transition),",
+        "    '_allowlist_function_transition': attr.label(",
+        "      default = '//tools/allowlists/function_transition_allowlist'),",
+        "  })");
+    scratch.file(
+        "test/BUILD",
+        "load('//test:defs.bzl', 'my_rule', 'my_flag')",
+        "my_rule(name = 'test', dep = ':dep')",
+        "my_rule(name = 'dep')",
+        "my_flag(name = 'flag', build_setting_default = '" + buildSettingsDefault + "')");
+
+    useConfiguration(ImmutableMap.of("//test:flag", "frisbee"));
+    ConfiguredTarget test = getConfiguredTarget("//test");
+
+    @SuppressWarnings("unchecked")
+    ConfiguredTarget dep =
+        Iterables.getOnlyElement(
+            (List<ConfiguredTarget>) getMyInfoFromTarget(test).getValue("dep"));
+    assertThat(getCoreOptions(test).transitionDirectoryNameFragment)
+        .isEqualTo(getCoreOptions(dep).transitionDirectoryNameFragment);
+  }
+
+  @Test
+  public void testNoOpTransitionLeavesSameConfig_starlark_directRead() throws Exception {
+    testNoOpTransitionLeavesSameConfig_starlark(true, false);
+  }
+
+  @Test
+  public void testNoOpTransitionLeavesSameConfig_starlark_setToSame() throws Exception {
+    testNoOpTransitionLeavesSameConfig_starlark(false, false);
+  }
+
+  @Test
+  public void testNoOpTransitionLeavesSameConfig_starlark_setToDefault() throws Exception {
+    testNoOpTransitionLeavesSameConfig_starlark(false, true);
+  }
+
   @Test
   public void testOptionConversionDynamicMode() throws Exception {
     // TODO(waltl): check that dynamic_mode is parsed properly.
diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcLibraryConfiguredTargetTest.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcLibraryConfiguredTargetTest.java
index 498ec4b7fddd81..796c61d3bed53c 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcLibraryConfiguredTargetTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcLibraryConfiguredTargetTest.java
@@ -1598,12 +1598,12 @@ public void testPrecompiledFilesFromDifferentConfigs() throws Exception {
         "def _impl(settings, attr):",
         "    _ignore = (settings, attr)",
         "    return [",
-        "        {'//command_line_option:cpu': 'k8'},",
+        "        {'//command_line_option:test_arg': ['foo']},",
         "    ]",
         "cpu_transition = transition(",
         "    implementation = _impl,",
         "    inputs = [],",
-        "    outputs = ['//command_line_option:cpu'],",
+        "    outputs = ['//command_line_option:test_arg'],",
         ")",
         "def _transitioned_file_impl(ctx):",
         "    return DefaultInfo(files = depset([ctx.file.src]))",