diff --git a/llvm/test/tools/llvm-rc/windres-preproc.test b/llvm/test/tools/llvm-rc/windres-preproc.test
--- a/llvm/test/tools/llvm-rc/windres-preproc.test
+++ b/llvm/test/tools/llvm-rc/windres-preproc.test
@@ -4,6 +4,7 @@
 ; REQUIRES: shell
 
 ; RUN: llvm-windres -### --include-dir %p/incdir1 --include %p/incdir2 "-DFOO1=\\\"foo bar\\\"" -UFOO2 -D FOO3 --preprocessor-arg "-DFOO4=\\\"baz baz\\\"" -DFOO5=\"bar\" %p/Inputs/empty.rc %t.res | FileCheck %s --check-prefix=CHECK1
+; RUN: llvm-windres -### --include-dir %p/incdir1 --include %p/incdir2 "-DFOO1=\"foo bar\"" -UFOO2 -D FOO3 --preprocessor-arg "-DFOO4=\"baz baz\"" "-DFOO5=bar" %p/Inputs/empty.rc %t.res --use-temp-file | FileCheck %s --check-prefix=CHECK1
 ; CHECK1: {{^}} "clang" "--driver-mode=gcc" "-target" "{{.*}}-{{.*}}{{mingw32|windows-gnu}}" "-E" "-xc" "-DRC_INVOKED" "{{.*}}empty.rc" "-o" "{{.*}}preproc-{{.*}}.rc" "-I" "{{.*}}incdir1" "-I" "{{.*}}incdir2" "-D" "FOO1=\"foo bar\"" "-U" "FOO2" "-D" "FOO3" "-DFOO4=\"baz baz\"" "-D" "FOO5=bar"{{$}}
 ; RUN: llvm-windres -### --preprocessor "i686-w64-mingw32-gcc -E -DFOO=\\\"foo\\ bar\\\"" %p/Inputs/empty.rc %t.res | FileCheck %s --check-prefix=CHECK2
 ; CHECK2: {{^}} "i686-w64-mingw32-gcc" "-E" "-DFOO=\"foo bar\"" "{{.*}}empty.rc" "-o" "{{.*}}preproc-{{.*}}.rc"{{$}}
diff --git a/llvm/tools/llvm-rc/WindresOpts.td b/llvm/tools/llvm-rc/WindresOpts.td
--- a/llvm/tools/llvm-rc/WindresOpts.td
+++ b/llvm/tools/llvm-rc/WindresOpts.td
@@ -48,6 +48,10 @@
 
 defm language : LongShort<"l", "language", "Default language to use (0x0-0xffff)">;
 
+def use_temp_file: Flag<["--"], "use-temp-file">,
+                   HelpText<"Mimic GNU windres preprocessor option handling "
+                            "(don't unescape preprocessor options)">;
+
 defm verbose : F<"v", "verbose", "Enable verbose output">;
 defm version : F<"V", "version", "Display version">;
 
@@ -57,6 +61,3 @@
 def _HASH_HASH_HASH : Flag<["-"], "###">;
 
 def no_preprocess : Flag<["--"], "no-preprocess">;
-
-// Unimplemented options for compatibility
-def use_temp_file: Flag<["--"], "use-temp-file">;
diff --git a/llvm/tools/llvm-rc/llvm-rc.cpp b/llvm/tools/llvm-rc/llvm-rc.cpp
--- a/llvm/tools/llvm-rc/llvm-rc.cpp
+++ b/llvm/tools/llvm-rc/llvm-rc.cpp
@@ -461,7 +461,14 @@
     // done this double escaping) probably is confined to cases like these
     // quoted string defines, and those happen to work the same across unix
     // and windows.
-    std::string Unescaped = unescape(Arg->getValue());
+    //
+    // If GNU windres is executed with --use-temp-file, it doesn't use
+    // popen() to invoke the preprocessor, but uses another function which
+    // actually preserves tricky characters better. To mimic this behaviour,
+    // don't unescape arguments here.
+    std::string Value = Arg->getValue();
+    if (!InputArgs.hasArg(WINDRES_use_temp_file))
+      Value = unescape(Value);
     switch (Arg->getOption().getID()) {
     case WINDRES_include_dir:
       // Technically, these are handled the same way as e.g. defines, but
@@ -475,17 +482,19 @@
       break;
     case WINDRES_define:
       Opts.PreprocessArgs.push_back("-D");
-      Opts.PreprocessArgs.push_back(Unescaped);
+      Opts.PreprocessArgs.push_back(Value);
       break;
     case WINDRES_undef:
       Opts.PreprocessArgs.push_back("-U");
-      Opts.PreprocessArgs.push_back(Unescaped);
+      Opts.PreprocessArgs.push_back(Value);
       break;
     case WINDRES_preprocessor_arg:
-      Opts.PreprocessArgs.push_back(Unescaped);
+      Opts.PreprocessArgs.push_back(Value);
       break;
     }
   }
+  // TODO: If --use-temp-file is set, we shouldn't be unescaping
+  // the --preprocessor argument either, only splitting it.
   if (InputArgs.hasArg(WINDRES_preprocessor))
     Opts.PreprocessCmd =
         unescapeSplit(InputArgs.getLastArgValue(WINDRES_preprocessor));