diff --git a/.gitignore b/.gitignore
index 8d1ca1d523e79..c2bc162482f59 100644
--- a/.gitignore
+++ b/.gitignore
@@ -50,3 +50,6 @@ ipch/
 *.*codeanalysis*
 read.lock
 fileList.bin
+
+*.js
+*.wasm
diff --git a/ACE/ACE-INSTALL.html b/ACE/ACE-INSTALL.html
index 185fe6d9d5235..e87072b692e23 100644
--- a/ACE/ACE-INSTALL.html
+++ b/ACE/ACE-INSTALL.html
@@ -284,6 +284,7 @@ <h1><a name="aceinstall">Building and Installing ACE</a></h1>
 <li><a href="#win32">Windows (including MinGW and Cygwin)</a></li>
 <li><a href="#vxworks">VxWorks</a></li>
 <li><a href="#android">Android</a></li>
+<li><a href="#emscripten">Emscripten WebAssembly</a></li>
 </ul>
 
 <h2>General Rules</h2>
@@ -1823,7 +1824,7 @@ <h3><a name="android-openssl">OpenSSL</a></h3>
   OpenSSL. On Android, OpenSSL isn't part of the NDK Library and Android
   preloads the system SSL library (either OpenSSL or BoringSSL) for the Java
   Android API. This means OpenSSL <b>MUST</b> be statically linked to avoid
-  conflicts with the almost certianly incompatible system SSL library.
+  conflicts with the almost certainly incompatible system SSL library.
 
   To build OpenSSL for Android, please read <code>NOTES.ANDROID</code> that comes
   with OpenSSL's source code. The static libraries will used if the shared
@@ -1833,6 +1834,43 @@ <h3><a name="android-openssl">OpenSSL</a></h3>
   building OpenSSL.
 </p>
 
+<hr align="left" width="50%">
+
+<h2><a name="emscripten">Building ACE for Emscripten WebAssembly</a></h2>
+
+<p><b>NOTE: This has only been tested on Linux with NodeJS 16.18.</b></p>
+
+<a href="https://emscripten.org/">Emscripten</a>
+is a LLVM toolchain that allows compiling C++ to
+<a href="https://en.wikipedia.org/wiki/WebAssembly">WebAssembly</a>
+that can be ran on a web browser or <a href="https://nodejs.org">NodeJS</a>.
+
+<h3>Building</h3>
+
+<ol>
+  <li>Download and setup <a href="https://emscripten.org/docs/getting_started/downloads.html">emscripten</a>.</li>
+  <li>Run <code>source emsdk_env.sh</code> in <code>emsdk</code>.</li>
+  <li>Make sure MPC is available and <code>MPC_ROOT</code> is set.</li>
+  <li>Configure ACE:
+    <ol>
+      <li><code>$ACE_ROOT/bin/MakeProjectCreator/config/default.features</code>
+        should contain <code>no_cxx11=0</code></li>
+      <li><code>$ACE_ROOT/include/makeinclude/platform_macros.GNU</code> should contain
+        <code>include $(ACE_ROOT)/include/makeinclude/platform_emscripten.GNU</code></li>
+      <li><code>$ACE_ROOT/ace/config.h</code> should contain
+        <code>#include "config-emscripten.h"</code></li>
+      <li><code>cd $ACE_ROOT/ace &amp;&amp; mwc.pl -type gnuace .</code></li>
+    </ol>
+  </li>
+  <li>Build ACE: <code>cd $ACE_ROOT/ace &amp;&amp; make -j4</code></li>
+</ol>
+
+<h3>Running Tests</h3>
+
+<pre class="indent">
+DOC_TEST_1=NODEJS NODEJS_OS=local ./run_test.pl -Config STATIC -Config NODEJS
+</pre>
+
 <hr>
 <h1><a name="svcsinstall">Building and Installing ACE Network Services</a></h1>
 
diff --git a/ACE/ace/Notification_Queue.h b/ACE/ace/Notification_Queue.h
index 914904ac296fc..18749e4f2a221 100644
--- a/ACE/ace/Notification_Queue.h
+++ b/ACE/ace/Notification_Queue.h
@@ -13,6 +13,8 @@
 #include "ace/Intrusive_List.h"
 #include "ace/Intrusive_List_Node.h"
 #include "ace/Unbounded_Queue.h"
+#include "ace/Synch_Traits.h"
+#include "ace/Thread_Mutex.h"
 
 ACE_BEGIN_VERSIONED_NAMESPACE_DECL
 
diff --git a/ACE/ace/Timer_Queue_T.inl b/ACE/ace/Timer_Queue_T.inl
index 15c0e8ef99d5f..72dc9e71e7067 100644
--- a/ACE/ace/Timer_Queue_T.inl
+++ b/ACE/ace/Timer_Queue_T.inl
@@ -1,4 +1,7 @@
 // -*- C++ -*-
+
+#include "ace/Guard_T.h"
+
 ACE_BEGIN_VERSIONED_NAMESPACE_DECL
 
 template <class TYPE, class FUNCTOR> ACE_INLINE FUNCTOR &
diff --git a/ACE/ace/config-emscripten.h b/ACE/ace/config-emscripten.h
new file mode 100644
index 0000000000000..7ec287328aaae
--- /dev/null
+++ b/ACE/ace/config-emscripten.h
@@ -0,0 +1,54 @@
+#ifndef ACE_CONFIG_EMSCRIPTEN_H
+#define ACE_CONFIG_EMSCRIPTEN_H
+
+#define ACE_EMSCRIPTEN
+
+#define ACE_HAS_CPP11
+
+// Threading
+#define ACE_MT_SAFE 1
+#define ACE_HAS_THREADS 1
+#define ACE_HAS_PTHREADS
+#define ACE_HAS_PTHREADS_UNIX98_EXT
+#define ACE_HAS_THREAD_SPECIFIC_STORAGE
+
+// Basic Types
+#define ACE_HAS_SSIZE_T
+#define ACE_HAS_WCHAR
+
+// Time
+#define ACE_HAS_POSIX_TIME
+#define ACE_LACKS_TIMESPEC_T
+#define ACE_HAS_NONCONST_SELECT_TIMEVAL
+#define ACE_HAS_VOIDPTR_GETTIMEOFDAY
+
+// Everything else
+#define ACE_HAS_UCONTEXT_T
+#define ACE_HAS_MSG
+#define ACE_HAS_CPU_SET_T
+#define ACE_LACKS_ISCTYPE
+#define ACE_HAS_STRBUF_T
+#define ACE_HAS_SOCKLEN_T
+#define ACE_LACKS_AUTO_PTR
+#define ACE_HAS_SIGINFO_T
+#define ACE_LACKS_SIGINFO_H
+#define ACE_HAS_CONSISTENT_SIGNAL_PROTOTYPES
+#define ACE_HAS_3_PARAM_WCSTOK
+#define ACE_LACKS_ITOW
+#define ACE_LACKS_WCSICMP
+#define ACE_LACKS_WCSNICMP
+#define ACE_HAS_DIRENT
+#define ACE_HAS_4_4BSD_SENDMSG_RECVMSG
+
+// These exist, but don't seem to work correctly
+#define ACE_LACKS_PWD_FUNCTIONS
+
+#include "config-posix.h"
+#include "config-g++-common.h"
+
+// Not supported: https://github.com/emscripten-core/emscripten/issues/18050
+#ifdef ACE_HAS_AIO_CALLS
+#  undef ACE_HAS_AIO_CALLS
+#endif
+
+#endif
diff --git a/ACE/ace/os_include/sys/os_types.h b/ACE/ace/os_include/sys/os_types.h
index b179c7051ad73..9d5fe106549a2 100644
--- a/ACE/ace/os_include/sys/os_types.h
+++ b/ACE/ace/os_include/sys/os_types.h
@@ -53,7 +53,8 @@ typedef double ACE_timer_t;
 
 #if defined (ACE_SIZEOF_LONG) && ACE_SIZEOF_LONG == 8
    typedef off_t ACE_LOFF_T;
-#elif defined (__FreeBSD__) || defined (__NetBSD__) || defined (__OpenBSD__) || defined (__APPLE__)
+#elif defined (__FreeBSD__) || defined (__NetBSD__) || defined (__OpenBSD__) || defined (__APPLE__) || \
+  defined (ACE_EMSCRIPTEN)
    typedef off_t ACE_LOFF_T;
 #elif defined (__QNX__)
    typedef off64_t ACE_LOFF_T;
diff --git a/ACE/bin/PerlACE/ProcessNodeJS.pm b/ACE/bin/PerlACE/ProcessNodeJS.pm
new file mode 100644
index 0000000000000..92be88dfe1188
--- /dev/null
+++ b/ACE/bin/PerlACE/ProcessNodeJS.pm
@@ -0,0 +1,21 @@
+package PerlACE::ProcessNodeJS;
+
+use strict;
+
+use PerlACE::Process;
+our @ISA = qw(PerlACE::Process);
+
+sub new {
+  my $class = shift();
+  my $name = shift();
+  my $args = shift();
+  my $node_args = shift() // '';
+
+  my $self = $class->SUPER::new("$name.js", $node_args);
+  bless($self, $class);
+  $self->IgnoreExeSubDir(1);
+  $self->{VALGRIND_CMD} = "node $node_args";
+  return $self;
+}
+
+1;
diff --git a/ACE/bin/PerlACE/Run_Test.pm b/ACE/bin/PerlACE/Run_Test.pm
index fe0bfb74aff49..ed9ddea0b2418 100644
--- a/ACE/bin/PerlACE/Run_Test.pm
+++ b/ACE/bin/PerlACE/Run_Test.pm
@@ -48,6 +48,11 @@ if ($PerlACE::Android_Test) {
     require PerlACE::ProcessAndroid;
 }
 
+$PerlACE::NodeJS_Test = $config->check_config("NODEJS");
+if ($PerlACE::NodeJS_Test) {
+    require PerlACE::ProcessNodeJS;
+}
+
 # Figure out the svc.conf extension
 $svcconf_ext = $ENV{'ACE_RUNTEST_SVCCONF_EXT'};
 if (!defined $svcconf_ext) {
diff --git a/ACE/bin/PerlACE/TestTarget.pm b/ACE/bin/PerlACE/TestTarget.pm
index 83d1d8f91c470..7e2b2b5be4226 100644
--- a/ACE/bin/PerlACE/TestTarget.pm
+++ b/ACE/bin/PerlACE/TestTarget.pm
@@ -82,9 +82,10 @@ sub new
 {
     my $proto = shift;
     my $class = ref ($proto) || $proto;
-    my $self = {};
-
     my $config_name = shift;
+
+    my $self = {config_name => $config_name};
+
     bless ($self, $class);
     $self->GetConfigSettings($config_name);
 
@@ -505,7 +506,7 @@ sub DeleteFile ($)
            print STDERR "Deleting remote $file from path $newfile using $cmd\n";
         }
         if (system ($cmd) != 0) {
-        	print STDERR "ERROR executing [".$cmd."]\n";
+          print STDERR "ERROR executing [".$cmd."]\n";
         }
     } else {
         unlink ($newfile);
@@ -523,9 +524,9 @@ sub GetFile ($)
         $remote_file = $self->LocalFile($local_file);
     }
     if (defined $self->{GET_CMD}) {
-	    if (system ($self->{GET_CMD}.' '.$remote_file.' '.$local_file) != 0) {
-	    	print STDERR "ERROR executing [".$self->{GET_CMD}." $remote_file $local_file]\n";
-	    }
+      if (system ($self->{GET_CMD}.' '.$remote_file.' '.$local_file) != 0) {
+        print STDERR "ERROR executing [".$self->{GET_CMD}." $remote_file $local_file]\n";
+      }
     }
     elsif (($remote_file ne $local_file) &&
         (File::Spec->rel2abs($remote_file) ne File::Spec->rel2abs($local_file))) {
@@ -541,9 +542,9 @@ sub PutFile ($)
     my $src = shift;
     my $dest = $self->LocalFile ($src);
     if (defined $self->{PUT_CMD}) {
-	    if (system ($self->{PUT_CMD}.' '.$src.' '.$dest) != 0) {
-	    	print STDERR "ERROR executing [".$self->{PUT_CMD}." $src $dest]\n";
-	    }
+      if (system ($self->{PUT_CMD}.' '.$src.' '.$dest) != 0) {
+        print STDERR "ERROR executing [".$self->{PUT_CMD}." $src $dest]\n";
+      }
     }
     elsif (($src ne $dest) &&
         (File::Spec->rel2abs($src) ne File::Spec->rel2abs($dest))) {
@@ -594,7 +595,14 @@ sub WaitForFileTimed ($)
 sub CreateProcess ($)
 {
     my $self = shift;
-    my $process = new PerlACE::Process (@_);
+
+    my $process;
+    if ($self->{config_name} eq 'NODEJS') {
+        $process = new PerlACE::ProcessNodeJS(@_);
+    } else {
+        $process = new PerlACE::Process (@_);
+    }
+
     $process->Target($self);
     return $process;
 }
diff --git a/ACE/include/makeinclude/platform_clang_common.GNU b/ACE/include/makeinclude/platform_clang_common.GNU
index 667d394e1da0e..61992f911b3f5 100644
--- a/ACE/include/makeinclude/platform_clang_common.GNU
+++ b/ACE/include/makeinclude/platform_clang_common.GNU
@@ -9,9 +9,11 @@ ifneq ($(CROSS_COMPILE),)
     CXX = ${CROSS_COMPILE}clang++${CROSS_COMPILE_SUFFIX}
     AR  = ${CROSS_COMPILE}ar${CROSS_COMPILE_SUFFIX}
   endif
-  # Cross-linker requires this for linked in shared libs that depend
-  # themselves on other shared libs (not directly linked in)
-  LDFLAGS += -Wl,-rpath-link,$(ACE_ROOT)/lib
+  ifneq ($(static_libs_only), 1)
+    # Cross-linker requires this for linked in shared libs that depend
+    # themselves on other shared libs (not directly linked in)
+    LDFLAGS += -Wl,-rpath-link,$(ACE_ROOT)/lib
+  endif
   ifneq (,$(HOST_ROOT))
     TAO_IDLFLAGS += -g $(HOST_ROOT)/bin/ace_gperf
     TAO_IDL = $(HOST_ROOT)/bin/tao_idl
diff --git a/ACE/include/makeinclude/platform_emscripten.GNU b/ACE/include/makeinclude/platform_emscripten.GNU
new file mode 100644
index 0000000000000..d00b9c4ce5595
--- /dev/null
+++ b/ACE/include/makeinclude/platform_emscripten.GNU
@@ -0,0 +1,31 @@
+ACE_PLATFORM_CONFIG ?= config-emscripten.h
+EXEEXT = .js
+
+debug ?= 1
+optimize ?= 0
+threads ?= 1
+inline ?= 1
+static_libs_only = 1
+
+CROSS_COMPILE := THIS_VALUE_SHOULD_NOT_BE_USED
+override_cross_compile = 1
+CC = emcc
+CXX = em++
+AR = emar
+LD = emcc
+
+ifeq ($(threads),1)
+  FLAGS_C_CC += -pthread
+  LDFLAGS += -pthread
+  LIBS += -lrt
+endif
+
+ifeq ($(debug),1)
+  LDFLAGS += -sASSERTIONS=2
+endif
+
+# TODO: Require choosing Filesystem model:
+# https://emscripten.org/docs/api_reference/Filesystem-API.html
+LDFLAGS += -sNODERAWFS=1
+
+include $(ACE_ROOT)/include/makeinclude/platform_clang_common.GNU
diff --git a/ACE/tests/OS_Test.cpp b/ACE/tests/OS_Test.cpp
index b9fad77374903..b40832466fc93 100644
--- a/ACE/tests/OS_Test.cpp
+++ b/ACE/tests/OS_Test.cpp
@@ -1208,7 +1208,7 @@ ace_ctype_test ()
       ++retval;
     }
 
-  return 0;
+  return retval;
 }
 
 int