diff --git a/js/src/js-config.in b/js/src/js-config.in
index 9cd41d613d..302d2501a8 100644
--- a/js/src/js-config.in
+++ b/js/src/js-config.in
@@ -108,7 +108,7 @@ if test "$echo_libdir" = "yes"; then
 fi
 
 if test "$echo_cflags" = "yes"; then
-    echo "-std=gnu++11 -include $includedir/$JS_LIBRARY_NAME/js/RequiredDefines.h -I$includedir/$JS_LIBRARY_NAME $NSPR_CFLAGS"
+    echo "-std=gnu++17 -include $includedir/$JS_LIBRARY_NAME/js/RequiredDefines.h -I$includedir/$JS_LIBRARY_NAME $NSPR_CFLAGS"
 fi
 
 if test "$echo_libs" = "yes"; then
diff --git a/media/ffvpx/libavutil/random_seed.c b/media/ffvpx/libavutil/random_seed.c
index 21d187c5a4..8fc07c6981 100644
--- a/media/ffvpx/libavutil/random_seed.c
+++ b/media/ffvpx/libavutil/random_seed.c
@@ -132,7 +132,8 @@ uint32_t av_get_random_seed(void)
     }
 #endif
 
-#if HAVE_ARC4RANDOM
+/* Don’t use arc4random() on Linux – glibc doesn’t provide it */
+#if HAVE_ARC4RANDOM && !defined(__linux__)
     return arc4random();
 #endif
 
diff --git a/modules/zlib/src/moz.build b/modules/zlib/src/moz.build
index 0ce92da9fb..1acae55bff 100644
--- a/modules/zlib/src/moz.build
+++ b/modules/zlib/src/moz.build
@@ -31,6 +31,15 @@ if CONFIG['INTEL_ARCHITECTURE']:
         SOURCES += [
             'simd_darwin_stub.c',
         ]
+    if CONFIG['OS_ARCH'] == 'Linux':
+        # Keep SIMD/chunkcopy paths disabled on Linux, but provide fallback
+        # helper symbols used by crc32/deflate call sites.
+        DEFINES['ADLER32_SIMD_SSSE3'] = False
+        DEFINES['INFLATE_CHUNK_SIMD_SSE2'] = False
+        DEFINES['CRC32_SIMD_SSE42_PCLMUL'] = False
+        SOURCES += [
+            'simd_darwin_stub.c',
+        ]
     else:
         DEFINES['INFLATE_CHUNK_SIMD_SSE2'] = True
         SOURCES += [
@@ -68,7 +77,8 @@ SOURCES += [
     'zutil.c',
 ]
 
-if CONFIG['CPU_ARCH'] == 'arm' or (CONFIG['INTEL_ARCHITECTURE'] and CONFIG['OS_ARCH'] != 'Darwin'):
+# Enable SIMD inflate only on Windows (WINNT). Disable on Linux, BSD, Darwin, etc.
+if CONFIG['OS_ARCH'] == 'WINNT':
     SOURCES += [
         'inflate_simd.c',
     ]
@@ -77,3 +87,4 @@ else:
         'inflate.c',
     ]
 
+
diff --git a/mozconfigs/uxp-linux-x64 b/mozconfigs/uxp-linux-x64
new file mode 100644
index 0000000000..5a879edb5c
--- /dev/null
+++ b/mozconfigs/uxp-linux-x64
@@ -0,0 +1,70 @@
+# Clear this if not a 64bit build
+_BUILD_64=1
+
+# 16 jobs for 16 cores
+mk_add_options MOZ_MAKE_FLAGS="-j6"
+
+# Set GTK Version to 2 or 3
+_GTK_VERSION=3
+
+export CC=gcc
+export CXX=g++
+export CXXFLAGS="-std=gnu++17 -DNO_SIMD -DHAVE_ARC4RANDOM=0 -DHAVE_ARC4RANDOM_BUF=0"
+export CFLAGS="-std=gnu17 -DNO_SIMD -DHAVE_ARC4RANDOM=0 -DHAVE_ARC4RANDOM_BUF=0"
+
+ac_add_options --enable-application=basilisk
+
+# Updater stuffs
+ac_add_options --disable-updater
+# Enable if update server and signatures are figured out
+#ac_add_options --enable-nss-mar
+
+# Optimization settings
+ac_add_options --disable-accessibility
+ac_add_options --disable-debug
+ac_add_options --disable-debug-js-modules
+ac_add_options --disable-debug-symbols
+ac_add_options --disable-tests
+ac_add_options --enable-devtools
+#ac_add_options --enable-install-strip
+ac_add_options --enable-jemalloc
+ac_add_options --enable-js-lto
+ac_add_options --enable-optimize="-O2 -w"
+ac_add_options --enable-phoenix-extensions
+ac_add_options --enable-release
+ac_add_options --enable-strip
+MOZ_OPTIMIZE=1
+export MOZ_OPTIMIZE=1
+mk_add_options MOZ_OPTIMIZE=1
+export MOZILLA_OFFICIAL=1
+export STRIP_FLAGS="--strip-debug --strip-unneeded"
+
+# Media settings
+ac_add_options --enable-av1
+ac_add_options --enable-jxl
+ac_add_options --enable-raw
+ac_add_options --enable-webrtc
+
+# Client settings
+ac_add_options --disable-crashreporter
+ac_add_options --disable-eme
+ac_add_options --disable-maintenance-service
+ac_add_options --disable-parental-controls
+mk_add_options MOZ_SERVICES_HEALTHREPORT=0
+export CROSS_COMPILE=0
+export MOZ_CRASHREPORTER=0
+export MOZ_DATA_REPORTING=0
+export MOZ_INCLUDE_SOURCE_INFO=1
+export MOZ_REQUIRE_SIGNING=
+export MOZ_SOURCE_CHANGESET=iloveneedingtobodgechangesetfornoreason
+export MOZ_TELEMETRY_REPORTING=
+export MOZ_PACKAGE_JSSHELL=1
+
+# Processor architecture specific build options
+if [ -n "$_BUILD_64" ]; then
+  ac_add_options --x-libraries=/usr/lib64
+else
+  ac_add_options --x-libraries=/usr/lib
+fi
+
+export MOZ_PKG_SPECIAL=gtk$_GTK_VERSION
diff --git a/xpcom/base/nsUUIDGenerator.cpp b/xpcom/base/nsUUIDGenerator.cpp
index 645b34b87e..2f9fd257e2 100644
--- a/xpcom/base/nsUUIDGenerator.cpp
+++ b/xpcom/base/nsUUIDGenerator.cpp
@@ -125,6 +125,31 @@ nsUUIDGenerator::GenerateUUIDInPlace(nsID* aId)
   setstate(mState);
 #endif
 
+#if defined(__linux__)
+  // Linux does not provide arc4random_buf or arc4random.
+  // Use /dev/urandom for secure UUID generation.
+  int fd = open("/dev/urandom", O_RDONLY);
+  if (fd >= 0) {
+    ssize_t n = read(fd, aId, sizeof(nsID));
+    close(fd);
+    if (n == sizeof(nsID)) {
+      return NS_OK;
+    }
+  }
+
+  // Fallback if /dev/urandom fails
+  size_t bytesLeft = sizeof(nsID);
+  while (bytesLeft > 0) {
+    long rval = random();
+    const size_t mRBytes = 4;
+    size_t toCopy = std::min(bytesLeft, mRBytes);
+    memcpy(reinterpret_cast<char*>(aId) + (sizeof(nsID) - bytesLeft),
+           &rval, toCopy);
+    bytesLeft -= toCopy;
+  }
+
+#else
+
 #ifdef HAVE_ARC4RANDOM_BUF
   arc4random_buf(aId, sizeof(nsID));
 #else /* HAVE_ARC4RANDOM_BUF */
@@ -135,8 +160,14 @@ nsUUIDGenerator::GenerateUUIDInPlace(nsID* aId)
     const size_t mRBytes = 4;
 #else
     long rval = random();
+    const size_t mRBytes = 4;
 #endif
-
+    size_t toCopy = std::min(bytesLeft, mRBytes);
+    memcpy(reinterpret_cast<char*>(aId) + (sizeof(nsID) - bytesLeft),
+           &rval, toCopy);
+    bytesLeft -= toCopy;
+  }
+#endif /* HAVE_ARC4RANDOM_BUF */
 
     uint8_t* src = (uint8_t*)&rval;
     // We want to grab the mRBytes least significant bytes of rval, since