diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index a973ffeb3a..86d5c21043 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -6,6 +6,7 @@
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
+import json
 import os
 import re
 import sys
@@ -291,6 +292,35 @@ def _CheckNoSourcesAbove(input_api, gn_files, output_api):
         items=violating_gn_files)]
   return []
 
+def _CheckNoMixingCAndCCSources(input_api, gn_files, output_api):
+  # Disallow mixing .c and .cc source files in the same target.
+  source_pattern = input_api.re.compile(r' +sources \+?= \[(.*?)\]',
+                                        re.MULTILINE | re.DOTALL)
+  file_pattern = input_api.re.compile(r'"(.*)"')
+  violating_gn_files = dict()
+  for gn_file in gn_files:
+    contents = input_api.ReadFile(gn_file)
+    for source_block_match in source_pattern.finditer(contents):
+      c_files = []
+      cc_files = []
+      for file_list_match in file_pattern.finditer(source_block_match.group(1)):
+        source_file = file_list_match.group(1)
+        if source_file.endswith('.c'):
+          c_files.append(source_file)
+        if source_file.endswith('.cc'):
+          cc_files.append(source_file)
+      if c_files and cc_files:
+        violating_gn_files[gn_file.LocalPath()] = sorted(c_files + cc_files)
+  if violating_gn_files:
+    return [output_api.PresubmitError(
+        'GN targets cannot mix .cc and .c source files. Please create a '
+        'separate target for each collection of sources.\n'
+        'Mixed sources: \n'
+        '%s\n'
+        'Violating GN files:' % json.dumps(violating_gn_files, indent=2),
+        items=violating_gn_files.keys())]
+  return []
+
 def _CheckGnChanges(input_api, output_api):
   source_file_filter = lambda x: input_api.FilterSourceFile(
       x, white_list=(r'.+\.(gn|gni)$',))
@@ -304,6 +334,7 @@ def _CheckGnChanges(input_api, output_api):
   if gn_files:
     result.extend(_CheckNoRtcBaseDeps(input_api, gn_files, output_api))
     result.extend(_CheckNoSourcesAbove(input_api, gn_files, output_api))
+    result.extend(_CheckNoMixingCAndCCSources(input_api, gn_files, output_api))
   return result
 
 def _CheckUnwantedDependencies(input_api, output_api):
diff --git a/webrtc/common_audio/BUILD.gn b/webrtc/common_audio/BUILD.gn
index 39702dc13c..5d7a9c6123 100644
--- a/webrtc/common_audio/BUILD.gn
+++ b/webrtc/common_audio/BUILD.gn
@@ -28,8 +28,6 @@ rtc_static_library("common_audio") {
     "blocker.h",
     "channel_buffer.cc",
     "channel_buffer.h",
-    "fft4g.c",
-    "fft4g.h",
     "fir_filter.cc",
     "fir_filter.h",
     "fir_filter_neon.h",
@@ -49,6 +47,65 @@ rtc_static_library("common_audio") {
     "resampler/resampler.cc",
     "resampler/sinc_resampler.cc",
     "resampler/sinc_resampler.h",
+    "smoothing_filter.cc",
+    "smoothing_filter.h",
+    "sparse_fir_filter.cc",
+    "sparse_fir_filter.h",
+    "vad/include/vad.h",
+    "vad/vad.cc",
+    "wav_file.cc",
+    "wav_file.h",
+    "wav_header.cc",
+    "wav_header.h",
+    "window_generator.cc",
+    "window_generator.h",
+  ]
+
+  deps = [
+    "../base:rtc_analytics",
+    "../system_wrappers",
+  ]
+  public_deps = [
+    ":common_audio_c",
+  ]
+
+  defines = []
+  if (rtc_use_openmax_dl) {
+    sources += [
+      "real_fourier_openmax.cc",
+      "real_fourier_openmax.h",
+    ]
+    defines += [ "RTC_USE_OPENMAX_DL" ]
+    if (rtc_build_openmax_dl) {
+      deps += [ "//third_party/openmax_dl/dl" ]
+    }
+  }
+
+  if (rtc_build_with_neon) {
+    deps += [ ":common_audio_neon" ]
+  }
+
+  if (is_win) {
+    cflags = [ "/wd4334" ]  # Ignore warning on shift operator promotion.
+  }
+
+  public_configs = [ ":common_audio_config" ]
+
+  if (!build_with_chromium && is_clang) {
+    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+    suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
+  }
+
+  if (current_cpu == "x86" || current_cpu == "x64") {
+    deps += [ ":common_audio_sse2" ]
+  }
+}
+
+rtc_source_set("common_audio_c") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+  sources = [
+    "fft4g.c",
+    "fft4g.h",
     "ring_buffer.c",
     "ring_buffer.h",
     "signal_processing/auto_corr_to_refl_coef.c",
@@ -86,13 +143,7 @@ rtc_static_library("common_audio") {
     "signal_processing/splitting_filter.c",
     "signal_processing/sqrt_of_one_minus_x_squared.c",
     "signal_processing/vector_scaling_operations.c",
-    "smoothing_filter.cc",
-    "smoothing_filter.h",
-    "sparse_fir_filter.cc",
-    "sparse_fir_filter.h",
-    "vad/include/vad.h",
     "vad/include/webrtc_vad.h",
-    "vad/vad.cc",
     "vad/vad_core.c",
     "vad/vad_core.h",
     "vad/vad_filterbank.c",
@@ -102,31 +153,8 @@ rtc_static_library("common_audio") {
     "vad/vad_sp.c",
     "vad/vad_sp.h",
     "vad/webrtc_vad.c",
-    "wav_file.cc",
-    "wav_file.h",
-    "wav_header.cc",
-    "wav_header.h",
-    "window_generator.cc",
-    "window_generator.h",
   ]
 
-  deps = [
-    "../base:rtc_analytics",
-    "../system_wrappers",
-  ]
-
-  defines = []
-  if (rtc_use_openmax_dl) {
-    sources += [
-      "real_fourier_openmax.cc",
-      "real_fourier_openmax.h",
-    ]
-    defines += [ "RTC_USE_OPENMAX_DL" ]
-    if (rtc_build_openmax_dl) {
-      deps += [ "//third_party/openmax_dl/dl" ]
-    }
-  }
-
   if (current_cpu == "arm") {
     sources += [
       "signal_processing/complex_bit_reverse_arm.S",
@@ -140,10 +168,6 @@ rtc_static_library("common_audio") {
     }
   }
 
-  if (rtc_build_with_neon) {
-    deps += [ ":common_audio_neon" ]
-  }
-
   if (current_cpu == "mipsel") {
     sources += [
       "signal_processing/complex_bit_reverse_mips.c",
@@ -176,15 +200,6 @@ rtc_static_library("common_audio") {
   }
 
   public_configs = [ ":common_audio_config" ]
-
-  if (!build_with_chromium && is_clang) {
-    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
-    suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
-  }
-
-  if (current_cpu == "x86" || current_cpu == "x64") {
-    deps += [ ":common_audio_sse2" ]
-  }
 }
 
 if (current_cpu == "x86" || current_cpu == "x64") {
@@ -210,6 +225,38 @@ if (rtc_build_with_neon) {
     sources = [
       "fir_filter_neon.cc",
       "resampler/sinc_resampler_neon.cc",
+    ]
+
+    if (current_cpu != "arm64") {
+      # Enable compilation for the NEON instruction set. This is needed
+      # since //build/config/arm.gni only enables NEON for iOS, not Android.
+      # This provides the same functionality as webrtc/build/arm_neon.gypi.
+      suppressed_configs += [ "//build/config/compiler:compiler_arm_fpu" ]
+      cflags = [ "-mfpu=neon" ]
+    }
+
+    # Disable LTO on NEON targets due to compiler bug.
+    # TODO(fdegans): Enable this. See crbug.com/408997.
+    if (rtc_use_lto) {
+      cflags -= [
+        "-flto",
+        "-ffat-lto-objects",
+      ]
+    }
+
+    if (!build_with_chromium && is_clang) {
+      # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+      suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
+    }
+
+    public_deps = [
+      ":common_audio_neon_c",
+    ]
+  }
+
+  rtc_source_set("common_audio_neon_c") {
+    visibility = [ ":*" ]  # Only targets in this file can depend on this.
+    sources = [
       "signal_processing/cross_correlation_neon.c",
       "signal_processing/downsample_fast_neon.c",
       "signal_processing/min_max_operations_neon.c",
diff --git a/webrtc/modules/audio_coding/BUILD.gn b/webrtc/modules/audio_coding/BUILD.gn
index 77a9c3e264..efbf7e051b 100644
--- a/webrtc/modules/audio_coding/BUILD.gn
+++ b/webrtc/modules/audio_coding/BUILD.gn
@@ -225,10 +225,6 @@ rtc_static_library("g711") {
     "codecs/g711/audio_decoder_pcm.h",
     "codecs/g711/audio_encoder_pcm.cc",
     "codecs/g711/audio_encoder_pcm.h",
-    "codecs/g711/g711.c",
-    "codecs/g711/g711.h",
-    "codecs/g711/g711_interface.c",
-    "codecs/g711/g711_interface.h",
   ]
 
   public_configs = [ ":g711_config" ]
@@ -237,6 +233,19 @@ rtc_static_library("g711") {
     ":audio_decoder_interface",
     ":audio_encoder_interface",
   ]
+  public_deps = [
+    ":g711_c",
+  ]
+}
+
+rtc_source_set("g711_c") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+  sources = [
+    "codecs/g711/g711.c",
+    "codecs/g711/g711.h",
+    "codecs/g711/g711_interface.c",
+    "codecs/g711/g711_interface.h",
+  ]
 }
 
 config("g722_config") {
@@ -252,11 +261,6 @@ rtc_static_library("g722") {
     "codecs/g722/audio_decoder_g722.h",
     "codecs/g722/audio_encoder_g722.cc",
     "codecs/g722/audio_encoder_g722.h",
-    "codecs/g722/g722_decode.c",
-    "codecs/g722/g722_enc_dec.h",
-    "codecs/g722/g722_encode.c",
-    "codecs/g722/g722_interface.c",
-    "codecs/g722/g722_interface.h",
   ]
 
   public_configs = [ ":g722_config" ]
@@ -265,6 +269,20 @@ rtc_static_library("g722") {
     ":audio_decoder_interface",
     ":audio_encoder_interface",
   ]
+  public_deps = [
+    ":g722_c",
+  ]
+}
+
+rtc_source_set("g722_c") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+  sources = [
+    "codecs/g722/g722_decode.c",
+    "codecs/g722/g722_enc_dec.h",
+    "codecs/g722/g722_encode.c",
+    "codecs/g722/g722_interface.c",
+    "codecs/g722/g722_interface.h",
+  ]
 }
 
 config("ilbc_config") {
@@ -276,14 +294,32 @@ config("ilbc_config") {
 
 rtc_static_library("ilbc") {
   sources = [
-    "codecs/ilbc/abs_quant.c",
-    "codecs/ilbc/abs_quant.h",
-    "codecs/ilbc/abs_quant_loop.c",
-    "codecs/ilbc/abs_quant_loop.h",
     "codecs/ilbc/audio_decoder_ilbc.cc",
     "codecs/ilbc/audio_decoder_ilbc.h",
     "codecs/ilbc/audio_encoder_ilbc.cc",
     "codecs/ilbc/audio_encoder_ilbc.h",
+  ]
+
+  public_configs = [ ":ilbc_config" ]
+
+  deps = [
+    ":audio_decoder_interface",
+    ":audio_encoder_interface",
+    "../../base:rtc_base_approved",
+    "../../common_audio",
+  ]
+  public_deps = [
+    ":ilbc_c",
+  ]
+}
+
+rtc_source_set("ilbc_c") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+  sources = [
+    "codecs/ilbc/abs_quant.c",
+    "codecs/ilbc/abs_quant.h",
+    "codecs/ilbc/abs_quant_loop.c",
+    "codecs/ilbc/abs_quant_loop.h",
     "codecs/ilbc/augmented_cb_corr.c",
     "codecs/ilbc/augmented_cb_corr.h",
     "codecs/ilbc/bw_expand.c",
@@ -424,9 +460,6 @@ rtc_static_library("ilbc") {
   public_configs = [ ":ilbc_config" ]
 
   deps = [
-    ":audio_decoder_interface",
-    ":audio_encoder_interface",
-    "../../base:rtc_base_approved",
     "../../common_audio",
   ]
 }
@@ -448,6 +481,23 @@ config("isac_config") {
 }
 
 rtc_static_library("isac") {
+  sources = [
+    "codecs/isac/main/source/audio_decoder_isac.cc",
+    "codecs/isac/main/source/audio_encoder_isac.cc",
+  ]
+
+  deps = [
+    ":audio_decoder_interface",
+    ":audio_encoder_interface",
+    ":isac_common",
+  ]
+  public_deps = [
+    ":isac_c",
+  ]
+}
+
+rtc_static_library("isac_c") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
   sources = [
     "codecs/isac/main/include/audio_decoder_isac.h",
     "codecs/isac/main/include/audio_encoder_isac.h",
@@ -456,8 +506,6 @@ rtc_static_library("isac") {
     "codecs/isac/main/source/arith_routines.h",
     "codecs/isac/main/source/arith_routines_hist.c",
     "codecs/isac/main/source/arith_routines_logist.c",
-    "codecs/isac/main/source/audio_decoder_isac.cc",
-    "codecs/isac/main/source/audio_encoder_isac.cc",
     "codecs/isac/main/source/bandwidth_estimator.c",
     "codecs/isac/main/source/bandwidth_estimator.h",
     "codecs/isac/main/source/codec.h",
@@ -512,9 +560,6 @@ rtc_static_library("isac") {
   public_configs = [ ":isac_config" ]
 
   deps = [
-    ":audio_decoder_interface",
-    ":audio_encoder_interface",
-    ":isac_common",
     "../..:webrtc_common",
     "../../base:rtc_base_approved",
     "../../common_audio",
@@ -529,6 +574,31 @@ config("isac_fix_config") {
 }
 
 rtc_static_library("isac_fix") {
+  sources = [
+    "codecs/isac/fix/source/audio_decoder_isacfix.cc",
+    "codecs/isac/fix/source/audio_encoder_isacfix.cc",
+  ]
+
+  public_configs = [ ":isac_fix_config" ]
+
+  deps = [
+    ":audio_decoder_interface",
+    ":audio_encoder_interface",
+    ":isac_common",
+    "../../common_audio",
+    "../../system_wrappers",
+  ]
+  public_deps = [
+    ":isac_fix_c",
+  ]
+
+  if (rtc_build_with_neon) {
+    deps += [ ":isac_neon" ]
+  }
+}
+
+rtc_source_set("isac_fix_c") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
   sources = [
     "codecs/isac/fix/include/audio_decoder_isacfix.h",
     "codecs/isac/fix/include/audio_encoder_isacfix.h",
@@ -537,8 +607,6 @@ rtc_static_library("isac_fix") {
     "codecs/isac/fix/source/arith_routines_hist.c",
     "codecs/isac/fix/source/arith_routines_logist.c",
     "codecs/isac/fix/source/arith_routins.h",
-    "codecs/isac/fix/source/audio_decoder_isacfix.cc",
-    "codecs/isac/fix/source/audio_encoder_isacfix.cc",
     "codecs/isac/fix/source/bandwidth_estimator.c",
     "codecs/isac/fix/source/bandwidth_estimator.h",
     "codecs/isac/fix/source/codec.h",
@@ -582,18 +650,6 @@ rtc_static_library("isac_fix") {
 
   public_configs = [ ":isac_fix_config" ]
 
-  deps = [
-    ":audio_decoder_interface",
-    ":audio_encoder_interface",
-    ":isac_common",
-    "../../common_audio",
-    "../../system_wrappers",
-  ]
-
-  if (rtc_build_with_neon) {
-    deps += [ ":isac_neon" ]
-  }
-
   if (current_cpu == "arm" && arm_version >= 7) {
     sources += [
       "codecs/isac/fix/source/lattice_armv7.S",
@@ -628,6 +684,10 @@ rtc_static_library("isac_fix") {
       sources -= [ "codecs/isac/fix/source/pitch_filter_c.c" ]
     }
   }
+
+  deps = [
+    "../../common_audio",
+  ]
 }
 
 if (rtc_build_with_neon) {
@@ -676,8 +736,6 @@ rtc_static_library("pcm16b") {
     "codecs/pcm16b/audio_decoder_pcm16b.h",
     "codecs/pcm16b/audio_encoder_pcm16b.cc",
     "codecs/pcm16b/audio_encoder_pcm16b.h",
-    "codecs/pcm16b/pcm16b.c",
-    "codecs/pcm16b/pcm16b.h",
   ]
 
   deps = [
@@ -685,6 +743,18 @@ rtc_static_library("pcm16b") {
     ":audio_encoder_interface",
     ":g711",
   ]
+  public_deps = [
+    ":pcm16b_c",
+  ]
+  public_configs = [ ":pcm16b_config" ]
+}
+
+rtc_source_set("pcm16b_c") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+  sources = [
+    "codecs/pcm16b/pcm16b.c",
+    "codecs/pcm16b/pcm16b.h",
+  ]
 
   public_configs = [ ":pcm16b_config" ]
 }
@@ -699,9 +769,6 @@ rtc_static_library("webrtc_opus") {
     "codecs/opus/audio_decoder_opus.h",
     "codecs/opus/audio_encoder_opus.cc",
     "codecs/opus/audio_encoder_opus.h",
-    "codecs/opus/opus_inst.h",
-    "codecs/opus/opus_interface.c",
-    "codecs/opus/opus_interface.h",
   ]
 
   deps = [
@@ -711,6 +778,9 @@ rtc_static_library("webrtc_opus") {
     "../../base:rtc_analytics",
     "../../base:rtc_base_approved",
   ]
+  public_deps = [
+    ":webrtc_opus_c",
+  ]
 
   defines = []
   if (rtc_opus_variable_complexity) {
@@ -719,6 +789,21 @@ rtc_static_library("webrtc_opus") {
     defines += [ "WEBRTC_OPUS_VARIABLE_COMPLEXITY=0" ]
   }
 
+  if (rtc_build_opus) {
+    public_deps += [ rtc_opus_dir ]
+  } else if (build_with_mozilla) {
+    include_dirs = [ getenv("DIST") + "/include/opus" ]
+  }
+}
+
+rtc_source_set("webrtc_opus_c") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+  sources = [
+    "codecs/opus/opus_inst.h",
+    "codecs/opus/opus_interface.c",
+    "codecs/opus/opus_interface.h",
+  ]
+
   if (rtc_build_opus) {
     public_deps = [
       rtc_opus_dir,
@@ -726,6 +811,10 @@ rtc_static_library("webrtc_opus") {
   } else if (build_with_mozilla) {
     include_dirs = [ getenv("DIST") + "/include/opus" ]
   }
+
+  deps = [
+    "../../base:rtc_base_approved",
+  ]
 }
 
 if (rtc_enable_protobuf) {
@@ -1568,12 +1657,18 @@ if (rtc_include_tests) {
     }
   }
 
+  rtc_source_set("isac_test_util") {
+    testonly = true
+    sources = [
+      "codecs/isac/main/util/utility.c",
+    ]
+  }
+
   rtc_executable("isac_test") {
     testonly = true
 
     sources = [
       "codecs/isac/main/test/simpleKenny.c",
-      "codecs/isac/main/util/utility.c",
     ]
 
     include_dirs = [
@@ -1584,6 +1679,7 @@ if (rtc_include_tests) {
 
     deps = [
       ":isac",
+      ":isac_test_util",
       "../../base:rtc_base_approved",
     ]
 
@@ -1620,11 +1716,11 @@ if (rtc_include_tests) {
 
     sources = [
       "codecs/isac/main/test/ReleaseTest-API/ReleaseTest-API.cc",
-      "codecs/isac/main/util/utility.c",
     ]
 
     deps = [
       ":isac",
+      ":isac_test_util",
       "../../base:rtc_base_approved",
     ]
 
@@ -1640,11 +1736,11 @@ if (rtc_include_tests) {
 
     sources = [
       "codecs/isac/main/test/SwitchingSampRate/SwitchingSampRate.cc",
-      "codecs/isac/main/util/utility.c",
     ]
 
     deps = [
       ":isac",
+      ":isac_test_util",
     ]
 
     include_dirs = [
diff --git a/webrtc/modules/audio_device/BUILD.gn b/webrtc/modules/audio_device/BUILD.gn
index 1dee9437d3..0b210dc996 100644
--- a/webrtc/modules/audio_device/BUILD.gn
+++ b/webrtc/modules/audio_device/BUILD.gn
@@ -159,10 +159,8 @@ rtc_static_library("audio_device") {
           "mac/audio_device_mac.h",
           "mac/audio_mixer_manager_mac.cc",
           "mac/audio_mixer_manager_mac.h",
-          "mac/portaudio/pa_memorybarrier.h",
-          "mac/portaudio/pa_ringbuffer.c",
-          "mac/portaudio/pa_ringbuffer.h",
         ]
+        deps += [ ":mac_portaudio" ]
         libs = [
           # Needed for CoreGraphics:
           "ApplicationServices.framework",
@@ -243,6 +241,15 @@ rtc_static_library("audio_device") {
   }
 }
 
+rtc_source_set("mac_portaudio") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+  sources = [
+    "mac/portaudio/pa_memorybarrier.h",
+    "mac/portaudio/pa_ringbuffer.c",
+    "mac/portaudio/pa_ringbuffer.h",
+  ]
+}
+
 config("mock_audio_device_config") {
   if (is_win) {
     cflags = [
diff --git a/webrtc/modules/audio_processing/BUILD.gn b/webrtc/modules/audio_processing/BUILD.gn
index 36c766798a..5ba9f3e42c 100644
--- a/webrtc/modules/audio_processing/BUILD.gn
+++ b/webrtc/modules/audio_processing/BUILD.gn
@@ -35,11 +35,6 @@ rtc_static_library("audio_processing") {
     "agc/agc_manager_direct.cc",
     "agc/agc_manager_direct.h",
     "agc/gain_map_internal.h",
-    "agc/legacy/analog_agc.c",
-    "agc/legacy/analog_agc.h",
-    "agc/legacy/digital_agc.c",
-    "agc/legacy/digital_agc.h",
-    "agc/legacy/gain_control.h",
     "agc/loudness_histogram.cc",
     "agc/loudness_histogram.h",
     "agc/utility.cc",
@@ -168,6 +163,9 @@ rtc_static_library("audio_processing") {
     "../../audio/utility:audio_frame_operations",
     "../audio_coding:isac",
   ]
+  public_deps = [
+    ":audio_processing_c",
+  ]
 
   if (apm_debug_dump) {
     defines += [ "WEBRTC_APM_DEBUG_DUMP=1" ]
@@ -198,28 +196,8 @@ rtc_static_library("audio_processing") {
 
   if (rtc_prefer_fixed_point) {
     defines += [ "WEBRTC_NS_FIXED" ]
-    sources += [
-      "ns/noise_suppression_x.c",
-      "ns/noise_suppression_x.h",
-      "ns/nsx_core.c",
-      "ns/nsx_core.h",
-      "ns/nsx_defines.h",
-    ]
-    if (current_cpu == "mipsel") {
-      sources += [ "ns/nsx_core_mips.c" ]
-    } else {
-      sources += [ "ns/nsx_core_c.c" ]
-    }
   } else {
     defines += [ "WEBRTC_NS_FLOAT" ]
-    sources += [
-      "ns/defines.h",
-      "ns/noise_suppression.c",
-      "ns/noise_suppression.h",
-      "ns/ns_core.c",
-      "ns/ns_core.h",
-      "ns/windows_private.h",
-    ]
   }
 
   if (current_cpu == "x86" || current_cpu == "x64") {
@@ -252,6 +230,47 @@ rtc_static_library("audio_processing") {
   ]
 }
 
+rtc_source_set("audio_processing_c") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+  sources = [
+    "agc/legacy/analog_agc.c",
+    "agc/legacy/analog_agc.h",
+    "agc/legacy/digital_agc.c",
+    "agc/legacy/digital_agc.h",
+    "agc/legacy/gain_control.h",
+  ]
+
+  if (rtc_prefer_fixed_point) {
+    sources += [
+      "ns/noise_suppression_x.c",
+      "ns/noise_suppression_x.h",
+      "ns/nsx_core.c",
+      "ns/nsx_core.h",
+      "ns/nsx_defines.h",
+    ]
+    if (current_cpu == "mipsel") {
+      sources += [ "ns/nsx_core_mips.c" ]
+    } else {
+      sources += [ "ns/nsx_core_c.c" ]
+    }
+  } else {
+    sources += [
+      "ns/defines.h",
+      "ns/noise_suppression.c",
+      "ns/noise_suppression.h",
+      "ns/ns_core.c",
+      "ns/ns_core.h",
+      "ns/windows_private.h",
+    ]
+  }
+
+  deps = [
+    "../../base:rtc_base_approved",
+    "../../common_audio",
+    "../../system_wrappers",
+  ]
+}
+
 if (rtc_enable_protobuf) {
   proto_library("audioproc_debug_proto") {
     sources = [
@@ -287,7 +306,6 @@ if (rtc_build_with_neon) {
     sources = [
       "aec/aec_core_neon.cc",
       "aecm/aecm_core_neon.cc",
-      "ns/nsx_core_neon.c",
       "utility/ooura_fft_neon.cc",
       "utility/ooura_fft_tables_neon_sse2.h",
     ]
@@ -312,6 +330,9 @@ if (rtc_build_with_neon) {
     deps = [
       "../../common_audio",
     ]
+    public_deps = [
+      ":audio_processing_neon_c",
+    ]
 
     if (apm_debug_dump) {
       defines = [ "WEBRTC_APM_DEBUG_DUMP=1" ]
@@ -319,6 +340,29 @@ if (rtc_build_with_neon) {
       defines = [ "WEBRTC_APM_DEBUG_DUMP=0" ]
     }
   }
+
+  rtc_static_library("audio_processing_neon_c") {
+    sources = [
+      "ns/nsx_core_neon.c",
+    ]
+
+    if (current_cpu != "arm64") {
+      # Enable compilation for the NEON instruction set. This is needed
+      # since //build/config/arm.gni only enables NEON for iOS, not Android.
+      # This provides the same functionality as webrtc/build/arm_neon.gypi.
+      suppressed_configs += [ "//build/config/compiler:compiler_arm_fpu" ]
+      cflags = [ "-mfpu=neon" ]
+    }
+
+    # Disable LTO on NEON targets due to compiler bug.
+    # TODO(fdegans): Enable this. See crbug.com/408997.
+    if (rtc_use_lto) {
+      cflags -= [
+        "-flto",
+        "-ffat-lto-objects",
+      ]
+    }
+  }
 }
 
 if (rtc_include_tests) {