diff --git a/lld/CMakeLists.txt b/lld/CMakeLists.txt
--- a/lld/CMakeLists.txt
+++ b/lld/CMakeLists.txt
@@ -193,6 +193,15 @@
 option(LLD_BUILD_TOOLS
   "Build the lld tools. If OFF, just generate build targets." ON)
 
+set(LLD_DEFAULT_LD_LLD_BACKEND "ELF"
+    CACHE STRING "Default backend for ld.lld, can be either ELF (default) or MINGW")
+string(TOUPPER "${LLD_DEFAULT_LD_LLD_BACKEND}" uppercase_LLD_DEFAULT_LD_LLD_BACKEND)
+if (uppercase_LLD_DEFAULT_LD_LLD_BACKEND MATCHES "^ELF$|^MINGW$")
+  add_definitions("-DLLD_DEFAULT_LD_LLD_BACKEND=\"${uppercase_LLD_DEFAULT_LD_LLD_BACKEND}\"")
+else()
+  message(FATAL_ERROR "LLD_DEFAULT_LD_LLD_BACKEND can only be either ELF or MINGW")
+endif()
+
 if (MSVC)
   add_definitions(-wd4530) # Suppress 'warning C4530: C++ exception handler used, but unwind semantics are not enabled.'
   add_definitions(-wd4062) # Suppress 'warning C4062: enumerator X in switch of enum Y is not handled' from system header.
diff --git a/lld/tools/lld/lld.cpp b/lld/tools/lld/lld.cpp
--- a/lld/tools/lld/lld.cpp
+++ b/lld/tools/lld/lld.cpp
@@ -92,7 +92,8 @@
       continue;
     return isPETargetName(*(it + 1));
   }
-  return false;
+
+  return LLD_DEFAULT_LD_LLD_BACKEND == "MINGW" ? true : false;
 }
 
 static Flavor parseProgname(StringRef progname) {