diff --git a/lldb/tools/debugserver/source/RNBRemote.cpp b/lldb/tools/debugserver/source/RNBRemote.cpp
index 586336a21b6..996ce2f96cf 100644
--- a/lldb/tools/debugserver/source/RNBRemote.cpp
+++ b/lldb/tools/debugserver/source/RNBRemote.cpp
@@ -176,7 +176,7 @@ RNBRemote::RNBRemote()
       m_extended_mode(false), m_noack_mode(false),
       m_thread_suffix_supported(false), m_list_threads_in_stop_reply(false),
       m_compression_minsize(384), m_enable_compression_next_send_packet(false),
-      m_compression_mode(compression_types::none) {
+      m_compression_mode(compression_types::none), m_a_packet_base16(false) {
   DNBLogThreadedIf(LOG_RNB_REMOTE, "%s", __PRETTY_FUNCTION__);
   CreatePacketTable();
 }
@@ -1530,8 +1530,9 @@ void RNBRemote::NotifyThatProcessStopped(void) {
 
  6,0,676462,4,1,2d71,10,2,612e6f7574
 
- Note that "argnum" and "arglen" are numbers in base 10.  Again, that's
- not documented either way but I'm assuming it's so.  */
+ lldb would use base 10 for "argnum" and "arglen" but that is incorrect.
+ Default behavior is currently still base10, but when m_a_packet_base16 is
+ via the qSupported packet negotiation, use base16. */
 
 rnb_err_t RNBRemote::HandlePacket_A(const char *p) {
   if (p == NULL || *p == '\0') {
@@ -1548,6 +1549,7 @@ rnb_err_t RNBRemote::HandlePacket_A(const char *p) {
    2nd arg has to be non-const which makes it problematic to step
    through the string easily.  */
   char *buf = const_cast<char *>(p);
+  const char *end_of_buf = buf + strlen(buf);
 
   RNBContext &ctx = Context();
 
@@ -1557,7 +1559,7 @@ rnb_err_t RNBRemote::HandlePacket_A(const char *p) {
     char *c;
 
     errno = 0;
-    arglen = strtoul(buf, &c, 10);
+    arglen = strtoul(buf, &c, m_a_packet_base16 ? 16 : 10);
     if (errno != 0 && arglen == 0) {
       return HandlePacket_ILLFORMED(__FILE__, __LINE__, p,
                                     "arglen not a number on 'A' pkt");
@@ -1569,7 +1571,7 @@ rnb_err_t RNBRemote::HandlePacket_A(const char *p) {
     buf = c + 1;
 
     errno = 0;
-    argnum = strtoul(buf, &c, 10);
+    argnum = strtoul(buf, &c, m_a_packet_base16 ? 16 : 10);
     if (errno != 0 && argnum == 0) {
       return HandlePacket_ILLFORMED(__FILE__, __LINE__, p,
                                     "argnum not a number on 'A' pkt");
@@ -1582,6 +1584,10 @@ rnb_err_t RNBRemote::HandlePacket_A(const char *p) {
 
     c = buf;
     buf = buf + arglen;
+
+    if (buf > end_of_buf)
+      break;
+
     while (c < buf && *c != '\0' && c + 1 < buf && *(c + 1) != '\0') {
       char smallbuf[3];
       smallbuf[0] = *c;
@@ -3651,8 +3657,12 @@ rnb_err_t RNBRemote::HandlePacket_qSupported(const char *p) {
     snprintf(numbuf, sizeof(numbuf), "%zu", m_compression_minsize);
     numbuf[sizeof(numbuf) - 1] = '\0';
     strcat(buf, numbuf);
-  } 
+  }
 
+  if (strstr(p, "a-packet-base16")) {
+    m_a_packet_base16 = true;
+    strcat(buf, ";a-packet-base16+");
+  }
   return SendPacket(buf);
 }
 
diff --git a/lldb/tools/debugserver/source/RNBRemote.h b/lldb/tools/debugserver/source/RNBRemote.h
index b0535372a32..e3daa6e1a5c 100644
--- a/lldb/tools/debugserver/source/RNBRemote.h
+++ b/lldb/tools/debugserver/source/RNBRemote.h
@@ -405,6 +405,8 @@ protected:
   size_t m_compression_minsize; // only packets larger than this size will be
                                 // compressed
   bool m_enable_compression_next_send_packet;
+  bool m_a_packet_base16; // A packet arguments are base 16 (correct) versus
+                          // (old buggy) base 10
 
   compression_types m_compression_mode;
 };