diff --git a/openmp/runtime/src/CMakeLists.txt b/openmp/runtime/src/CMakeLists.txt
index 61c0bacc9f206..698e185d9c4dd 100644
--- a/openmp/runtime/src/CMakeLists.txt
+++ b/openmp/runtime/src/CMakeLists.txt
@@ -26,16 +26,22 @@ if(${LIBOMP_OMPT_SUPPORT})
 endif()
 
 # Generate message catalog files: kmp_i18n_id.inc and kmp_i18n_default.inc
+set(LIBOMP_MESSAGE_CONVERTER_EXTRA_ARGS "")
+if("${CMAKE_SYSTEM_NAME}" STREQUAL "Emscripten")
+  # Required as Python doesn't inherit CMake's environment setup and uses the host system as the target system by default
+  set(LIBOMP_MESSAGE_CONVERTER_EXTRA_ARGS ${LIBOMP_MESSAGE_CONVERTER_EXTRA_ARGS} --target-system-override=${CMAKE_SYSTEM_NAME})
+endif()
+
 add_custom_command(
   OUTPUT  kmp_i18n_id.inc
   COMMAND ${Python3_EXECUTABLE} ${LIBOMP_TOOLS_DIR}/message-converter.py
-          --enum=kmp_i18n_id.inc ${LIBOMP_SRC_DIR}/i18n/en_US.txt
+          --enum=kmp_i18n_id.inc ${LIBOMP_MESSAGE_CONVERTER_EXTRA_ARGS} ${LIBOMP_SRC_DIR}/i18n/en_US.txt
   DEPENDS ${LIBOMP_SRC_DIR}/i18n/en_US.txt ${LIBOMP_TOOLS_DIR}/message-converter.py
 )
 add_custom_command(
   OUTPUT  kmp_i18n_default.inc
   COMMAND ${Python3_EXECUTABLE} ${LIBOMP_TOOLS_DIR}/message-converter.py
-          --default=kmp_i18n_default.inc ${LIBOMP_SRC_DIR}/i18n/en_US.txt
+          --default=kmp_i18n_default.inc ${LIBOMP_MESSAGE_CONVERTER_EXTRA_ARGS} ${LIBOMP_SRC_DIR}/i18n/en_US.txt
   DEPENDS ${LIBOMP_SRC_DIR}/i18n/en_US.txt ${LIBOMP_TOOLS_DIR}/message-converter.py
 )
 
diff --git a/openmp/runtime/tools/message-converter.py b/openmp/runtime/tools/message-converter.py
index b3e0b343c65a2..a493d64c1692d 100644
--- a/openmp/runtime/tools/message-converter.py
+++ b/openmp/runtime/tools/message-converter.py
@@ -19,6 +19,32 @@
 from libomputils import ScriptError, error
 
 
+class TargetPlatform:
+    """Convenience class for handling the target platform for configuration/compilation"""
+
+    system_override = None
+    """
+    Target system name override by the user.
+    It follows the conventions from https://docs.python.org/3/library/platform.html#platform.system
+    """
+
+    def set_system_override(override_system):
+        """
+        Set a system override for the target.
+        Please follow the style from https://docs.python.org/3/library/platform.html#platform.system
+        """
+        TargetPlatform.system_override = override_system
+
+    def system():
+        """
+        Target System name.
+        It follows the conventions from https://docs.python.org/3/library/platform.html#platform.system
+        """
+        if TargetPlatform.system_override is None:
+            return platform.system()
+        return TargetPlatform.system_override
+
+
 class ParseMessageDataError(ScriptError):
     """Convenience class for parsing message data file errors"""
 
@@ -55,7 +81,7 @@ def __init__(self, lineNumber, name, text):
         self.text = text
 
     def toSrc(self):
-        if platform.system() == "Windows":
+        if TargetPlatform.system().casefold() == "Windows".casefold():
             return re.sub(r"%([0-9])\$(s|l?[du])", r"%\1!\2!", self.text)
         return str(self.text)
 
@@ -363,6 +389,13 @@ def main():
     parser.add_argument(
         "--message", metavar="FILE", help="Generate message file named FILE"
     )
+    parser.add_argument(
+        "--target-system-override",
+        metavar="TARGET_SYSTEM_NAME",
+        help="Target System override.\n"
+        "By default the target system is the host system\n"
+        "See possible values at https://docs.python.org/3/library/platform.html#platform.system",
+    )
     parser.add_argument("inputfile")
     commandArgs = parser.parse_args()
 
@@ -371,6 +404,8 @@ def main():
         return
     data = MessageData.create(commandArgs.inputfile)
     prefix = commandArgs.prefix
+    if commandArgs.target_system_override:
+        TargetPlatform.set_system_override(commandArgs.target_system_override)
     if commandArgs.enum:
         generate_enum_file(commandArgs.enum, prefix, data)
     if commandArgs.default:
@@ -378,7 +413,7 @@ def main():
     if commandArgs.signature:
         generate_signature_file(commandArgs.signature, data)
     if commandArgs.message:
-        if platform.system() == "Windows":
+        if TargetPlatform.system().casefold() == "Windows".casefold():
             generate_message_file_windows(commandArgs.message, data)
         else:
             generate_message_file_unix(commandArgs.message, data)