diff --git a/doc/man/wesnoth.6 b/doc/man/wesnoth.6
index 9e1045cb660..eef7bbbff61 100644
--- a/doc/man/wesnoth.6
+++ b/doc/man/wesnoth.6
@@ -249,9 +249,14 @@ Example:
 For details regarding the preprocessor visit:
 https://wiki.wesnoth.org/PreprocessorRef#Command-line_preprocessor.
 .TP
+.BI --preprocess-string \ source-string
+preprocesses a given string and writes the output to stdout.
+.TP
 .BI --preprocess-defines= DEFINE1 , DEFINE2 , ...
 comma separated list of defines to be used by the
 .B --preprocess
+or
+.B --preprocess-string
 command. If
 .B SKIP_CORE
 is in the define list the "data/core" directory won't be preprocessed.
@@ -259,6 +264,8 @@ is in the define list the "data/core" directory won't be preprocessed.
 .BI --preprocess-input-macros \ source-file
 used only by the
 .B --preprocess
+or
+.B --preprocess-string
 command. Specifies a file that contains
 .BR [preproc_define] s
 to be included before preprocessing.
@@ -266,7 +273,9 @@ to be included before preprocessing.
 .BI --preprocess-output-macros[ =target-file ]
 used only by the
 .B --preprocess
-command. Will output all preprocessed macros in the target file. If the file is not specified
+command (But not by the
+.B --preprocess-string
+command). Will output all preprocessed macros in the target file. If the file is not specified
 the output will be file '_MACROS_.cfg' in the target directory of preprocess's command. The
 output file can be passed to
 .BR --preprocess-input-macros .
diff --git a/src/commandline_options.cpp b/src/commandline_options.cpp
index fd3eac1f87a..7f6db4dddf1 100644
--- a/src/commandline_options.cpp
+++ b/src/commandline_options.cpp
@@ -29,6 +29,7 @@
 #include <boost/program_options/variables_map.hpp>  // for variables_map, etc
 
 #include <array>
+#include <string>
 
 namespace po = boost::program_options;
 
@@ -291,6 +292,7 @@ commandline_options::commandline_options(const std::vector<std::string>& args)
 		("output,o", po::value<std::string>(), "output to specified file")
 		("patch,P", po::value<two_strings>()->multitoken(), "apply a patch to a preprocessed WML document." IMPLY_TERMINAL)
 		("preprocess,p", po::value<two_strings>()->multitoken(), "requires two arguments: <file/folder> <target directory>. Preprocesses a specified file/folder. The preprocessed file(s) will be written in the specified target directory: a plain cfg file and a processed cfg file." IMPLY_TERMINAL)
+		("preprocess-string", po::value<std::string>(), "preprocess given string" IMPLY_TERMINAL)
 		("preprocess-defines", po::value<std::string>(), "comma separated list of defines to be used by '--preprocess' command. If 'SKIP_CORE' is in the define list the data/core won't be preprocessed. Example: --preprocess-defines=FOO,BAR")
 		("preprocess-input-macros", po::value<std::string>(), "used only by the '--preprocess' command. Specifies source file <arg> that contains [preproc_define]s to be included before preprocessing.")
 		("preprocess-output-macros", po::value<std::string>()->implicit_value(std::string()), "used only by the '--preprocess' command. Will output all preprocessed macros in the target file <arg>. If the file is not specified the output will be file '_MACROS_.cfg' in the target directory of preprocess's command.")
@@ -413,6 +415,10 @@ commandline_options::commandline_options(const std::vector<std::string>& args)
 		preprocess_path = vm["preprocess"].as<two_strings>().first;
 		preprocess_target = vm["preprocess"].as<two_strings>().second;
 	}
+	if(vm.count("preprocess-string"))
+	{
+		preprocess_source_string = vm["preprocess-string"].as<std::string>();
+	}
 	if(vm.count("diff"))
 	{
 		do_diff = true;
diff --git a/src/commandline_options.hpp b/src/commandline_options.hpp
index f8f6d248e79..41e75768d37 100644
--- a/src/commandline_options.hpp
+++ b/src/commandline_options.hpp
@@ -164,6 +164,8 @@ public:
 	utils::optional<std::string> preprocess_path;
 	/** Target (output) path that was given to the --preprocess option. */
 	utils::optional<std::string> preprocess_target;
+	/** String to preprocess */
+	utils::optional<std::string> preprocess_source_string;
 	/** Pair of AxB values specified after --resolution. Changes Wesnoth resolution. */
 	utils::optional<std::pair<int,int>> resolution;
 	/** RNG seed specified by --rng-seed option. Initializes RNG with given seed. */
@@ -178,7 +180,7 @@ public:
 	utils::optional<std::string> render_image;
 	/** Output file to put rendered image path in. Optional second parameter after --render-image */
 	utils::optional<std::string> render_image_dst;
-  /** Path of which to generate a spritesheet */
+	/** Path of which to generate a spritesheet */
 	utils::optional<std::string> generate_spritesheet;
 	/** True if --screenshot was given on the command line. Starts Wesnoth in screenshot mode. */
 	bool screenshot;
diff --git a/src/editor/map/map_context.cpp b/src/editor/map/map_context.cpp
index 26fa1096b10..6d620d9c517 100644
--- a/src/editor/map/map_context.cpp
+++ b/src/editor/map/map_context.cpp
@@ -759,7 +759,7 @@ config map_context::to_config()
 		config& mods = u.add_child("modifications");
 		if(unit.loyal()) {
 			config trait_loyal;
-			read(trait_loyal, preprocess_string("{TRAIT_LOYAL}", &traits_map, "wesnoth-editor"));
+			read(trait_loyal, preprocess_string("{TRAIT_LOYAL}", &traits_map, "wesnoth-help"));
 			mods.append(trait_loyal);
 		}
 		//TODO this entire block could also be replaced by unit.write(u, true)
diff --git a/src/wesnoth.cpp b/src/wesnoth.cpp
index 1d2f10047bb..776e7f2263e 100644
--- a/src/wesnoth.cpp
+++ b/src/wesnoth.cpp
@@ -123,6 +123,64 @@ static void safe_exit(int res)
 	exit(res);
 }
 
+static void handle_preprocess_string(const commandline_options& cmdline_opts)
+{
+	preproc_map defines_map;
+
+	if(cmdline_opts.preprocess_input_macros) {
+		std::string file = *cmdline_opts.preprocess_input_macros;
+		if(!filesystem::file_exists(file)) {
+			PLAIN_LOG << "please specify an existing file. File " << file << " doesn't exist.";
+			return;
+		}
+
+		PLAIN_LOG << "Reading cached defines from: " << file;
+
+		config cfg;
+
+		try {
+			filesystem::scoped_istream stream = filesystem::istream_file(file);
+			read(cfg, *stream);
+		} catch(const config::error& e) {
+			PLAIN_LOG << "Caught a config error while parsing file '" << file << "':\n" << e.message;
+		}
+
+		int read = 0;
+
+		// use static preproc_define::read_pair(config) to make a object
+		for(const auto [_, cfg] : cfg.all_children_view()) {
+			const preproc_map::value_type def = preproc_define::read_pair(cfg);
+			defines_map[def.first] = def.second;
+			++read;
+		}
+
+		PLAIN_LOG << "Read " << read << " defines.";
+	}
+
+	if(cmdline_opts.preprocess_defines) {
+		// add the specified defines
+		for(const std::string& define : *cmdline_opts.preprocess_defines) {
+			if(define.empty()) {
+				PLAIN_LOG << "empty define supplied";
+				continue;
+			}
+
+			LOG_PREPROC << "adding define: " << define;
+			defines_map.emplace(define, preproc_define(define));
+		}
+	}
+
+	// add the WESNOTH_VERSION define
+	defines_map["WESNOTH_VERSION"] = preproc_define(game_config::wesnoth_version.str());
+
+	// preprocess resource
+	PLAIN_LOG << "preprocessing specified string: " << *cmdline_opts.preprocess_source_string;
+	const utils::ms_optimer timer(
+		[](const auto& timer) { PLAIN_LOG << "preprocessing finished. Took " << timer << " ticks."; });
+	std::cout << preprocess_string(*cmdline_opts.preprocess_source_string, &defines_map) << std::endl;
+	PLAIN_LOG << "added " << defines_map.size() << " defines.";
+}
+
 static void handle_preprocess_command(const commandline_options& cmdline_opts)
 {
 	preproc_map input_macros;
@@ -497,6 +555,11 @@ static int process_command_args(commandline_options& cmdline_opts)
 		return 0;
 	}
 
+	if(cmdline_opts.preprocess_source_string.has_value()) {
+		handle_preprocess_string(cmdline_opts);
+		return 0;
+	}
+
 	if(cmdline_opts.validate_wml) {
 		std::string schema_path;
 		if(cmdline_opts.validate_with) {