diff --git a/modules/audio_processing/aec_dump/aec_dump_impl.cc b/modules/audio_processing/aec_dump/aec_dump_impl.cc
index a915222..e4ee872 100644
--- a/modules/audio_processing/aec_dump/aec_dump_impl.cc
+++ b/modules/audio_processing/aec_dump/aec_dump_impl.cc
@@ -192,6 +192,11 @@
       // Runtime AGC1 compression gain is ignored.
       // TODO(http://bugs.webrtc.org/10432): Store compression gain in aecdumps.
       break;
+    case AudioProcessing::RuntimeSetting::Type::kCaptureFixedPostGain:
+      float x;
+      runtime_setting.GetFloat(&x);
+      setting->set_capture_fixed_post_gain(x);
+      break;
     case AudioProcessing::RuntimeSetting::Type::kNotSpecified:
       RTC_NOTREACHED();
       break;
diff --git a/modules/audio_processing/audio_processing_impl.cc b/modules/audio_processing/audio_processing_impl.cc
index 6950623..a796ed6 100644
--- a/modules/audio_processing/audio_processing_impl.cc
+++ b/modules/audio_processing/audio_processing_impl.cc
@@ -187,8 +187,7 @@
   changed |= (noise_suppressor_enabled != noise_suppressor_enabled_);
   changed |=
       (adaptive_gain_controller_enabled != adaptive_gain_controller_enabled_);
-  changed |=
-      (gain_controller2_enabled != gain_controller2_enabled_);
+  changed |= (gain_controller2_enabled != gain_controller2_enabled_);
   changed |= (pre_amplifier_enabled_ != pre_amplifier_enabled);
   changed |= (echo_controller_enabled != echo_controller_enabled_);
   changed |= (level_estimator_enabled != level_estimator_enabled_);
@@ -858,6 +857,7 @@
       return;
     case RuntimeSetting::Type::kCapturePreGain:
     case RuntimeSetting::Type::kCaptureCompressionGain:
+    case RuntimeSetting::Type::kCaptureFixedPostGain:
       capture_runtime_settings_enqueuer_.Enqueue(setting);
       return;
   }
@@ -993,6 +993,16 @@
         RTC_DCHECK_EQ(kNoError, error);
         break;
       }
+      case RuntimeSetting::Type::kCaptureFixedPostGain: {
+        if (config_.gain_controller2.enabled) {
+          float value;
+          setting.GetFloat(&value);
+          config_.gain_controller2.fixed_digital.gain_db = value;
+          private_submodules_->gain_controller2->ApplyConfig(
+              config_.gain_controller2);
+        }
+        break;
+      }
       case RuntimeSetting::Type::kCustomRenderProcessingRuntimeSetting:
         RTC_NOTREACHED();
         break;
@@ -1017,6 +1027,7 @@
         break;
       case RuntimeSetting::Type::kCapturePreGain:          // fall-through
       case RuntimeSetting::Type::kCaptureCompressionGain:  // fall-through
+      case RuntimeSetting::Type::kCaptureFixedPostGain:    // fall-through
       case RuntimeSetting::Type::kNotSpecified:
         RTC_NOTREACHED();
         break;
diff --git a/modules/audio_processing/audio_processing_unittest.cc b/modules/audio_processing/audio_processing_unittest.cc
index ec2c58b..7015042 100644
--- a/modules/audio_processing/audio_processing_unittest.cc
+++ b/modules/audio_processing/audio_processing_unittest.cc
@@ -2349,6 +2349,21 @@
 #endif
 }
 
+TEST(RuntimeSettingTest, TestCaptureFixedPostGain) {
+  using Type = AudioProcessing::RuntimeSetting::Type;
+  {
+    auto s = AudioProcessing::RuntimeSetting::CreateCaptureFixedPostGain(1.25f);
+    EXPECT_EQ(Type::kCaptureFixedPostGain, s.type());
+    float v;
+    s.GetFloat(&v);
+    EXPECT_EQ(1.25f, v);
+  }
+
+#if RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
+  EXPECT_DEATH(AudioProcessing::RuntimeSetting::CreateCapturePreGain(0.1f), "");
+#endif
+}
+
 TEST(RuntimeSettingTest, TestUsageWithSwapQueue) {
   SwapQueue<AudioProcessing::RuntimeSetting> q(1);
   auto s = AudioProcessing::RuntimeSetting();
diff --git a/modules/audio_processing/debug.proto b/modules/audio_processing/debug.proto
index 40bd5d5..2af7c81 100644
--- a/modules/audio_processing/debug.proto
+++ b/modules/audio_processing/debug.proto
@@ -83,6 +83,7 @@
 message RuntimeSetting {
   optional float capture_pre_gain = 1;
   optional float custom_render_processing_setting = 2;
+  optional float capture_fixed_post_gain = 3;
 }
 
 message Event {
diff --git a/modules/audio_processing/include/audio_processing.h b/modules/audio_processing/include/audio_processing.h
index 1d421f5..4477e81 100644
--- a/modules/audio_processing/include/audio_processing.h
+++ b/modules/audio_processing/include/audio_processing.h
@@ -391,6 +391,7 @@
       kNotSpecified,
       kCapturePreGain,
       kCaptureCompressionGain,
+      kCaptureFixedPostGain,
       kCustomRenderProcessingRuntimeSetting
     };
 
@@ -410,6 +411,14 @@
       return {Type::kCaptureCompressionGain, static_cast<float>(gain_db)};
     }
 
+    // Corresponds to Config::GainController2::fixed_digital::gain_db, but for
+    // runtime configuration.
+    static RuntimeSetting CreateCaptureFixedPostGain(float gain_db) {
+      RTC_DCHECK_GE(gain_db, 0.f);
+      RTC_DCHECK_LE(gain_db, 90.f);
+      return {Type::kCaptureFixedPostGain, gain_db};
+    }
+
     static RuntimeSetting CreateCustomRenderSetting(float payload) {
       return {Type::kCustomRenderProcessingRuntimeSetting, payload};
     }
diff --git a/modules/audio_processing/test/aec_dump_based_simulator.cc b/modules/audio_processing/test/aec_dump_based_simulator.cc
index 0852fe0..e52dfcf 100644
--- a/modules/audio_processing/test/aec_dump_based_simulator.cc
+++ b/modules/audio_processing/test/aec_dump_based_simulator.cc
@@ -8,12 +8,13 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include "modules/audio_processing/test/aec_dump_based_simulator.h"
+
 #include <iostream>
 
 #include "absl/memory/memory.h"
 #include "modules/audio_processing/echo_cancellation_impl.h"
 #include "modules/audio_processing/echo_control_mobile_impl.h"
-#include "modules/audio_processing/test/aec_dump_based_simulator.h"
 #include "modules/audio_processing/test/protobuf_utils.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/logging.h"
@@ -393,6 +394,19 @@
       }
     }
 
+    if (settings_.use_agc2) {
+      bool enable = *settings_.use_agc2;
+      apm_config.gain_controller2.enabled = enable;
+      if (settings_.agc2_fixed_gain_db) {
+        apm_config.gain_controller2.fixed_digital.gain_db =
+            *settings_.agc2_fixed_gain_db;
+      }
+      if (settings_.use_verbose_logging) {
+        std::cout << " agc2_enabled: " << (enable ? "true" : "false")
+                  << std::endl;
+      }
+    }
+
     // TODO(peah): Add support for controlling the Experimental AGC from the
     // command line.
     if (msg.has_noise_robust_agc_enabled()) {
@@ -447,10 +461,14 @@
                               ? *settings_.use_pre_amplifier
                               : msg.pre_amplifier_enabled();
       apm_config.pre_amplifier.enabled = enable;
-      if (settings_.pre_amplifier_gain_factor) {
-        apm_config.pre_amplifier.fixed_gain_factor =
-            *settings_.pre_amplifier_gain_factor;
-      }
+    }
+
+    if (msg.has_pre_amplifier_fixed_gain_factor() ||
+        settings_.pre_amplifier_gain_factor) {
+      const float gain = settings_.pre_amplifier_gain_factor
+                             ? *settings_.pre_amplifier_gain_factor
+                             : msg.pre_amplifier_fixed_gain_factor();
+      apm_config.pre_amplifier.fixed_gain_factor = gain;
     }
 
     if (settings_.use_verbose_logging && msg.has_experiments_description() &&
@@ -550,12 +568,22 @@
 void AecDumpBasedSimulator::HandleMessage(
     const webrtc::audioproc::RuntimeSetting& msg) {
   RTC_CHECK(ap_.get());
-  // Handle capture pre-gain runtime setting only if not overridden.
-  if ((!settings_.use_pre_amplifier || !(*settings_.use_pre_amplifier)) &&
-      !settings_.pre_amplifier_gain_factor) {
-    ap_->SetRuntimeSetting(
-        AudioProcessing::RuntimeSetting::CreateCapturePreGain(
-            msg.capture_pre_gain()));
+  if (msg.has_capture_pre_gain()) {
+    // Handle capture pre-gain runtime setting only if not overridden.
+    if ((!settings_.use_pre_amplifier || *settings_.use_pre_amplifier) &&
+        !settings_.pre_amplifier_gain_factor) {
+      ap_->SetRuntimeSetting(
+          AudioProcessing::RuntimeSetting::CreateCapturePreGain(
+              msg.capture_pre_gain()));
+    }
+  } else if (msg.has_capture_fixed_post_gain()) {
+    // Handle capture fixed-post-gain runtime setting only if not overridden.
+    if ((!settings_.use_agc2 || *settings_.use_agc2) &&
+        !settings_.agc2_fixed_gain_db) {
+      ap_->SetRuntimeSetting(
+          AudioProcessing::RuntimeSetting::CreateCaptureFixedPostGain(
+              msg.capture_fixed_post_gain()));
+    }
   }
 }
 
diff --git a/modules/audio_processing/test/audio_processing_simulator.cc b/modules/audio_processing/test/audio_processing_simulator.cc
index 277b1b3..a212125 100644
--- a/modules/audio_processing/test/audio_processing_simulator.cc
+++ b/modules/audio_processing/test/audio_processing_simulator.cc
@@ -373,8 +373,10 @@
   }
   if (settings_.use_agc2) {
     apm_config.gain_controller2.enabled = *settings_.use_agc2;
-    apm_config.gain_controller2.fixed_digital.gain_db =
-        settings_.agc2_fixed_gain_db;
+    if (settings_.agc2_fixed_gain_db) {
+      apm_config.gain_controller2.fixed_digital.gain_db =
+          *settings_.agc2_fixed_gain_db;
+    }
     if (settings_.agc2_use_adaptive_gain) {
       apm_config.gain_controller2.adaptive_digital.enabled =
           *settings_.agc2_use_adaptive_gain;
diff --git a/modules/audio_processing/test/audio_processing_simulator.h b/modules/audio_processing/test/audio_processing_simulator.h
index 60ee6ea..7800afa 100644
--- a/modules/audio_processing/test/audio_processing_simulator.h
+++ b/modules/audio_processing/test/audio_processing_simulator.h
@@ -75,7 +75,7 @@
   absl::optional<bool> use_agc_limiter;
   absl::optional<int> agc_compression_gain;
   absl::optional<bool> agc2_use_adaptive_gain;
-  float agc2_fixed_gain_db;
+  absl::optional<float> agc2_fixed_gain_db;
   AudioProcessing::Config::GainController2::LevelEstimator
       agc2_adaptive_level_estimator;
   absl::optional<float> pre_amplifier_gain_factor;
diff --git a/modules/audio_processing/test/audioproc_float_impl.cc b/modules/audio_processing/test/audioproc_float_impl.cc
index f9cefce..6b94a07 100644
--- a/modules/audio_processing/test/audioproc_float_impl.cc
+++ b/modules/audio_processing/test/audioproc_float_impl.cc
@@ -8,6 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include "modules/audio_processing/test/audioproc_float_impl.h"
+
 #include <string.h>
 
 #include <iostream>
@@ -20,7 +22,6 @@
 #include "modules/audio_processing/include/audio_processing.h"
 #include "modules/audio_processing/test/aec_dump_based_simulator.h"
 #include "modules/audio_processing/test/audio_processing_simulator.h"
-#include "modules/audio_processing/test/audioproc_float_impl.h"
 #include "modules/audio_processing/test/wav_based_simulator.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/flags.h"
@@ -149,10 +150,12 @@
 WEBRTC_DEFINE_int(agc_compression_gain,
                   kParameterNotSpecifiedValue,
                   "Specify the AGC compression gain (0-90)");
-WEBRTC_DEFINE_float(agc2_enable_adaptive_gain,
+WEBRTC_DEFINE_int(agc2_enable_adaptive_gain,
+                  kParameterNotSpecifiedValue,
+                  "Activate (1) or deactivate(0) the AGC2 adaptive gain");
+WEBRTC_DEFINE_float(agc2_fixed_gain_db,
                     kParameterNotSpecifiedValue,
-                    "Activate (1) or deactivate(0) the AGC2 adaptive gain");
-WEBRTC_DEFINE_float(agc2_fixed_gain_db, 0.f, "AGC2 fixed gain (dB) to apply");
+                    "AGC2 fixed gain (dB) to apply");
 
 std::vector<std::string> GetAgc2AdaptiveLevelEstimatorNames() {
   return {"RMS", "peak"};
@@ -344,7 +347,7 @@
                         &settings.agc_compression_gain);
   SetSettingIfFlagSet(FLAG_agc2_enable_adaptive_gain,
                       &settings.agc2_use_adaptive_gain);
-  settings.agc2_fixed_gain_db = FLAG_agc2_fixed_gain_db;
+  SetSettingIfSpecified(FLAG_agc2_fixed_gain_db, &settings.agc2_fixed_gain_db);
   settings.agc2_adaptive_level_estimator =
       MapAgc2AdaptiveLevelEstimator(FLAG_agc2_adaptive_level_estimator);
   SetSettingIfSpecified(FLAG_pre_amplifier_gain_factor,
@@ -454,9 +457,8 @@
       "Error: --agc_compression_gain must be specified between 0 and 90.\n");
 
   ReportConditionalErrorAndExit(
-      settings.use_agc2 && *settings.use_agc2 &&
-          ((settings.agc2_fixed_gain_db) < 0 ||
-           (settings.agc2_fixed_gain_db) > 90),
+      settings.agc2_fixed_gain_db && ((*settings.agc2_fixed_gain_db) < 0 ||
+                                      (*settings.agc2_fixed_gain_db) > 90),
       "Error: --agc2_fixed_gain_db must be specified between 0 and 90.\n");
 
   ReportConditionalErrorAndExit(
diff --git a/modules/audio_processing/test/runtime_setting_util.cc b/modules/audio_processing/test/runtime_setting_util.cc
index 104b600..bc5f700 100644
--- a/modules/audio_processing/test/runtime_setting_util.cc
+++ b/modules/audio_processing/test/runtime_setting_util.cc
@@ -9,6 +9,7 @@
  */
 
 #include "modules/audio_processing/test/runtime_setting_util.h"
+
 #include "rtc_base/checks.h"
 
 namespace webrtc {
@@ -17,9 +18,19 @@
                           const webrtc::audioproc::RuntimeSetting& setting) {
   RTC_CHECK(apm);
   // TODO(bugs.webrtc.org/9138): Add ability to handle different types
-  // of settings. Currently only CapturePreGain is supported.
-  RTC_CHECK(setting.has_capture_pre_gain());
-  apm->SetRuntimeSetting(AudioProcessing::RuntimeSetting::CreateCapturePreGain(
-      setting.capture_pre_gain()));
+  // of settings. Currently only CapturePreGain and CaptureFixedPostGain are
+  // supported.
+  RTC_CHECK(setting.has_capture_pre_gain() ||
+            setting.has_capture_fixed_post_gain());
+
+  if (setting.has_capture_pre_gain()) {
+    apm->SetRuntimeSetting(
+        AudioProcessing::RuntimeSetting::CreateCapturePreGain(
+            setting.capture_pre_gain()));
+  } else if (setting.has_capture_fixed_post_gain()) {
+    apm->SetRuntimeSetting(
+        AudioProcessing::RuntimeSetting::CreateCaptureFixedPostGain(
+            setting.capture_fixed_post_gain()));
+  }
 }
 }  // namespace webrtc