3 files changed, 34 insertions, 8 deletions

diff --git a/lldb/tools/debugserver/source/RNBContext.cpp b/lldb/tools/debugserver/source/RNBContext.cpp
index c1319af0232..c86511c6e22 100644
--- a/lldb/tools/debugserver/source/RNBContext.cpp
+++ b/lldb/tools/debugserver/source/RNBContext.cpp
@@ -42,6 +42,25 @@ const char *RNBContext::EnvironmentAtIndex(size_t index) {
     return NULL;
 }
 
+static std::string GetEnvironmentKey(const std::string &env) {
+  std::string key = env.substr(0, env.find('='));
+  if (!key.empty() && key.back() == '=')
+    key.pop_back();
+  return key;
+}
+
+void RNBContext::PushEnvironmentIfNeeded(const char *arg) {
+  if (!arg)
+    return;
+  std::string arg_key = GetEnvironmentKey(arg);
+
+  for (const std::string &entry: m_env_vec) {
+    if (arg_key == GetEnvironmentKey(entry))
+      return;
+  }
+  m_env_vec.push_back(arg);
+}
+
 const char *RNBContext::ArgumentAtIndex(size_t index) {
   if (index < m_arg_vec.size())
     return m_arg_vec[index].c_str();
diff --git a/lldb/tools/debugserver/source/RNBContext.h b/lldb/tools/debugserver/source/RNBContext.h
index 6fe7a299573..0c649ae4100 100644
--- a/lldb/tools/debugserver/source/RNBContext.h
+++ b/lldb/tools/debugserver/source/RNBContext.h
@@ -86,6 +86,7 @@ public:
     if (arg)
       m_env_vec.push_back(arg);
   }
+  void PushEnvironmentIfNeeded(const char *arg);
   void ClearEnvironment() {
     m_env_vec.erase(m_env_vec.begin(), m_env_vec.end());
   }
diff --git a/lldb/tools/debugserver/source/debugserver.cpp b/lldb/tools/debugserver/source/debugserver.cpp
index 8291f8d32b5..7ae321ba431 100644
--- a/lldb/tools/debugserver/source/debugserver.cpp
+++ b/lldb/tools/debugserver/source/debugserver.cpp
@@ -1020,6 +1020,7 @@ int main(int argc, char *argv[]) {
   optind = 1;
 #endif
 
+  bool forward_env = false;
   while ((ch = getopt_long_only(argc, argv, short_options, g_long_options,
                                 &long_option_index)) != -1) {
     DNBLogDebug("option: ch == %c (0x%2.2x) --%s%c%s\n", ch, (uint8_t)ch,
@@ -1251,14 +1252,7 @@ int main(int argc, char *argv[]) {
       break;
 
     case 'F':
-      // Pass the current environment down to the process that gets launched
-      {
-        char **host_env = *_NSGetEnviron();
-        char *env_entry;
-        size_t i;
-        for (i = 0; (env_entry = host_env[i]) != NULL; ++i)
-          remote->Context().PushEnvironment(env_entry);
-      }
+      forward_env = true;
       break;
 
     case '2':
@@ -1420,6 +1414,18 @@ int main(int argc, char *argv[]) {
   if (start_mode == eRNBRunLoopModeExit)
     return -1;
 
+  if (forward_env || start_mode == eRNBRunLoopModeInferiorLaunching) {
+    // Pass the current environment down to the process that gets launched
+    // This happens automatically in the "launching" mode. For the rest, we
+    // only do that if the user explicitly requested this via --forward-env
+    // argument.
+    char **host_env = *_NSGetEnviron();
+    char *env_entry;
+    size_t i;
+    for (i = 0; (env_entry = host_env[i]) != NULL; ++i)
+      remote->Context().PushEnvironmentIfNeeded(env_entry);
+  }
+
   RNBRunLoopMode mode = start_mode;
   char err_str[1024] = {'\0'};