diff --git a/tools/cmake/common/ExportSp.cmake b/tools/cmake/common/ExportSp.cmake
index faa69fe..1e550ad 100644
--- a/tools/cmake/common/ExportSp.cmake
+++ b/tools/cmake/common/ExportSp.cmake
@@ -1,5 +1,5 @@
 #-------------------------------------------------------------------------------
-# Copyright (c) 2020-2022, Arm Limited and Contributors. All rights reserved.
+# Copyright (c) 2020-2023, Arm Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -92,11 +92,18 @@
 	if (DEFINED EXPORT_JSON_IN)
 		configure_file(${EXPORT_JSON_IN} ${CMAKE_CURRENT_BINARY_DIR}/${EXPORT_SP_NAME}.json @ONLY NEWLINE_STYLE UNIX)
 		install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${EXPORT_SP_NAME}.json DESTINATION ${TS_ENV}/json)
-
 		find_package(Python3 REQUIRED COMPONENTS Interpreter)
-		execute_process(COMMAND ${Python3_EXECUTABLE} ${TS_ROOT}/tools/python/merge_json.py
-				${CMAKE_INSTALL_PREFIX}/${TS_ENV}/json/sp_layout.json
-				${CMAKE_CURRENT_BINARY_DIR}/${EXPORT_SP_NAME}.json
+		# Create a cmake code fragment to merge the SP json files describing the SPs to be loaded by
+		# BL2. This is only needed when FIP packaging is used.
+		# The code fragment ensures merging is done installation time.
+		string(JOIN "\n" install_script
+			"execute_process(COMMAND ${Python3_EXECUTABLE}"
+			"	${TS_ROOT}/tools/python/merge_json.py"
+			"		-vvv"
+			"		-o \${CMAKE_INSTALL_PREFIX}/@TS_ENV@/json/sp_layout.json"
+			"		\${CMAKE_INSTALL_PREFIX}/@TS_ENV@/json/*.json)"
 		)
+		string(CONFIGURE "${install_script}" install_script @ONLY)
+		install(SCRIPT CODE "${install_script}")
 	endif()
 endfunction()
diff --git a/tools/python/merge_json.py b/tools/python/merge_json.py
index 68ad10b..79898c8 100644
--- a/tools/python/merge_json.py
+++ b/tools/python/merge_json.py
@@ -1,27 +1,125 @@
 #!/usr/bin/env python3
 # SPDX-License-Identifier: BSD-3-Clause
 #
-# Copyright (c) 2022, Arm Limited. All rights reserved.
+# Copyright (c) 2022-2023, Arm Limited. All rights reserved.
 
-"""
-Merge two json files, the second is merged into the first. If the first file
-doesn't exists yet, it will be created, along with its parent directories.
+"""Merge json files and print the result to STDOUT.
+
+Source files are specified with a list of file names. Any name in the list can
+be a glob pattern. Glob patterns act if the returned list of file names were
+passed instead. The list returned by glob is not sorted. All files are
+processed in the order being found in the argument list.
+
+Note: do not forget to quote globing patterns when running the tool from a
+      shell.
 """
 
+import argparse
+import errno
+import glob
 import json
+import logging
 import os.path
 import sys
 
-if os.path.isfile(sys.argv[1]):
-    with open(sys.argv[1], "rt", encoding="ascii") as f:
-        combined = json.load(f)
-else:
-    os.makedirs(os.path.dirname(sys.argv[1]), exist_ok=True)
-    combined = {}
+# initialize logger
+logging.getLogger('merge_json')
+logging.basicConfig(level=logging.ERROR)
 
-with open(sys.argv[2], "rt", encoding="ascii") as f:
-    current = json.load(f)
-    combined = {**combined, **current}
 
-with open(sys.argv[1], "wt", encoding="ascii") as f:
-    json.dump(combined, f, indent=4)
+def parse_arguments(args):
+    parser = argparse.ArgumentParser(
+                prog=os.path.basename(args[0]),
+                description=__doc__,
+                formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument(
+                "-e", "--exclude",
+                default=None,
+                metavar="<exclude pattern>",
+                help="Exclude files matching this pattern.")
+    parser.add_argument(
+                "-o", "--output_file",
+                default=None,
+                metavar="<path to output file>",
+                help="Write result to this file instead of STDOUT")
+    parser.add_argument(
+                "-v",
+                action='append_const', const='v',
+                metavar="<verbosity level>",
+                help="Set the amount of information printed to STDERR." +
+                     " Passing more times gives more info.")
+    parser.add_argument(
+                "-i", "--ignore-missing",
+                dest="ignore_missing",
+                action='store_const', const=True, default=False,
+                help="Ignore missing source files or source globs returning" +
+                     " empty result.")
+    parser.add_argument(
+                'source_list',
+                nargs="+",
+                metavar="<source file>",
+                help="List of source files (file name can be glob pattern).")
+    parsed_args = parser.parse_args(args[1:])
+    # Count -v arguments to logging level
+    if parsed_args.v:
+        llv = len(parsed_args.v)
+        if llv > 3:
+            llv = 3
+    else:
+        llv = 0
+    parsed_args.log_level = [logging.ERROR, logging.WARNING, logging.INFO,
+                             logging.DEBUG][llv]
+    return (parsed_args)
+
+
+def merge_files(parsed_args):
+    logger = logging.getLogger('merge_json')
+
+    logger.info(
+        "Merging " + str(parsed_args.source_list) + " to " +
+        (parsed_args.output_file if parsed_args.output_file else "STDOUT"))
+
+    result = {}
+    exclude_list = None
+
+    if parsed_args.exclude:
+        exclude_list = glob.glob(parsed_args.exclude, recursive=True)
+        if exclude_list:
+            logger.debug("Excluding files: %s" % exclude_list)
+        else:
+            logger.warning("Exclude pattern matches no files.")
+
+    for pattern in parsed_args.source_list:
+        file_list = glob.glob(pattern, recursive=True)
+        logger.debug("Globing " + pattern + " = " + str(file_list))
+        if not file_list:
+            logger.error("Pattern \"%s\" does not match any file" % pattern)
+            if not parsed_args.ignore_missing:
+                raise (FileNotFoundError(
+                        errno.ENOENT,
+                        "Pattern does not match any file",
+                        pattern))
+
+        for file in list(file_list):
+            if exclude_list and file in list(exclude_list):
+                logger.debug("excluding file " + file)
+                continue
+            logger.debug("Reding source file " + file)
+            with open(file, "rt", encoding="utf8", errors="strict") as f:
+                result.update(json.load(f))
+
+    if parsed_args.output_file is not None:
+        path = os.path.dirname(parsed_args.output_file)
+        if path:
+            os.makedirs(path, exist_ok=True)
+        with open(parsed_args.output_file, "w", encoding="utf8") as f:
+            json.dump(result, f, indent=4)
+    else:
+        print(json.dumps(result, indent=4))
+
+
+if __name__ == "__main__":
+    parsed_args = parse_arguments(sys.argv)
+    logger = logging.getLogger('merge_json')
+    logger.setLevel(parsed_args.log_level)
+    merge_files(parsed_args)