diff --git a/mozilla/nsprpub/pr/include/md/_linux.cfg b/mozilla/nsprpub/pr/include/md/_linux.cfg
index d0a3beeb125..2fdbf63ee84 100644
--- a/mozilla/nsprpub/pr/include/md/_linux.cfg
+++ b/mozilla/nsprpub/pr/include/md/_linux.cfg
@@ -590,6 +590,59 @@
 #define PR_BYTES_PER_WORD_LOG2   2
 #define PR_BYTES_PER_DWORD_LOG2  3
 
+#elif defined(__aarch64__)
+
+#ifdef __AARCH64EB__
+#undef  IS_LITTLE_ENDIAN
+#define IS_BIG_ENDIAN 1
+#elif defined(__AARCH64EL__)
+#define IS_LITTLE_ENDIAN 1
+#undef  IS_BIG_ENDIAN
+#else
+#error "Unknown Aarch64 endianness."
+#endif
+#define IS_64
+
+#define PR_BYTES_PER_BYTE   1
+#define PR_BYTES_PER_SHORT  2
+#define PR_BYTES_PER_INT    4
+#define PR_BYTES_PER_INT64  8
+#define PR_BYTES_PER_LONG   8
+#define PR_BYTES_PER_FLOAT  4
+#define PR_BYTES_PER_DOUBLE 8
+#define PR_BYTES_PER_WORD   8
+#define PR_BYTES_PER_DWORD  8
+
+#define PR_BITS_PER_BYTE    8
+#define PR_BITS_PER_SHORT   16
+#define PR_BITS_PER_INT     32
+#define PR_BITS_PER_INT64   64
+#define PR_BITS_PER_LONG    64
+#define PR_BITS_PER_FLOAT   32
+#define PR_BITS_PER_DOUBLE  64
+#define PR_BITS_PER_WORD    64
+
+#define PR_BITS_PER_BYTE_LOG2   3
+#define PR_BITS_PER_SHORT_LOG2  4
+#define PR_BITS_PER_INT_LOG2    5
+#define PR_BITS_PER_INT64_LOG2  6
+#define PR_BITS_PER_LONG_LOG2   6
+#define PR_BITS_PER_FLOAT_LOG2  5
+#define PR_BITS_PER_DOUBLE_LOG2 6
+#define PR_BITS_PER_WORD_LOG2   6
+
+#define PR_ALIGN_OF_SHORT   2
+#define PR_ALIGN_OF_INT     4
+#define PR_ALIGN_OF_LONG    8
+#define PR_ALIGN_OF_INT64   8
+#define PR_ALIGN_OF_FLOAT   4
+#define PR_ALIGN_OF_DOUBLE  8
+#define PR_ALIGN_OF_POINTER 8
+#define PR_ALIGN_OF_WORD    8
+
+#define PR_BYTES_PER_WORD_LOG2  3
+#define PR_BYTES_PER_DWORD_LOG2 3
+
 #elif defined(__hppa__)
 
 #undef  IS_LITTLE_ENDIAN
diff --git a/mozilla/nsprpub/pr/include/md/_linux.h b/mozilla/nsprpub/pr/include/md/_linux.h
index 4992b773507..906822fb841 100644
--- a/mozilla/nsprpub/pr/include/md/_linux.h
+++ b/mozilla/nsprpub/pr/include/md/_linux.h
@@ -41,6 +41,8 @@
 #define _PR_SI_ARCHITECTURE "mips"
 #elif defined(__arm__)
 #define _PR_SI_ARCHITECTURE "arm"
+#elif defined(__aarch64__)
+#define _PR_SI_ARCHITECTURE "aarch64"
 #elif defined(__hppa__)
 #define _PR_SI_ARCHITECTURE "hppa"
 #elif defined(__s390x__)
@@ -63,6 +65,10 @@
 #define _MD_DEFAULT_STACK_SIZE	65536L
 #define _MD_MMAP_FLAGS          MAP_PRIVATE
 
+#if defined(__aarch64__)
+#define _MD_MINIMUM_STACK_SIZE  0x20000
+#endif
+
 #undef	HAVE_STACK_GROWING_UP
 
 /*
@@ -186,7 +192,7 @@ extern PRInt32 _PR_ppc_AtomicSet(PRInt32 *val, PRInt32 newval);
 })
 #endif
 
-#if defined(__arm__)
+#if defined(__arm__) || defined(__aarch64__)
 #if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
 /* Use GCC built-in functions */
 #define _PR_HAVE_ATOMIC_OPS