diff --git a/projects/sudoers/build.sh b/projects/sudoers/build.sh
index 905450cb4..d157c9a63 100755
--- a/projects/sudoers/build.sh
+++ b/projects/sudoers/build.sh
@@ -28,7 +28,11 @@ else
     sanitizer_opts="$SANITIZER_FLAGS"
 fi
 # This is already added by --enable-fuzzer
-CFLAGS="`echo \"$CFLAGS\" | sed \"s/ -fsanitize=fuzzer-no-link//\"`"
+CFLAGS="`echo \"$CFLAGS\" | sed 's/ -fsanitize=fuzzer-no-link//'`"
+
+# Copy optimization flag to LDFLAGS for UBSan object-size check.
+OPTFLAG="`echo \"$CFLAGS\" | sed 's/^.*\(-O[^ ]\).*$/\1/'`"
+export LDFLAGS="${LDFLAGS:-}${LDFLAGS:+ }$OPTFLAG"
 
 # Build sudo with static libs and enable fuzzing targets.
 # All fuzz targets are integrated into the build process.