Same issue here after updating to Xcode 13.3: error: backend command failed due to signal 6 (use -v to see invocation) LLVM ERROR: out of memory Allocation failed Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the project and the crash backtrace. Stack dump: 0. Program arguments: /Applications/Xcode-13.3.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-frontend -frontend -c -primary-file /var/folders/7q/ywjd0rsx6zd7vqsy2pgsn_1h0000gp/T/TemporaryDirectory.Vhfg03/CardStackComponents-1.bc -embed-bitcode -target arm64-apple-ios12.2 -Xllvm -aarch64-use-tbi -Osize -disable-llvm-optzns -module-name CardStackComponents -o buck-out/gen/Libraries/uCardStackComponents/CardStackComponents#apple-swift-compile,iphoneos-arm64/CardStackComponents.o 1. Apple Swift version 5.6 (swiftlang-5.6.0.323.62 clang-1316.0.20.8) 2. Compiling with the current language version 3. Running pass 'Function Pass Manager' on module '/var/folders/7q/ywjd0rsx6zd7vqsy2pgsn_1h0000gp/T/TemporaryDirectory.Vhfg03/CardStackComponents-1.bc'. 4. Running pass 'ObjC ARC contraction' on function '@UI_USER_INTERFACE_IDIOM' For curiosity, the error doesn't happen if I build with -Onone instead of -Osize. This is not a workaround, obviously. I want to build my releases with optimization.