diff --git a/llvm/utils/gn/secondary/llvm/tools/llvm-reduce/BUILD.gn b/llvm/utils/gn/secondary/llvm/tools/llvm-reduce/BUILD.gn
index 6c9229f8669a4..48d7db78fceb3 100644
--- a/llvm/utils/gn/secondary/llvm/tools/llvm-reduce/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/tools/llvm-reduce/BUILD.gn
@@ -35,6 +35,7 @@ executable("llvm-reduce") {
     "deltas/ReduceOperands.cpp",
     "deltas/ReduceOperandsSkip.cpp",
     "deltas/ReduceOperandsToArgs.cpp",
+    "deltas/ReduceRegisterMasks.cpp",
     "deltas/ReduceRegisterUses.cpp",
     "deltas/ReduceSpecialGlobals.cpp",
     "deltas/ReduceVirtualRegisters.cpp",