Summary: The Realm Objective-C iOS framework compiled with Xcode 8.2 weighs in at 55MB with all architecture slices and bitcode included. The same codebase compiled with Xcode 8.3 produces a binary about three times larger at 158MB, including 70MB for bitcode alone. Steps to Reproduce: With Xcode 8.2.1 and 8.3 installed: 1. git clone https://github.com/realm/realm-cocoa.git 2. cd realm-cocoa 3. git checkout v2.4.4 4. git submodule update --init --recursive 5. REALM_XCODE_VERSION=8.2.1 ./build.sh ios-dynamic 6. mv build/ios/Realm.framework Realm_Xcode821.framework 7. REALM_XCODE_VERSION=8.3 ./build.sh ios-dynamic 8. mv build/ios/Realm.framework Realm_Xcode83.framework Compare Realm_Xcode821.framework with Realm_Xcode83.framework. For example: 1. size Realm_Xcode821.framework/Realm 55M Realm_Xcode821.framework/Realm 2. size Realm_Xcode83.framework/Realm 158M Realm_Xcode83.framework/Realm And: 1. otool -l -arch arm64 Realm_Xcode821.framework/Realm > Realm_Xcode821_otool_arm64.txt 2. otool -l -arch arm64 Realm_Xcode83.framework/Realm > Realm_Xcode83_otool_arm64.txt 3. git diff --no-index Realm_Xcode821_otool_arm64.txt Realm_Xcode83_otool_arm64.txt which indicates that the __LLVM (bitcode) slice grew from 15MB to 67MB. And: 1. otool -l Realm_Xcode821.framework/Realm > Realm_Xcode821_otool.txt 2. otool -l Realm_Xcode83.framework/Realm > Realm_Xcode83_otool.txt 3. git diff --no-index Realm_Xcode821_otool.txt Realm_Xcode83_otool.txt Although there's not much difference in the outputs for that one. Expected Results: Compiling with Xcode 8.3 should produce binaries of similar size as with Xcode 8.2. Actual Results: Compiling with Xcode 8.3 produces binaries approximately three times as large as with Xcode 8.2. Regression: Describe circumstances where the problem occurs or does not occur, such as software versions and/or hardware configurations. Notes: See https://github.com/realm/realm-cocoa/issues/4785