diff --git a/test/libcxx/test/executor.py b/test/libcxx/test/executor.py
index abfedc7..492f934 100644
--- a/test/libcxx/test/executor.py
+++ b/test/libcxx/test/executor.py
@@ -6,15 +6,16 @@
 
 
 class Executor(object):
-    def run(self, exe_path, cmd, local_cwd, env=None):
+    def run(self, exe_path, cmd, local_cwd, file_deps=None, env=None):
         """Execute a command.
             Be very careful not to change shared state in this function.
             Executor objects are shared between python processes in `lit -jN`.
         Args:
-            exe_path: str:   Local path to the executable to be run
-            cmd: [str]:      subprocess.call style command
-            local_cwd: str:  Local path to the working directory
-            env: {str: str}: Environment variables to execute under
+            exe_path: str:    Local path to the executable to be run
+            cmd: [str]:       subprocess.call style command
+            local_cwd: str:   Local path to the working directory
+            file_deps: [str]: Files required by the test
+            env: {str: str}:  Environment variables to execute under
         Returns:
             out, err, exitCode
         """
@@ -25,7 +26,7 @@
     def __init__(self):
         super(LocalExecutor, self).__init__()
 
-    def run(self, exe_path, cmd=None, work_dir='.', env=None):
+    def run(self, exe_path, cmd=None, work_dir='.', file_deps=None, env=None):
         cmd = cmd or [exe_path]
         env_cmd = []
         if env:
@@ -48,10 +49,10 @@
         self.commandPrefix = commandPrefix
         self.chain = chain
 
-    def run(self, exe_path, cmd=None, work_dir='.', env=None):
+    def run(self, exe_path, cmd=None, work_dir='.', file_deps=None, env=None):
         cmd = cmd or [exe_path]
         return self.chain.run(exe_path, self.commandPrefix + cmd, work_dir,
-                              env=env)
+                              file_deps, env=env)
 
 
 class PostfixExecutor(Executor):
@@ -62,9 +63,10 @@
         self.commandPostfix = commandPostfix
         self.chain = chain
 
-    def run(self, exe_path, cmd=None, work_dir='.', env=None):
+    def run(self, exe_path, cmd=None, work_dir='.', file_deps=None, env=None):
         cmd = cmd or [exe_path]
-        return self.chain.run(cmd + self.commandPostfix, work_dir, env=env)
+        return self.chain.run(cmd + self.commandPostfix, work_dir, file_deps,
+                              env=env)
 
 
 
@@ -107,24 +109,28 @@
             # TODO: Log failure to delete?
             pass
 
-    def run(self, exe_path, cmd=None, work_dir='.', env=None):
+    def run(self, exe_path, cmd=None, work_dir='.', file_deps=None, env=None):
         target_exe_path = None
         target_cwd = None
         try:
-            target_exe_path = self.remote_temp_file()
             target_cwd = self.remote_temp_dir()
+            target_exe_path = os.path.join(target_cwd, 'libcxx_test.exe')
             if cmd:
                 # Replace exe_path with target_exe_path.
                 cmd = [c if c != exe_path else target_exe_path for c in cmd]
             else:
                 cmd = [target_exe_path]
-            self.copy_in([exe_path], [target_exe_path])
+
+            srcs = [exe_path]
+            dsts = [target_exe_path]
+            if file_deps is not None:
+                dev_paths = [os.path.join(target_cwd, os.path.basename(f))
+                             for f in file_deps]
+                srcs.extend(file_deps)
+                dsts.extend(dev_paths)
+            self.copy_in(srcs, dsts)
             return self._execute_command_remote(cmd, target_cwd, env)
-        except:
-            raise
         finally:
-            if target_exe_path:
-                self.delete_remote(target_exe_path)
             if target_cwd:
                 self.delete_remote(target_cwd)
 
diff --git a/test/libcxx/test/format.py b/test/libcxx/test/format.py
index 0a2b893..921f02b 100644
--- a/test/libcxx/test/format.py
+++ b/test/libcxx/test/format.py
@@ -114,8 +114,14 @@
             env = None
             if self.exec_env:
                 env = self.exec_env
+            # TODO: Only list actually needed files in file_deps.
+            # Right now we just mark all of the .dat files in the same
+            # directory as dependencies, but it's likely less than that. We
+            # should add a `// FILE-DEP: foo.dat` to each test to track this.
+            data_files = [os.path.join(local_cwd, f)
+                          for f in os.listdir(local_cwd) if f.endswith('.dat')]
             out, err, rc = self.executor.run(exec_path, [exec_path],
-                                             local_cwd, env)
+                                             local_cwd, data_files, env)
             if rc != 0:
                 report = libcxx.util.makeReport(cmd, out, err, rc)
                 report = "Compiled With: %s\n%s" % (compile_cmd, report)