--- a/mobile/android/base/Makefile.in
+++ b/mobile/android/base/Makefile.in
@@ -397,31 +397,35 @@ all_resources = \
 # All of generated/org/mozilla/gecko/R.java, gecko.ap_, and R.txt are
 # produced by aapt; this saves aapt invocations.  The trailing
 # semi-colon defines an empty recipe; defining no recipe at all causes
 # Make to treat the target differently, in a way that defeats our
 # dependencies.
 
 generated/org/mozilla/gecko/R.java: .aapt.deps ;
 
+# Only add libraries that contain resources here. We (unecessarily) generate an identical R.java which
+# is copied into each of these locations, and each of these files contains thousands of fields.
+# Each unnecessary copy therefore wastes unnecessary fields in the output dex file.
+# Note: usually proguard will help clean this up after the fact, but having too many fields will cause
+# dexing to fail, regardless of any later optimisations proguard could later make to bring us back
+# under the limit.
+# Ideally we would fix our aapt invocations to correctly generate minimal copies of R.java for each
+# package, but that seems redundant since gradle builds are able to correctly generate these files.
+
 # If native devices are enabled, add Google Play Services, build their resources
-generated/android/support/v4/R.java: .aapt.deps ;
 generated/android/support/v7/appcompat/R.java: .aapt.deps ;
 generated/android/support/v7/cardview/R.java: .aapt.deps ;
 generated/android/support/design/R.java: .aapt.deps ;
 generated/android/support/v7/mediarouter/R.java: .aapt.deps ;
 generated/android/support/v7/recyclerview/R.java: .aapt.deps ;
-generated/android/support/customtabs/R.java: .aapt.deps ;
-generated/android/support/v7/palette/R.java: .aapt.deps ;
 generated/com/google/android/gms/R.java: .aapt.deps ;
 generated/com/google/android/gms/ads/R.java: .aapt.deps ;
 generated/com/google/android/gms/base/R.java: .aapt.deps ;
 generated/com/google/android/gms/cast/R.java: .aapt.deps ;
-generated/com/google/android/gms/gcm/R.java: .aapt.deps ;
-generated/com/google/android/gms/measurement/R.java: .aapt.deps ;
 
 gecko.ap_: .aapt.deps ;
 R.txt: .aapt.deps ;
 
 # [Comment 2/3] This tom-foolery provides a target that forces a
 # rebuild of gecko.ap_.  This is used during packaging to ensure that
 # resources are fresh.  The alternative would be complicated; see
 # [Comment 1/3].

--- a/mobile/android/base/moz.build
+++ b/mobile/android/base/moz.build
@@ -57,17 +57,16 @@ resjar = add_java_jar('gecko-R')
 resjar.sources = []
 resjar.generated_sources += [
     'org/mozilla/gecko/R.java',
 ]
 
 if CONFIG['ANDROID_SUPPORT_V4_AAR']:
     ANDROID_EXTRA_PACKAGES += ['android.support.v4']
     ANDROID_EXTRA_RES_DIRS += ['%' + CONFIG['ANDROID_SUPPORT_V4_AAR_RES']]
-    resjar.generated_sources += ['android/support/v4/R.java']
 if CONFIG['ANDROID_APPCOMPAT_V7_AAR']:
     ANDROID_EXTRA_PACKAGES += ['android.support.v7.appcompat']
     ANDROID_EXTRA_RES_DIRS += ['%' + CONFIG['ANDROID_APPCOMPAT_V7_AAR_RES']]
     resjar.generated_sources += ['android/support/v7/appcompat/R.java']
 if CONFIG['ANDROID_CARDVIEW_V7_AAR']:
     ANDROID_EXTRA_PACKAGES += ['android.support.v7.cardview']
     ANDROID_EXTRA_RES_DIRS += ['%' + CONFIG['ANDROID_CARDVIEW_V7_AAR_RES']]
     resjar.generated_sources += ['android/support/v7/cardview/R.java']
@@ -77,21 +76,19 @@ if CONFIG['ANDROID_DESIGN_AAR']:
     resjar.generated_sources += ['android/support/design/R.java']
 if CONFIG['ANDROID_RECYCLERVIEW_V7_AAR']:
     ANDROID_EXTRA_PACKAGES += ['android.support.v7.recyclerview']
     ANDROID_EXTRA_RES_DIRS += ['%' + CONFIG['ANDROID_RECYCLERVIEW_V7_AAR_RES']]
     resjar.generated_sources += ['android/support/v7/recyclerview/R.java']
 if CONFIG['ANDROID_CUSTOMTABS_AAR']:
     ANDROID_EXTRA_PACKAGES += ['android.support.customtabs']
     ANDROID_EXTRA_RES_DIRS += ['%' + CONFIG['ANDROID_CUSTOMTABS_AAR_RES']]
-    resjar.generated_sources += ['android/support/customtabs/R.java']
 if CONFIG['ANDROID_PALETTE_V7_AAR']:
     ANDROID_EXTRA_PACKAGES += ['android.support.v7.palette']
     ANDROID_EXTRA_RES_DIRS += ['%' + CONFIG['ANDROID_PALETTE_V7_AAR_RES']]
-    resjar.generated_sources += ['android/support/v7/palette/R.java']
 
 
 resjar.javac_flags += ['-Xlint:all']
 
 mgjar = add_java_jar('gecko-mozglue')
 mgjar.sources += [geckoview_source_dir + 'java/org/mozilla/gecko/' + x for x in [
     'mozglue/ByteBufferInputStream.java',
     'mozglue/DirectBufferAllocator.java',
@@ -876,22 +873,20 @@ if CONFIG['MOZ_ANDROID_GCM']:
     if CONFIG['ANDROID_PLAY_SERVICES_BASEMENT_AAR']:
         ANDROID_EXTRA_PACKAGES += ['com.google.android.gms']
         ANDROID_EXTRA_RES_DIRS += ['%' + CONFIG['ANDROID_PLAY_SERVICES_BASEMENT_AAR_RES']]
         resjar.generated_sources += ['com/google/android/gms/R.java']
 
     if CONFIG['ANDROID_PLAY_SERVICES_GCM_AAR']:
         ANDROID_EXTRA_PACKAGES += ['com.google.android.gms.gcm']
         ANDROID_EXTRA_RES_DIRS += ['%' + CONFIG['ANDROID_PLAY_SERVICES_GCM_AAR_RES']]
-        resjar.generated_sources += ['com/google/android/gms/gcm/R.java']
 
     if CONFIG['ANDROID_PLAY_SERVICES_MEASUREMENT_AAR']:
         ANDROID_EXTRA_PACKAGES += ['com.google.android.gms.measurement']
         ANDROID_EXTRA_RES_DIRS += ['%' + CONFIG['ANDROID_PLAY_SERVICES_MEASUREMENT_AAR_RES']]
-        resjar.generated_sources += ['com/google/android/gms/measurement/R.java']
 
 if CONFIG['MOZ_INSTALL_TRACKING']:
     gbjar.extra_jars += [
         CONFIG['ANDROID_PLAY_SERVICES_ADS_AAR_LIB'],
         CONFIG['ANDROID_PLAY_SERVICES_BASEMENT_AAR_LIB'],
     ]
 
     if CONFIG['ANDROID_PLAY_SERVICES_ADS_AAR']: