Index: lib/Target/ARM/ARMTargetMachine.cpp
===================================================================
--- lib/Target/ARM/ARMTargetMachine.cpp
+++ lib/Target/ARM/ARMTargetMachine.cpp
@@ -74,6 +74,10 @@
 EnableGlobalMerge("arm-global-merge", cl::Hidden,
                   cl::desc("Enable the global merge pass"));
 
+static cl::opt<bool> EnableTrapUnreachable("arm-trap-unreachable",
+  cl::Hidden, cl::ZeroOrMore, cl::init(false),
+  cl::desc("Enable generating trap for unreachable"));
+
 namespace llvm {
   void initializeARMExecutionDomainFixPass(PassRegistry&);
 }
@@ -238,6 +242,9 @@
       this->Options.EABIVersion = EABI::EABI5;
   }
 
+  if (EnableTrapUnreachable)
+    this->Options.TrapUnreachable = true;
+
   initAsmInfo();
 }
 
Index: test/CodeGen/ARM/trap-unreachable.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/trap-unreachable.ll
@@ -0,0 +1,8 @@
+; RUN: llc -mtriple=thumbv7 -arm-trap-unreachable < %s | FileCheck %s
+; CHECK: .inst.n 0xdefe
+
+define void @test() #0 {
+  unreachable
+}
+
+attributes #0 = { nounwind }