Index: lldb/include/lldb/Utility/Diagnostics.h
===================================================================
--- lldb/include/lldb/Utility/Diagnostics.h
+++ lldb/include/lldb/Utility/Diagnostics.h
@@ -43,6 +43,7 @@
   static Diagnostics &Instance();
   static void Initialize();
   static void Terminate();
+  static bool Enabled();
 
   /// Create a unique diagnostic directory.
   static llvm::Expected<FileSpec> CreateUniqueDirectory();
Index: lldb/source/Core/Debugger.cpp
===================================================================
--- lldb/source/Core/Debugger.cpp
+++ lldb/source/Core/Debugger.cpp
@@ -810,6 +810,22 @@
   if (!GetOutputFile().GetIsTerminalWithColors())
     SetUseColor(false);
 
+  if (Diagnostics::Enabled()) {
+    Diagnostics::Instance().AddCallback(
+        [&](const FileSpec &dir) -> llvm::Error {
+          for (auto &entry : m_stream_handlers) {
+            llvm::StringRef log_path = entry.first();
+            llvm::StringRef file_name = llvm::sys::path::filename(log_path);
+            FileSpec destination = dir.CopyByAppendingPathComponent(file_name);
+            std::error_code ec =
+                llvm::sys::fs::copy_file(entry.first(), destination.GetPath());
+            if (ec)
+              return llvm::errorCodeToError(ec);
+          }
+          return llvm::Error::success();
+        });
+  }
+
 #if defined(_WIN32) && defined(ENABLE_VIRTUAL_TERMINAL_PROCESSING)
   // Enabling use of ANSI color codes because LLDB is using them to highlight
   // text.
Index: lldb/source/Utility/Diagnostics.cpp
===================================================================
--- lldb/source/Utility/Diagnostics.cpp
+++ lldb/source/Utility/Diagnostics.cpp
@@ -30,6 +30,8 @@
   InstanceImpl().reset();
 }
 
+bool Diagnostics::Enabled() { return InstanceImpl().operator bool(); }
+
 Optional<Diagnostics> &Diagnostics::InstanceImpl() {
   static Optional<Diagnostics> g_diagnostics;
   return g_diagnostics;
Index: lldb/test/Shell/Diagnostics/TestCopyLogs.test
===================================================================
--- /dev/null
+++ lldb/test/Shell/Diagnostics/TestCopyLogs.test
@@ -0,0 +1,7 @@
+# RUN: rm -rf %t
+# RUN: mkdir -p %t
+# The "ll''db" below is not a typo but a way to prevent lit from substituting 'lldb'.
+# RUN: %lldb -o 'log enable ll''db commands -f %t/commands.log' -o 'diagnostics dump -d %t/diags'
+# RUN: cat %t/diags/commands.log | FileCheck %s
+
+# CHECK: Processing command: diagnostics dump