Index: tools/llvm-exegesis/lib/CMakeLists.txt
===================================================================
--- tools/llvm-exegesis/lib/CMakeLists.txt
+++ tools/llvm-exegesis/lib/CMakeLists.txt
@@ -18,6 +18,7 @@
   CodeGen
   Core
   ExecutionEngine
+  GlobalISel
   MC
   MCJIT
   Object
Index: tools/llvm-exegesis/lib/InMemoryAssembler.cpp
===================================================================
--- tools/llvm-exegesis/lib/InMemoryAssembler.cpp
+++ tools/llvm-exegesis/lib/InMemoryAssembler.cpp
@@ -10,6 +10,8 @@
 #include "InMemoryAssembler.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/CodeGen/GlobalISel/CallLowering.h"
+#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
@@ -139,9 +141,15 @@
       }
     }
   }
-  // Adding the Return Opcode.
+  // Insert the return code.
   const llvm::TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
-  llvm::BuildMI(MBB, DL, TII->get(TII->getReturnOpcode()));
+  if (TII->getReturnOpcode() < TII->getNumOpcodes()) {
+    llvm::BuildMI(MBB, DL, TII->get(TII->getReturnOpcode()));
+  } else {
+    llvm::MachineIRBuilder MIB(MF);
+    MIB.setMBB(*MBB);
+    MF.getSubtarget().getCallLowering()->lowerReturn(MIB, nullptr, 0);
+  }
 }
 
 namespace {
Index: unittests/tools/llvm-exegesis/ARM/CMakeLists.txt
===================================================================
--- /dev/null
+++ unittests/tools/llvm-exegesis/ARM/CMakeLists.txt
@@ -0,0 +1,20 @@
+include_directories(
+  ${LLVM_MAIN_SRC_DIR}/lib/Target/ARM
+  ${LLVM_BINARY_DIR}/lib/Target/ARM
+  ${LLVM_MAIN_SRC_DIR}/tools/llvm-exegesis/lib
+  )
+
+set(LLVM_LINK_COMPONENTS
+  MC
+  MCParser
+  Object
+  Support
+  Symbolize
+  ARM
+  )
+
+add_llvm_unittest(LLVMExegesisARMTests
+  InMemoryAssemblerTest.cpp
+  )
+target_link_libraries(LLVMExegesisARMTests PRIVATE LLVMExegesis)
+
Index: unittests/tools/llvm-exegesis/ARM/InMemoryAssemblerTest.cpp
===================================================================
--- /dev/null
+++ unittests/tools/llvm-exegesis/ARM/InMemoryAssemblerTest.cpp
@@ -0,0 +1,79 @@
+//===-- InMemoryAssemblerTest.cpp -------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "InMemoryAssembler.h"
+#include "ARMInstrInfo.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/TargetInstrInfo.h"
+#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/MC/MCInstBuilder.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include <memory>
+
+namespace exegesis {
+namespace {
+
+using llvm::MCInstBuilder;
+using testing::ElementsAre;
+
+class MachineFunctionGeneratorTest : public ::testing::Test {
+protected:
+  MachineFunctionGeneratorTest()
+      : TT("armv7-none-linux-gnueabi"), CpuName("") {}
+
+  static void SetUpTestCase() {
+    LLVMInitializeARMTargetInfo();
+    LLVMInitializeARMTargetMC();
+    LLVMInitializeARMTarget();
+    LLVMInitializeARMAsmPrinter();
+  }
+
+  std::unique_ptr<llvm::LLVMTargetMachine> createTargetMachine() {
+    std::string Error;
+    const llvm::Target *TheTarget =
+        llvm::TargetRegistry::lookupTarget(TT, Error);
+    assert(TheTarget);
+    const llvm::TargetOptions Options;
+    return std::unique_ptr<llvm::LLVMTargetMachine>(
+        static_cast<llvm::LLVMTargetMachine *>(TheTarget->createTargetMachine(
+            TT, CpuName, "", Options, llvm::Reloc::Model::Static)));
+  }
+
+private:
+  const std::string TT;
+  const std::string CpuName;
+};
+
+TEST_F(MachineFunctionGeneratorTest, JitFunction) {
+  JitFunctionContext Context(createTargetMachine());
+  JitFunction Function(std::move(Context), {});
+  ASSERT_THAT(Function.getFunctionBytes().str(),
+              ElementsAre(0x1e, 0xff, 0x2f, 0xe1));
+}
+
+TEST_F(MachineFunctionGeneratorTest, JitFunctionADDrr) {
+  JitFunctionContext Context(createTargetMachine());
+  JitFunction Function(std::move(Context), {MCInstBuilder(llvm::ARM::ADDrr)
+                                                .addReg(llvm::ARM::R0)
+                                                .addReg(llvm::ARM::R0)
+                                                .addReg(llvm::ARM::R0)
+                                                .addImm(llvm::ARMCC::AL)
+                                                .addReg(0)
+                                                .addReg(0)});
+  ASSERT_THAT(Function.getFunctionBytes().str(),
+              ElementsAre(0x00, 0x00, 0x80, 0xe0, 0x1e, 0xff, 0x2f, 0xe1));
+}
+
+} // namespace
+} // namespace exegesis
Index: unittests/tools/llvm-exegesis/CMakeLists.txt
===================================================================
--- unittests/tools/llvm-exegesis/CMakeLists.txt
+++ unittests/tools/llvm-exegesis/CMakeLists.txt
@@ -22,7 +22,8 @@
 endif()
 
 if(LLVM_TARGETS_TO_BUILD MATCHES "X86")
-  add_subdirectory(
-    X86
-  )
+  add_subdirectory(X86)
+endif()
+if(LLVM_TARGETS_TO_BUILD MATCHES "ARM")
+	add_subdirectory(ARM)
 endif()