diff --git a/lldb/include/lldb/API/SBTarget.h b/lldb/include/lldb/API/SBTarget.h
index a50e791d4fe3c2..1db54279fcb596 100644
--- a/lldb/include/lldb/API/SBTarget.h
+++ b/lldb/include/lldb/API/SBTarget.h
@@ -127,7 +127,9 @@ class LLDB_API SBTarget {
   ///     The argument array.
   ///
   /// \param[in] envp
-  ///     The environment array.
+  ///     The environment array. If this is null, the default
+  ///     environment values (provided through `settings set
+  ///     target.env-vars`) will be used.
   ///
   /// \param[in] stdin_path
   ///     The path to use when re-directing the STDIN of the new
@@ -175,7 +177,9 @@ class LLDB_API SBTarget {
   ///     The argument array.
   ///
   /// \param[in] envp
-  ///     The environment array.
+  ///     The environment array. If this isn't provided, the default
+  ///     environment values (provided through `settings set
+  ///     target.env-vars`) will be used.
   ///
   /// \param[in] working_directory
   ///     The working directory to have the child process run in
diff --git a/lldb/source/API/SBTarget.cpp b/lldb/source/API/SBTarget.cpp
index b90e77280d24c9..a70f54135e0265 100644
--- a/lldb/source/API/SBTarget.cpp
+++ b/lldb/source/API/SBTarget.cpp
@@ -371,10 +371,19 @@ SBProcess SBTarget::Launch(SBListener &listener, char const **argv,
     Module *exe_module = target_sp->GetExecutableModulePointer();
     if (exe_module)
       launch_info.SetExecutableFile(exe_module->GetPlatformFileSpec(), true);
-    if (argv)
+    if (argv) {
       launch_info.GetArguments().AppendArguments(argv);
-    if (envp)
+    } else {
+      auto default_launch_info = target_sp->GetProcessLaunchInfo();
+      launch_info.GetArguments().AppendArguments(
+          default_launch_info.GetArguments());
+    }
+    if (envp) {
       launch_info.GetEnvironment() = Environment(envp);
+    } else {
+      auto default_launch_info = target_sp->GetProcessLaunchInfo();
+      launch_info.GetEnvironment() = default_launch_info.GetEnvironment();
+    }
 
     if (listener.IsValid())
       launch_info.SetListener(listener.GetSP());
diff --git a/lldb/test/API/commands/settings/TestSettings.py b/lldb/test/API/commands/settings/TestSettings.py
index 6ec59bbe7a0959..b203f85de9fb3f 100644
--- a/lldb/test/API/commands/settings/TestSettings.py
+++ b/lldb/test/API/commands/settings/TestSettings.py
@@ -204,10 +204,15 @@ def test_disassembler_settings(self):
 
     @skipIfDarwinEmbedded   # <rdar://problem/34446098> debugserver on ios etc can't write files
     def test_run_args_and_env_vars(self):
+        self.do_test_run_args_and_env_vars(use_launchsimple=False)
+
+    @skipIfDarwinEmbedded   # <rdar://problem/34446098> debugserver on ios etc can't write files
+    def test_launchsimple_args_and_env_vars(self):
+        self.do_test_run_args_and_env_vars(use_launchsimple=True)
+
+    def do_test_run_args_and_env_vars(self, use_launchsimple):
         """Test that run-args and env-vars are passed to the launched process."""
         self.build()
-        exe = self.getBuildArtifact("a.out")
-        self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 
         # Set the run-args and the env-vars.
         # And add hooks to restore the settings during tearDown().
@@ -218,7 +223,11 @@ def test_run_args_and_env_vars(self):
         self.addTearDownHook(
             lambda: self.runCmd("settings clear target.env-vars"))
 
-        launch_info = self.dbg.GetTargetAtIndex(0).GetLaunchInfo()
+        exe = self.getBuildArtifact("a.out")
+        self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+
+        target = self.dbg.GetTargetAtIndex(0)
+        launch_info = target.GetLaunchInfo()
         found_env_var = False
         for i in range(0, launch_info.GetNumEnvironmentEntries()):
             if launch_info.GetEnvironmentEntryAtIndex(i) == "MY_ENV_VAR=YES":
@@ -227,7 +236,12 @@ def test_run_args_and_env_vars(self):
         self.assertTrue(found_env_var,
                         "MY_ENV_VAR was not set in LunchInfo object")
 
-        self.runCmd("process launch --working-dir '{0}'".format(self.get_process_working_directory()),
+        wd = self.get_process_working_directory()
+        if use_launchsimple:
+            process = target.LaunchSimple(None, None, wd)
+            self.assertTrue(process)
+        else:
+            self.runCmd("process launch --working-dir '{0}'".format(wd),
                 RUN_SUCCEEDED)
 
         # Read the output file produced by running the program.