diff --git a/.gitignore b/.gitignore
index 35df15ca591e..bce90ca92c03 100644
--- a/.gitignore
+++ b/.gitignore
@@ -141,7 +141,7 @@ parser/html/java/translator.jar
 .settings/
 
 # Ignore the files and directory that JetBrains IDEs create.
-/.idea/
+**/.idea/
 *.iml
 
 # Android Monitor in Android Studio creates a captures/ directory.
@@ -213,6 +213,19 @@ testing/web-platform/products/
 # Android Gradle artifacts.
 mobile/android/gradle/.gradle
 
+# Android build cache
+mobile/android/**/.build-cache
+mobile/android/**/.gradle
+mobile/android/**/build
+mobile/android/**/bin
+mobile/android/**/generated
+
+# Android local.properties
+mobile/android/**\/local.properties
+
+# Android - Web extensions: manifest.json files are generated
+mobile/android/**\/manifest.json
+
 # XCode project cruft
 /*.xcodeproj/
 
diff --git a/.hgignore b/.hgignore
index fdc9913e65a6..9316aed506bd 100644
--- a/.hgignore
+++ b/.hgignore
@@ -209,6 +209,19 @@ _OPT\.OBJ/
 # Android Gradle artifacts.
 ^mobile/android/gradle/\.gradle
 
+# Android build cache
+^mobile/android/.*\/.build-cache
+^mobile/android/.*\/.gradle
+^mobile/android/.*\/build
+^mobile/android/.*\/bin
+^mobile/android/.*\/generated
+
+# Android local.properties
+^mobile/android/.*\/local.properties
+
+# Android - Web extensions: manifest.json files are generated
+^mobile/android/.*\/manifest.json
+
 # XCode project cruft
 ^[^/]*\.xcodeproj/