Index: lld/test/MachO/invalid/arm64-thunk-undefined.s
===================================================================
--- /dev/null
+++ lld/test/MachO/invalid/arm64-thunk-undefined.s
@@ -0,0 +1,24 @@
+# REQUIRES: aarch64
+
+# RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %s -o %t.o
+## This shouldn't assert.
+# RUN: not %lld -arch arm64 -lSystem -o %t/thunk %t.o 2>&1 | FileCheck %s
+
+# CHECK: error: undefined symbol: _g
+
+.subsections_via_symbols
+
+.p2align 2
+
+.globl _main, _g
+
+.globl _main
+_main:
+  bl _g
+  ret
+
+_filler1:
+.space 0x4000000
+
+_filler3:
+.space 0x4000000