diff --git a/README.md b/README.md
index 8d732c75..b9fabb2c 100644
--- a/README.md
+++ b/README.md
@@ -308,6 +308,7 @@ the Wine prefix. Removing the option will revert to the previous behavior.
 |                       | <tt>PROTON_LOG_DIR</tt>        | Output log files into the directory specified. Defaults to your home directory. |
 |                       | <tt>PROTON_DUMP_DEBUG_COMMANDS</tt> | When running a game, Proton will write some useful debug scripts for that game into `$PROTON_DEBUG_DIR/proton_$USER/`. |
 |                       | <tt>PROTON_DEBUG_DIR</tt>      | Root directory for the Proton debug scripts, `/tmp` by default. |
+|                       | <tt>PROTON_WAIT_ATTACH</tt>    | Wait for a debugger to attach to steam.exe before launching the game process. To attach to the game process at startup, debuggers should be set to follow child processes. |
 |                       | <tt>PROTON_CRASH_REPORT_DIR</tt> | Write crash logs into this directory. Does not clean up old logs, so may eat all your disk space eventually. |
 | <tt>wined3d</tt>      | <tt>PROTON_USE_WINED3D</tt>    | Use OpenGL-based wined3d instead of Vulkan-based DXVK for d3d11, d3d10, and d3d9. |
 | <tt>nod3d11</tt>      | <tt>PROTON_NO_D3D11</tt>       | Disable <tt>d3d11.dll</tt>, for d3d11 games which can fall back to and run better with d3d9. |
diff --git a/steam_helper/steam.cpp b/steam_helper/steam.cpp
index f226e672..0c1d95fd 100644
--- a/steam_helper/steam.cpp
+++ b/steam_helper/steam.cpp
@@ -62,6 +62,12 @@ EXTERN_C HANDLE CDECL __wine_make_process_system(void);
 
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(*a))
 
+static bool env_nonzero(const char *env)
+{
+    const char *v = getenv(env);
+    return v != NULL && *v && v[0] != '0';
+}
+
 static void set_active_process_pid(void)
 {
     DWORD pid = GetCurrentProcessId();
@@ -1177,6 +1183,22 @@ int main(int argc, char *argv[])
         setup_steam_registry();
         setup_steam_files();
 
+        if (env_nonzero("PROTON_WAIT_ATTACH"))
+        {
+            unsigned int sleep_count = 0;
+            WINE_TRACE("PROTON_WAIT_ATTACH is set, waiting for debugger...\n");
+            while (!IsDebuggerPresent())
+            {
+                Sleep(100);
+                ++sleep_count;
+                if (sleep_count >= 10)
+                {
+                    WINE_TRACE("still waiting for debugger...\n");
+                    sleep_count = 0;
+                }
+            }
+        }
+
         wait_handle = __wine_make_process_system();
         game_process = TRUE;
     }