Index: lldb/include/lldb/Host/common/NativeProcessProtocol.h
===================================================================
--- lldb/include/lldb/Host/common/NativeProcessProtocol.h
+++ lldb/include/lldb/Host/common/NativeProcessProtocol.h
@@ -30,6 +30,8 @@
 #include <vector>
 
 namespace lldb_private {
+LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
+
 class MemoryRegionInfo;
 class ResumeActionList;
 
@@ -228,6 +230,15 @@
   virtual Status GetFileLoadAddress(const llvm::StringRef &file_name,
                                     lldb::addr_t &load_addr) = 0;
 
+  /// Extension flag constants, returned by Factory::GetSupportedExtensions()
+  /// and passed to SetEnabledExtension()
+  enum class Extension {
+    fork = (1u << 0),
+    vfork = (1u << 1),
+
+    LLVM_MARK_AS_BITMASK_ENUM(vfork)
+  };
+
   class Factory {
   public:
     virtual ~Factory();
@@ -274,6 +285,12 @@
     virtual llvm::Expected<std::unique_ptr<NativeProcessProtocol>>
     Attach(lldb::pid_t pid, NativeDelegate &native_delegate,
            MainLoop &mainloop) const = 0;
+
+    /// Get the bitmask of extensions supported by this process plugin.
+    ///
+    /// \return
+    ///     A NativeProcessProtocol::Extension bitmask.
+    virtual Extension GetSupportedExtensions() const { return {}; }
   };
 
   /// Start tracing a process or its threads.
@@ -328,6 +345,15 @@
     return llvm::make_error<UnimplementedError>();
   }
 
+  /// Method called in order to propagate the bitmap of protocol
+  /// extensions supported by the client.
+  ///
+  /// \param[in] flags
+  ///     The bitmap of enabled extensions.
+  virtual void SetEnabledExtensions(Extension flags) {
+    m_enabled_extensions = flags;
+  }
+
 protected:
   struct SoftwareBreakpoint {
     uint32_t ref_count;
@@ -357,6 +383,9 @@
   // stopping it.
   llvm::DenseSet<int> m_signals_to_ignore;
 
+  // Extensions enabled per the last SetEnabledExtensions() call.
+  Extension m_enabled_extensions;
+
   // lldb_private::Host calls should be used to launch a process for debugging,
   // and then the process should be attached to. When attaching to a process
   // lldb_private::Host calls should be used to locate the process to attach
Index: lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py
===================================================================
--- lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py
+++ lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py
@@ -854,6 +854,8 @@
         "qEcho",
         "QPassSignals",
         "multiprocess",
+        "fork-events",
+        "vfork-events",
     ]
 
     def parse_qSupported_response(self, context):
Index: lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h
===================================================================
--- lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h
+++ lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h
@@ -103,6 +103,8 @@
   bool m_thread_suffix_supported = false;
   bool m_list_threads_in_stop_reply = false;
 
+  NativeProcessProtocol::Extension m_extensions_supported = {};
+
   PacketResult SendONotification(const char *buffer, uint32_t len);
 
   PacketResult SendWResponse(NativeProcessProtocol *process);
@@ -264,6 +266,9 @@
   llvm::Expected<lldb::tid_t> ReadTid(StringExtractorGDBRemote &packet,
                                       bool allow_all, lldb::pid_t default_pid);
 
+  // Call SetEnabledExtensions() with appropriate flags on the process.
+  void SetEnabledExtensions(NativeProcessProtocol &process);
+
   // For GDBRemoteCommunicationServerLLGS only
   GDBRemoteCommunicationServerLLGS(const GDBRemoteCommunicationServerLLGS &) =
       delete;
Index: lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
===================================================================
--- lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
+++ lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
@@ -259,6 +259,8 @@
     m_continue_process = m_current_process = m_debugged_process_up.get();
   }
 
+  SetEnabledExtensions(*m_current_process);
+
   // Handle mirroring of inferior stdout/stderr over the gdb-remote protocol as
   // needed. llgs local-process debugging may specify PTY paths, which will
   // make these file actions non-null process launch -i/e/o will also make
@@ -327,6 +329,7 @@
   }
   m_debugged_process_up = std::move(*process_or);
   m_continue_process = m_current_process = m_debugged_process_up.get();
+  SetEnabledExtensions(*m_current_process);
 
   // Setup stdout/stderr mapping from inferior.
   auto terminal_fd = m_debugged_process_up->GetTerminalFileDescriptor();
@@ -3557,7 +3560,7 @@
 
 std::vector<std::string> GDBRemoteCommunicationServerLLGS::HandleFeatures(
     const llvm::ArrayRef<llvm::StringRef> client_features) {
-  auto ret =
+  std::vector<std::string> ret =
       GDBRemoteCommunicationServerCommon::HandleFeatures(client_features);
   ret.insert(ret.end(), {
     "QThreadSuffixSupported+", "QListThreadsInStopReply+",
@@ -3566,5 +3569,36 @@
         "QPassSignals+", "qXfer:auxv:read+", "qXfer:libraries-svr4:read+",
 #endif
   });
+
+  // check for client features
+  using Extension = NativeProcessProtocol::Extension;
+  m_extensions_supported = {};
+  for (llvm::StringRef x : client_features)
+    m_extensions_supported |= llvm::StringSwitch<Extension>(x)
+                                  .Case("fork-events+", Extension::fork)
+                                  .Case("vfork-events+", Extension::vfork)
+                                  .Default({});
+  m_extensions_supported &= m_process_factory.GetSupportedExtensions();
+
+  // report only if actually supported
+  if (bool(m_extensions_supported & NativeProcessProtocol::Extension::fork))
+    ret.push_back("fork-events+");
+  if (bool(m_extensions_supported & NativeProcessProtocol::Extension::vfork))
+    ret.push_back("vfork-events+");
+
+  if (m_debugged_process_up)
+    SetEnabledExtensions(*m_debugged_process_up);
   return ret;
 }
+
+void GDBRemoteCommunicationServerLLGS::SetEnabledExtensions(
+    NativeProcessProtocol &process) {
+  NativeProcessProtocol::Extension flags = {};
+  if (bool(m_extensions_supported & NativeProcessProtocol::Extension::fork))
+    flags |= NativeProcessProtocol::Extension::fork;
+  if (bool(m_extensions_supported & NativeProcessProtocol::Extension::vfork))
+    flags |= NativeProcessProtocol::Extension::vfork;
+
+  assert(!bool(flags & ~m_process_factory.GetSupportedExtensions()));
+  process.SetEnabledExtensions(flags);
+}