diff --git a/clang/cmake/caches/Fuchsia-stage2.cmake b/clang/cmake/caches/Fuchsia-stage2.cmake
--- a/clang/cmake/caches/Fuchsia-stage2.cmake
+++ b/clang/cmake/caches/Fuchsia-stage2.cmake
@@ -237,7 +237,37 @@
     list(APPEND RUNTIME_BUILD_ID_LINK "${target}-unknown-fuchsia")
   endforeach()
 
-  set(LLVM_RUNTIME_MULTILIBS "asan;noexcept;asan+noexcept;relative-vtables;relative-vtables+noexcept;relative-vtables+asan;relative-vtables+asan+noexcept" CACHE STRING "")
+  # HWAsan
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan_LLVM_BUILD_COMPILER_RT OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan_LLVM_USE_SANITIZER "HWAddress" CACHE STRING "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan_LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan_LLVM_BUILD_COMPILER_RT OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan_LLVM_USE_SANITIZER "HWAddress" CACHE STRING "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan_LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan_CMAKE_CXX_FLAGS "${RUNTIMES_${target}-unknown-fuchsia+relative-vtables+hwasan_CMAKE_CXX_FLAGS} -Xclang -fexperimental-relative-c++-abi-vtables" CACHE STRING "")
+
+  # HWASan+noexcept
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan+noexcept_LLVM_BUILD_COMPILER_RT OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan+noexcept_LLVM_USE_SANITIZER "HWAddress" CACHE STRING "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan+noexcept_LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan+noexcept_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan+noexcept_LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+hwasan+noexcept_LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan+noexcept_LLVM_BUILD_COMPILER_RT OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan+noexcept_LLVM_USE_SANITIZER "HWAddress" CACHE STRING "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan+noexcept_LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan+noexcept_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan+noexcept_LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan+noexcept_LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+  set(RUNTIMES_aarch64-unknown-fuchsia+relative-vtables+hwasan+noexcept_CMAKE_CXX_FLAGS "${RUNTIMES_${target}-unknown-fuchsia+relative-vtables+hwasan+noexcept_CMAKE_CXX_FLAGS} -Xclang -fexperimental-relative-c++-abi-vtables" CACHE STRING "")
+
+  set(LLVM_RUNTIME_MULTILIBS
+      "asan;noexcept;asan+noexcept;relative-vtables;relative-vtables+noexcept;relative-vtables+asan;relative-vtables+asan+noexcept;hwasan;hwasan+noexcept;relative-vtables+hwasan;relative-vtables+hwasan+noexcept" CACHE STRING "")
+
   set(LLVM_RUNTIME_MULTILIB_asan_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_asan+noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
@@ -245,6 +275,10 @@
   set(LLVM_RUNTIME_MULTILIB_relative-vtables+noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_relative-vtables+asan_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_relative-vtables+asan+noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
+  set(LLVM_RUNTIME_MULTILIB_hwasan_TARGETS "aarch64-unknown-fuchsia" CACHE STRING "")
+  set(LLVM_RUNTIME_MULTILIB_hwasan+noexcept_TARGETS "aarch64-unknown-fuchsia" CACHE STRING "")
+  set(LLVM_RUNTIME_MULTILIB_relative-vtables+hwasan_TARGETS "aarch64-unknown-fuchsia" CACHE STRING "")
+  set(LLVM_RUNTIME_MULTILIB_relative-vtables+hwasan+noexcept_TARGETS "aarch64-unknown-fuchsia" CACHE STRING "")
 endif()
 
 set(LLVM_BUILTIN_TARGETS "${BUILTIN_TARGETS}" CACHE STRING "")
diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -702,7 +702,7 @@
 endif()
 
 if (COMPILER_RT_HAS_SANITIZER_COMMON AND HWASAN_SUPPORTED_ARCH AND
-    OS_NAME MATCHES "Linux|Android")
+    OS_NAME MATCHES "Linux|Android|Fuchsia")
   set(COMPILER_RT_HAS_HWASAN TRUE)
 else()
   set(COMPILER_RT_HAS_HWASAN FALSE)
diff --git a/compiler-rt/lib/hwasan/CMakeLists.txt b/compiler-rt/lib/hwasan/CMakeLists.txt
--- a/compiler-rt/lib/hwasan/CMakeLists.txt
+++ b/compiler-rt/lib/hwasan/CMakeLists.txt
@@ -6,6 +6,7 @@
   hwasan_allocator.cpp
   hwasan_dynamic_shadow.cpp
   hwasan_exceptions.cpp
+  hwasan_fuchsia.cpp
   hwasan_globals.cpp
   hwasan_interceptors.cpp
   hwasan_interceptors_vfork.S
@@ -41,7 +42,11 @@
   )
 
 set(HWASAN_DEFINITIONS)
-append_list_if(COMPILER_RT_HWASAN_WITH_INTERCEPTORS HWASAN_WITH_INTERCEPTORS=1 HWASAN_DEFINITIONS)
+if (NOT FUCHSIA)
+  append_list_if(COMPILER_RT_HWASAN_WITH_INTERCEPTORS HWASAN_WITH_INTERCEPTORS=1 HWASAN_DEFINITIONS)
+else()
+  list(APPEND HWASAN_DEFINITIONS HWASAN_REPLACE_OPERATORS_NEW_AND_DELETE=1)
+endif()
 
 set(HWASAN_RTL_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 append_rtti_flag(OFF HWASAN_RTL_CFLAGS)
diff --git a/compiler-rt/lib/hwasan/hwasan.h b/compiler-rt/lib/hwasan/hwasan.h
--- a/compiler-rt/lib/hwasan/hwasan.h
+++ b/compiler-rt/lib/hwasan/hwasan.h
@@ -138,6 +138,7 @@
 
 void HwasanTSDInit();
 void HwasanTSDThreadInit();
+void HwasanAtExit(void);
 
 void HwasanOnDeadlySignal(int signo, void *info, void *context);
 
@@ -147,6 +148,21 @@
 
 void AndroidTestTlsSlot();
 
+// This is a compiler-generated struct that can be shared between hwasan
+// implementations.
+struct AccessInfo {
+  uptr addr;
+  uptr size;
+  bool is_store;
+  bool is_load;
+  bool recover;
+};
+
+void HandleTagMismatch(AccessInfo ai, uptr pc, uptr frame,
+                       void *uc, uptr *registers_frame = nullptr);
+void HwasanTagMismatch(uptr addr, uptr access_info,
+                       uptr *registers_frame, size_t outsize);
+
 }  // namespace __hwasan
 
 #define HWASAN_MALLOC_HOOK(ptr, size)       \
diff --git a/compiler-rt/lib/hwasan/hwasan.cpp b/compiler-rt/lib/hwasan/hwasan.cpp
--- a/compiler-rt/lib/hwasan/hwasan.cpp
+++ b/compiler-rt/lib/hwasan/hwasan.cpp
@@ -180,6 +180,58 @@
 void UpdateMemoryUsage() {}
 #endif
 
+void HwasanAtExit(void) {
+  if (common_flags()->print_module_map)
+    DumpProcessMap();
+  if (flags()->print_stats && (flags()->atexit || hwasan_report_count > 0))
+    ReportStats();
+  if (hwasan_report_count > 0) {
+    // ReportAtExitStatistics();
+    if (common_flags()->exitcode)
+      internal__exit(common_flags()->exitcode);
+  }
+}
+
+void HandleTagMismatch(AccessInfo ai, uptr pc, uptr frame,
+                       void *uc, uptr *registers_frame) {
+  InternalMmapVector<BufferedStackTrace> stack_buffer(1);
+  BufferedStackTrace *stack = stack_buffer.data();
+  stack->Reset();
+  stack->Unwind(pc, frame, uc, common_flags()->fast_unwind_on_fatal);
+
+  // The second stack frame contains the failure __hwasan_check function, as
+  // we have a stack frame for the registers saved in __hwasan_tag_mismatch that
+  // we wish to ignore. This (currently) only occurs on AArch64, as x64
+  // implementations use SIGTRAP to implement the failure, and thus do not go
+  // through the stack saver.
+  if (registers_frame && stack->trace && stack->size > 0) {
+    stack->trace++;
+    stack->size--;
+  }
+
+  bool fatal = flags()->halt_on_error || !ai.recover;
+  ReportTagMismatch(stack, ai.addr, ai.size, ai.is_store, fatal,
+                    registers_frame);
+}
+
+void HwasanTagMismatch(uptr addr, uptr access_info,
+                       uptr *registers_frame, size_t outsize) {
+  AccessInfo ai;
+  ai.is_store = access_info & 0x10;
+  ai.is_load = !ai.is_store;
+  ai.recover = access_info & 0x20;
+  ai.addr = addr;
+  if ((access_info & 0xf) == 0xf)
+    ai.size = outsize;
+  else
+    ai.size = 1 << (access_info & 0xf);
+
+  HandleTagMismatch(ai, (uptr)__builtin_return_address(0),
+                    (uptr)__builtin_frame_address(0), nullptr,
+                    registers_frame);
+  __builtin_unreachable();
+}
+
 } // namespace __hwasan
 
 using namespace __hwasan;
diff --git a/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp b/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp
--- a/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp
@@ -21,7 +21,9 @@
 #include "hwasan_mapping.h"
 #include "hwasan_thread_list.h"
 #include "sanitizer_common/sanitizer_common.h"
+#if SANITIZER_POSIX
 #include "sanitizer_common/sanitizer_posix.h"
+#endif
 
 // The code in this file needs to run in an unrelocated binary. It should not
 // access any external symbol, including its own non-hidden globals.
@@ -113,6 +115,14 @@
 }
 
 }  // namespace __hwasan
+#elif SANITIZER_FUCHSIA
+
+namespace __hwasan {
+
+void InitShadowGOT() {}
+
+}  // namespace __hwasan
+
 #else
 namespace __hwasan {
 
diff --git a/compiler-rt/lib/hwasan/hwasan_fuchsia.cpp b/compiler-rt/lib/hwasan/hwasan_fuchsia.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/lib/hwasan/hwasan_fuchsia.cpp
@@ -0,0 +1,120 @@
+//===-- hwasan_fuchsia.cpp --------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file is a part of HWAddressSanitizer and contains Fuchsia-specific
+/// code.
+///
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_fuchsia.h"
+#if SANITIZER_FUCHSIA
+
+#include "hwasan.h"
+#include "hwasan_interface_internal.h"
+#include "hwasan_thread.h"
+#include "hwasan_report.h"
+#include "hwasan_thread_list.h"
+
+SANITIZER_INTERFACE_ATTRIBUTE
+THREADLOCAL uptr __hwasan_tls;
+
+namespace __hwasan {
+
+uptr kHighMemEnd;
+uptr kHighMemBeg;
+uptr kAliasRegionStart = 0;  // Always 0 on non-x86.
+
+bool InitShadow() {
+  __hwasan_shadow_memory_dynamic_address = 0;
+
+  // This initializes __sanitizer::ShadowBounds.
+  kHighMemEnd = GetMaxUserVirtualAddress();
+  kHighMemBeg = __sanitizer::ShadowBounds.shadow_limit;
+
+  CHECK_EQ(kHighMemEnd, __sanitizer::ShadowBounds.memory_limit - 1);
+  CHECK_EQ(kHighMemBeg, __sanitizer::ShadowBounds.shadow_limit);
+  CHECK_NE(kHighMemBeg, 0);
+
+  return true;
+}
+
+void InitThreads() {
+  uptr alloc_size = UINT64_C(1) << kShadowBaseAlignment;
+  uptr thread_start = reinterpret_cast<uptr>(
+      MmapAlignedOrDieOnFatalError(alloc_size, alloc_size, __func__));
+  InitThreadList(thread_start, thread_start + alloc_size);
+}
+
+void InitPrctl() {}
+
+bool MemIsApp(uptr p) {
+  CHECK(GetTagFromPointer(p) == 0);
+  return kHighMemBeg <= p && p <= kHighMemEnd;
+}
+
+void InstallAtExitHandler() {}
+
+// ---------------------- TSD ---------------- {{{
+
+extern "C" {
+void __sanitizer_thread_start_hook(void *hook, thrd_t self) {
+  hwasanThreadList().CreateCurrentThread()->InitRandomState();
+}
+
+void __sanitizer_thread_exit_hook(void *hook, thrd_t self) {
+  Thread *t = GetCurrentThread();
+  // Make sure that signal handler can not see a stale current thread pointer.
+  atomic_signal_fence(memory_order_seq_cst);
+  if (t)
+    hwasanThreadList().ReleaseThread(t);
+}
+
+void __sanitizer_exit() {
+  __hwasan::HwasanAtExit();
+}
+}  // extern "C"
+
+void HwasanTSDInit() {}
+void HwasanTSDThreadInit() {}
+
+static THREADLOCAL uptr __hwasan_tls;
+
+uptr *GetCurrentThreadLongPtr() {
+  return &__hwasan_tls;
+}
+
+void AndroidTestTlsSlot() {}
+
+Thread *GetCurrentThread() {
+  uptr *ThreadLongPtr = GetCurrentThreadLongPtr();
+  if (UNLIKELY(*ThreadLongPtr == 0))
+    return nullptr;
+  auto *R = (StackAllocationsRingBuffer *)ThreadLongPtr;
+  return hwasanThreadList().GetThreadByBufferAddress((uptr)R->Next());
+}
+
+// Entry point stub for interoperability between __hwasan_tag_mismatch (ASM) and
+// the rest of the mismatch handling code (C++).
+extern "C" void __hwasan_tag_mismatch4(uptr addr, uptr access_info,
+                                       uptr *registers_frame, size_t outsize) {
+  __hwasan::HwasanTagMismatch(addr, access_info, registers_frame, outsize);
+}
+
+static void OnStackUnwind(const SignalContext &sig, const void *,
+                          BufferedStackTrace *stack) {
+  stack->Unwind(StackTrace::GetNextInstructionPc(sig.pc), sig.bp, sig.context,
+                common_flags()->fast_unwind_on_fatal);
+}
+
+// TODO: Do we need this?
+void HwasanOnDeadlySignal(int signo, void *info, void *context) {}
+
+}  // namespace __hwasan
+
+#endif  // SANITIZER_FUCHSIA
diff --git a/compiler-rt/lib/hwasan/hwasan_interceptors.cpp b/compiler-rt/lib/hwasan/hwasan_interceptors.cpp
--- a/compiler-rt/lib/hwasan/hwasan_interceptors.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_interceptors.cpp
@@ -21,6 +21,7 @@
 #include "hwasan_thread.h"
 #include "hwasan_poisoning.h"
 #include "hwasan_report.h"
+#include "sanitizer_common/sanitizer_platform_limits_fuchsia.h"
 #include "sanitizer_common/sanitizer_platform_limits_posix.h"
 #include "sanitizer_common/sanitizer_allocator.h"
 #include "sanitizer_common/sanitizer_allocator_interface.h"
@@ -303,6 +304,7 @@
 
 #endif // HWASAN_WITH_INTERCEPTORS && __aarch64__
 
+#if HWASAN_WITH_INTERCEPTORS
 static void BeforeFork() {
   StackDepotLockAll();
 }
@@ -318,6 +320,7 @@
   AfterFork();
   return pid;
 }
+#endif  // HWASAN_WITH_INTERCEPTORS
 
 namespace __hwasan {
 
@@ -334,9 +337,9 @@
   static int inited = 0;
   CHECK_EQ(inited, 0);
 
+#if HWASAN_WITH_INTERCEPTORS
   INTERCEPT_FUNCTION(fork);
 
-#if HWASAN_WITH_INTERCEPTORS
 #if defined(__linux__)
   INTERCEPT_FUNCTION(vfork);
 #endif  // __linux__
diff --git a/compiler-rt/lib/hwasan/hwasan_interface_internal.h b/compiler-rt/lib/hwasan/hwasan_interface_internal.h
--- a/compiler-rt/lib/hwasan/hwasan_interface_internal.h
+++ b/compiler-rt/lib/hwasan/hwasan_interface_internal.h
@@ -15,6 +15,7 @@
 #define HWASAN_INTERFACE_INTERNAL_H
 
 #include "sanitizer_common/sanitizer_internal_defs.h"
+#include "sanitizer_common/sanitizer_platform_limits_fuchsia.h"
 #include "sanitizer_common/sanitizer_platform_limits_posix.h"
 #include <link.h>
 
diff --git a/compiler-rt/lib/hwasan/hwasan_linux.cpp b/compiler-rt/lib/hwasan/hwasan_linux.cpp
--- a/compiler-rt/lib/hwasan/hwasan_linux.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_linux.cpp
@@ -242,18 +242,6 @@
   return p >= kHighMemStart || (p >= kLowMemStart && p <= kLowMemEnd);
 }
 
-static void HwasanAtExit(void) {
-  if (common_flags()->print_module_map)
-    DumpProcessMap();
-  if (flags()->print_stats && (flags()->atexit || hwasan_report_count > 0))
-    ReportStats();
-  if (hwasan_report_count > 0) {
-    // ReportAtExitStatistics();
-    if (common_flags()->exitcode)
-      internal__exit(common_flags()->exitcode);
-  }
-}
-
 void InstallAtExitHandler() {
   atexit(HwasanAtExit);
 }
@@ -338,14 +326,6 @@
   return hwasanThreadList().GetThreadByBufferAddress((uptr)R->Next());
 }
 
-struct AccessInfo {
-  uptr addr;
-  uptr size;
-  bool is_store;
-  bool is_load;
-  bool recover;
-};
-
 static AccessInfo GetAccessInfo(siginfo_t *info, ucontext_t *uc) {
   // Access type is passed in a platform dependent way (see below) and encoded
   // as 0xXY, where X&1 is 1 for store, 0 for load, and X&2 is 1 if the error is
@@ -396,28 +376,6 @@
   return AccessInfo{addr, size, is_store, !is_store, recover};
 }
 
-static void HandleTagMismatch(AccessInfo ai, uptr pc, uptr frame,
-                              ucontext_t *uc, uptr *registers_frame = nullptr) {
-  InternalMmapVector<BufferedStackTrace> stack_buffer(1);
-  BufferedStackTrace *stack = stack_buffer.data();
-  stack->Reset();
-  stack->Unwind(pc, frame, uc, common_flags()->fast_unwind_on_fatal);
-
-  // The second stack frame contains the failure __hwasan_check function, as
-  // we have a stack frame for the registers saved in __hwasan_tag_mismatch that
-  // we wish to ignore. This (currently) only occurs on AArch64, as x64
-  // implementations use SIGTRAP to implement the failure, and thus do not go
-  // through the stack saver.
-  if (registers_frame && stack->trace && stack->size > 0) {
-    stack->trace++;
-    stack->size--;
-  }
-
-  bool fatal = flags()->halt_on_error || !ai.recover;
-  ReportTagMismatch(stack, ai.addr, ai.size, ai.is_store, fatal,
-                    registers_frame);
-}
-
 static bool HwasanOnSIGTRAP(int signo, siginfo_t *info, ucontext_t *uc) {
   AccessInfo ai = GetAccessInfo(info, uc);
   if (!ai.is_store && !ai.is_load)
@@ -457,20 +415,7 @@
 // rest of the mismatch handling code (C++).
 void __hwasan_tag_mismatch4(uptr addr, uptr access_info, uptr *registers_frame,
                             size_t outsize) {
-  __hwasan::AccessInfo ai;
-  ai.is_store = access_info & 0x10;
-  ai.is_load = !ai.is_store;
-  ai.recover = access_info & 0x20;
-  ai.addr = addr;
-  if ((access_info & 0xf) == 0xf)
-    ai.size = outsize;
-  else
-    ai.size = 1 << (access_info & 0xf);
-
-  __hwasan::HandleTagMismatch(ai, (uptr)__builtin_return_address(0),
-                              (uptr)__builtin_frame_address(0), nullptr,
-                              registers_frame);
-  __builtin_unreachable();
+  __hwasan::HwasanTagMismatch(addr, access_info, registers_frame, outsize);
 }
 
 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD
diff --git a/compiler-rt/lib/hwasan/hwasan_poisoning.cpp b/compiler-rt/lib/hwasan/hwasan_poisoning.cpp
--- a/compiler-rt/lib/hwasan/hwasan_poisoning.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_poisoning.cpp
@@ -22,6 +22,10 @@
 uptr TagMemoryAligned(uptr p, uptr size, tag_t tag) {
   CHECK(IsAligned(p, kShadowAlignment));
   CHECK(IsAligned(size, kShadowAlignment));
+#if SANITIZER_FUCHSIA
+  __sanitizer_fill_shadow(p, size, tag,
+                          common_flags()->clear_shadow_mmap_threshold);
+#else
   uptr shadow_start = MemToShadow(p);
   uptr shadow_size = MemToShadowSize(size);
 
@@ -40,6 +44,7 @@
   } else {
     internal_memset((void *)shadow_start, tag, shadow_size);
   }
+#endif
   return AddTagToPointer(p, tag);
 }
 
diff --git a/compiler-rt/lib/hwasan/hwasan_thread.cpp b/compiler-rt/lib/hwasan/hwasan_thread.cpp
--- a/compiler-rt/lib/hwasan/hwasan_thread.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_thread.cpp
@@ -51,12 +51,18 @@
   // ScopedTaggingDisable needs GetCurrentThread to be set up.
   ScopedTaggingDisabler disabler;
 
+#if !SANITIZER_FUCHSIA
   uptr tls_size;
   uptr stack_size;
   GetThreadStackAndTls(IsMainThread(), &stack_bottom_, &stack_size, &tls_begin_,
                        &tls_size);
   stack_top_ = stack_bottom_ + stack_size;
   tls_end_ = tls_begin_ + tls_size;
+#else
+  __sanitizer::GetThreadStackTopAndBottom(true, &stack_top_,
+                                          &stack_bottom_);
+  tls_end_ = tls_begin_ = 0;
+#endif
 
   if (stack_bottom_) {
     int local;
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_fuchsia.h b/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_fuchsia.h
new file mode 100644
--- /dev/null
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_fuchsia.h
@@ -0,0 +1,25 @@
+//===-- sanitizer_platform_limits_fuchsia.h -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of Sanitizer common code.
+//
+// Sizes and layouts of platform-specific Fuchsia data structures.
+//===----------------------------------------------------------------------===//
+
+#ifndef SANITIZER_PLATFORM_LIMITS_FUCHSIA_H
+#define SANITIZER_PLATFORM_LIMITS_FUCHSIA_H
+
+#if SANITIZER_FUCHSIA
+
+namespace __sanitizer {
+struct __sanitizer_struct_mallinfo {};
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_FUCHSIA
+
+#endif
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_markup.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_markup.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_markup.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_markup.cpp
@@ -54,6 +54,10 @@
   return false;
 }
 
+// This is mainly used by hwasan for online symbolization. This isn't needed
+// since hwasan can always just dump stack frames for offline symbolization.
+bool Symbolizer::SymbolizeFrame(uptr addr, FrameInfo *info) { return false; }
+
 // This is used in some places for suppression checking, which we
 // don't really support for Fuchsia.  It's also used in UBSan to
 // identify a PC location to a function name, so we always fill in