diff --git a/ARM.CMSIS-Compiler.pdsc b/ARM.CMSIS-Compiler.pdsc
index c16f249..e0e3b3e 100644
--- a/ARM.CMSIS-Compiler.pdsc
+++ b/ARM.CMSIS-Compiler.pdsc
@@ -15,6 +15,8 @@
   <releases>
     <release version="2.2.1-dev">
       Active Development ...
+      CLANG:
+      - Added standard I/O stream support for LLVM-libc
     </release>
   </releases>
 
@@ -245,7 +247,7 @@
         <file category="header"  name="config/stdio_cmsis_uart_config.h" attr="config" version="1.0.0" condition="STDIO UART CMSIS"/>
       </files>
     </component>
-    <component Cclass="CMSIS-Compiler" Cgroup="CORE" Cversion="1.2.0" condition="CLANG CortexDevice">
+    <component Cclass="CMSIS-Compiler" Cgroup="CORE" Cversion="1.3.0" condition="CLANG CortexDevice">
       <description>Standard C Library Retarget Core</description>
       <files>
         <file category="sourceC" name="source/core/clang/retarget_syscalls.c"/>
diff --git a/source/core/clang/retarget_syscalls.c b/source/core/clang/retarget_syscalls.c
index 96260e3..834b74a 100644
--- a/source/core/clang/retarget_syscalls.c
+++ b/source/core/clang/retarget_syscalls.c
@@ -41,6 +41,181 @@
 #endif
 #endif
 
+#ifndef STDIN_ECHO
+#define STDIN_ECHO      0       /* STDIN: echo to STDOUT */
+#endif
+#ifndef STDOUT_CR_LF
+#define STDOUT_CR_LF    0       /* STDOUT: add CR for LF */
+#endif
+#ifndef STDERR_CR_LF
+#define STDERR_CR_LF    0       /* STDERR: add CR for LF */
+#endif
+
+#if defined(__LLVM_LIBC__)
+
+/* Symbols used as cookie values to identify standard I/O stream */
+void *__llvm_libc_stdin_cookie  = NULL;
+void *__llvm_libc_stdout_cookie = NULL;
+void *__llvm_libc_stderr_cookie = NULL;
+
+/**
+  Write bytes to a standard output stream.
+
+  Called by LLVM-libc for all stdout/stderr writes.  The cookie parameter
+  identifies the target stream: it matches the address of the
+  __llvm_libc_stdout_cookie or __llvm_libc_stderr_cookie symbol.
+
+  \param[in]  cookie  Stream identifier
+  \param[in]  buf     Pointer to data buffer
+  \param[in]  size    Number of bytes to write
+  \return             Number of bytes written, or -1 on error.
+*/
+__attribute__((weak))
+ssize_t __llvm_libc_stdio_write(void *cookie, const char *buf, size_t size) {
+#if (defined(RTE_CMSIS_Compiler_STDOUT) || defined(RTE_CMSIS_Compiler_STDERR))
+  int ch;
+  ssize_t sz = 0;
+  const char *p = buf;
+#else
+  (void)cookie;
+  (void)buf;
+  (void)size;
+#endif
+
+#if defined(RTE_CMSIS_Compiler_STDOUT)
+  if (cookie == &__llvm_libc_stdout_cookie) {
+    while (sz < (ssize_t)size) {
+      ch = *p++;
+#if (STDOUT_CR_LF != 0)
+      if (ch == '\n') {
+        if (stdout_putchar('\r') == -1) {
+          break;
+        }
+      }
+#endif
+      if (stdout_putchar(ch) == -1) {
+        break;
+      }
+      sz++;
+    }
+    return (sz);
+  }
+#endif
+
+#if defined(RTE_CMSIS_Compiler_STDERR)
+  if (cookie == &__llvm_libc_stderr_cookie) {
+    while (sz < (ssize_t)size) {
+      ch = *p++;
+#if (STDERR_CR_LF != 0)
+      if (ch == '\n') {
+        if (stderr_putchar('\r') == -1) {
+          break;
+        }
+      }
+#endif
+      if (stderr_putchar(ch) == -1) {
+        break;
+      }
+      sz++;
+    }
+    return (sz);
+  }
+#endif
+  /* Not implemented */
+  return (-1);
+}
+
+/**
+  Read bytes from stdin.
+
+  Called by LLVM-libc for all stdin reads.  The cookie parameter matches the
+  address of the __llvm_libc_stdin_cookie symbol.
+
+  \param[in]  cookie  Stream identifier
+  \param[out] buf     Pointer to data buffer
+  \param[in]  size    Maximum number of bytes to read
+  \return             Number of bytes read (> 0), 0 on end of input,
+                      or a negative errno value on error.
+*/
+__attribute__((weak))
+ssize_t __llvm_libc_stdio_read(void *cookie, char *buf, size_t size) {
+#if defined(RTE_CMSIS_Compiler_STDIN)
+  int ch;
+  ssize_t sz = 0;
+  char *p = buf;
+#else
+  (void)cookie;
+  (void)buf;
+  (void)size;
+#endif
+
+#if defined(RTE_CMSIS_Compiler_STDIN)
+  if (cookie == &__llvm_libc_stdin_cookie) {
+    while (sz < (ssize_t)size) {
+      ch = stdin_getchar();
+      if (ch < 0) {
+        break;
+      }
+      *p++ = (char)ch;
+#if (STDIN_ECHO != 0)
+      stdout_putchar(ch);
+#endif
+      sz++;
+    }
+    return sz;
+  }
+#endif
+  /* Not implemented */
+  return (-1);
+}
+
+/**
+  Terminate a process.
+
+  Called by LLVM-libc for all process termination. 
+  The status parameter is the exit code passed to the exit() function. This
+  implementation does not support process termination, so it simply enters
+  an infinite loop.
+
+  \param[in]  status  Exit code passed to exit()
+*/
+__attribute__((weak, __noreturn__))
+void __llvm_libc_exit(int status) {
+  (void)status;
+  for (;;) { ; }
+}
+
+/**
+  Set up the exceptions table and enable relevant interrupts.
+
+  This function overrides crt0's _platform_setup_exceptions which sets VTOR
+  to its own minimal 16-entry vector table, breaking device IRQ handlers.
+  Restoring VTOR to the full CMSIS vector table (256 entries) ensures device-
+  specific interrupt vectors are resolved correctly.
+*/
+__attribute__((weak))
+void _platform_setup_exceptions (void) {}
+
+/**
+  Set up the Memory Management Unit and caches.
+
+  This function overrides crt0's _platform_setup_memory which may override settings
+  applied in vendor specific SystemInit.
+*/
+__attribute__((weak))
+void _platform_setup_memory (void) {}
+
+/**
+  Set up architecture extensions that require special initialization.
+
+  This function overrides crt0's _platform_setup_arch_extensions which may override
+  settings applied in vendor specific SystemInit.
+*/
+__attribute__((weak))
+void _platform_setup_arch_extensions (void) {}
+
+#elif defined(__PICOLIBC_VERSION__)
+
 #if defined(RTE_CMSIS_Compiler_STDIN)
 /**
   Get a character from the stdio
@@ -93,7 +268,6 @@ static FILE __stdout = FDEV_SETUP_STREAM(stdout_putc,
 FILE *const stdout = &__stdout;
 #endif
 
-
 #if defined(RTE_CMSIS_Compiler_STDERR)
 /**
   Put a character to the stderr
@@ -125,3 +299,4 @@ __attribute__((weak, __noreturn__))
 void _exit (int status) {
   for(;;){ ; }
 }
+#endif /* __LLVM_LIBC__ */