Index: lib/asan/asan_mapping.h
===================================================================
--- lib/asan/asan_mapping.h
+++ lib/asan/asan_mapping.h
@@ -140,6 +140,7 @@
 static const u64 kSystemZ_ShadowOffset64 = 1ULL << 52;
 static const u64 kFreeBSD_ShadowOffset32 = 1ULL << 30;  // 0x40000000
 static const u64 kFreeBSD_ShadowOffset64 = 1ULL << 46;  // 0x400000000000
+static const u64 kFreeBSD_AArch64_ShadowOffset64 = 1ULL << 47; // 0x800000000000
 static const u64 kWindowsShadowOffset32 = 3ULL << 28;  // 0x30000000
 
 #define SHADOW_SCALE kDefaultShadowScale
@@ -170,6 +171,8 @@
 #    else
 #      define SHADOW_OFFSET __asan_shadow_memory_dynamic_address
 #    endif
+#  elif defined(__aarch64__) && SANITIZER_FREEBSD
+#    define SHADOW_OFFSET kFreeBSD_AArch64_ShadowOffset64
 #  elif defined(__aarch64__)
 #    define SHADOW_OFFSET kAArch64_ShadowOffset64
 #  elif defined(__powerpc64__)
Index: lib/sanitizer_common/sanitizer_linux.cc
===================================================================
--- lib/sanitizer_common/sanitizer_linux.cc
+++ lib/sanitizer_common/sanitizer_linux.cc
@@ -1058,7 +1058,7 @@
                        : "memory", "$29" );
   return res;
 }
-#elif defined(__aarch64__)
+#elif defined(__aarch64__) && SANITIZER_LINUX
 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
                     int *parent_tidptr, void *newtls, int *child_tidptr) {
   long long res;
@@ -1433,6 +1433,11 @@
 #endif
 
 #if defined(__aarch64__)
+# if SANITIZER_FREEBSD
+static bool Aarch64GetESR(ucontext_t *ucontext, u64 *esr) {
+  return false;
+}
+#else
 // Android headers in the older NDK releases miss this definition.
 struct __sanitizer_esr_context {
   struct _aarch64_ctx head;
@@ -1454,6 +1459,7 @@
   return false;
 }
 #endif
+#endif
 
 SignalContext::WriteFlag SignalContext::GetWriteFlag(void *context) {
   ucontext_t *ucontext = (ucontext_t *)context;
@@ -1491,10 +1497,17 @@
   *bp = ucontext->uc_mcontext.arm_fp;
   *sp = ucontext->uc_mcontext.arm_sp;
 #elif defined(__aarch64__)
+# if SANITIZER_FREEBSD
+  ucontext_t *ucontext = (ucontext_t*)context;
+  *pc = ucontext->uc_mcontext.mc_gpregs.gp_elr;
+  *bp = ucontext->uc_mcontext.mc_gpregs.gp_x[29];
+  *sp = ucontext->uc_mcontext.mc_gpregs.gp_sp;
+# else
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.pc;
   *bp = ucontext->uc_mcontext.regs[29];
   *sp = ucontext->uc_mcontext.sp;
+#endif
 #elif defined(__hppa__)
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.sc_iaoq[0];
Index: lib/sanitizer_common/sanitizer_linux_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_linux_libcdep.cc
+++ lib/sanitizer_common/sanitizer_linux_libcdep.cc
@@ -326,6 +326,8 @@
 # elif defined(__x86_64__)
   // sysarch(AMD64_GET_FSBASE, segbase);
   __asm __volatile("movq %%fs:0, %0" : "=r" (segbase));
+# elif defined(__aarch64__)
+  __asm __volatile("mrs %0, tpidr_el0" : "=&r" (segbase));
 # else
 #  error "unsupported CPU arch for FreeBSD platform"
 # endif
Index: lib/sanitizer_common/sanitizer_platform_limits_posix.cc
===================================================================
--- lib/sanitizer_common/sanitizer_platform_limits_posix.cc
+++ lib/sanitizer_common/sanitizer_platform_limits_posix.cc
@@ -118,7 +118,8 @@
 #if SANITIZER_LINUX || SANITIZER_FREEBSD
 # include <utime.h>
 # include <sys/ptrace.h>
-# if defined(__mips64) || defined(__aarch64__) || defined(__arm__)
+# if SANITIZER_LINUX && (defined(__mips64) || defined(__aarch64__) || \
+     defined(__arm__))
 #  include <asm/ptrace.h>
 #  ifdef __arm__
 typedef struct user_fpregs elf_fpregset_t;
Index: lib/sanitizer_common/sanitizer_syscall_generic.inc
===================================================================
--- lib/sanitizer_common/sanitizer_syscall_generic.inc
+++ lib/sanitizer_common/sanitizer_syscall_generic.inc
@@ -17,7 +17,8 @@
 # define SYSCALL(name) __NR_ ## name
 #endif
 
-#if (SANITIZER_FREEBSD || SANITIZER_MAC) && defined(__x86_64__)
+#if (SANITIZER_FREEBSD || SANITIZER_MAC) && (defined(__x86_64__) || \
+    defined(__aarch64__))
 # define internal_syscall __syscall
 # else
 # define internal_syscall syscall