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
@@ -625,7 +625,7 @@
 endif()
 
 if (COMPILER_RT_HAS_SANITIZER_COMMON AND LSAN_SUPPORTED_ARCH AND
-    OS_NAME MATCHES "Darwin|Linux|NetBSD")
+    OS_NAME MATCHES "Darwin|Linux|NetBSD|Fuchsia")
   set(COMPILER_RT_HAS_LSAN TRUE)
 else()
   set(COMPILER_RT_HAS_LSAN FALSE)
diff --git a/compiler-rt/lib/lsan/CMakeLists.txt b/compiler-rt/lib/lsan/CMakeLists.txt
--- a/compiler-rt/lib/lsan/CMakeLists.txt
+++ b/compiler-rt/lib/lsan/CMakeLists.txt
@@ -5,6 +5,7 @@
 
 set(LSAN_COMMON_SOURCES
   lsan_common.cpp
+  lsan_common_fuchsia.cpp
   lsan_common_linux.cpp
   lsan_common_mac.cpp
   )
@@ -12,8 +13,8 @@
 set(LSAN_SOURCES
   lsan.cpp
   lsan_allocator.cpp
-  lsan_linux.cpp
   lsan_interceptors.cpp
+  lsan_linux.cpp
   lsan_mac.cpp
   lsan_malloc_mac.cpp
   lsan_preinit.cpp
diff --git a/compiler-rt/lib/lsan/lsan.cpp b/compiler-rt/lib/lsan/lsan.cpp
--- a/compiler-rt/lib/lsan/lsan.cpp
+++ b/compiler-rt/lib/lsan/lsan.cpp
@@ -87,6 +87,7 @@
   __sanitizer_set_report_path(common_flags()->log_path);
 }
 
+#if !SANITIZER_FUCHSIA
 static void OnStackUnwind(const SignalContext &sig, const void *,
                           BufferedStackTrace *stack) {
   stack->Unwind(StackTrace::GetNextInstructionPc(sig.pc), sig.bp, sig.context,
@@ -97,6 +98,7 @@
   HandleDeadlySignal(siginfo, context, GetCurrentThread(), &OnStackUnwind,
                      nullptr);
 }
+#endif
 
 extern "C" void __lsan_init() {
   CHECK(!lsan_init_is_running);
@@ -113,7 +115,9 @@
   InitTlsSize();
   InitializeInterceptors();
   InitializeThreadRegistry();
+#if !SANITIZER_FUCHSIA
   InstallDeadlySignalHandlers(LsanOnDeadlySignal);
+#endif
   u32 tid = ThreadCreate(0, 0, true);
   CHECK_EQ(tid, 0);
   ThreadStart(tid, GetTid());
diff --git a/compiler-rt/lib/lsan/lsan_allocator.h b/compiler-rt/lib/lsan/lsan_allocator.h
--- a/compiler-rt/lib/lsan/lsan_allocator.h
+++ b/compiler-rt/lib/lsan/lsan_allocator.h
@@ -66,7 +66,10 @@
 using PrimaryAllocatorASVT = SizeClassAllocator32<AP32<AddressSpaceView>>;
 using PrimaryAllocator = PrimaryAllocatorASVT<LocalAddressSpaceView>;
 #elif defined(__x86_64__) || defined(__powerpc64__)
-# if defined(__powerpc64__)
+# if SANITIZER_FUCHSIA
+const uptr kAllocatorSpace = ~(uptr)0;
+const uptr kAllocatorSize  =  0x40000000000ULL;  // 4T.
+# elif defined(__powerpc64__)
 const uptr kAllocatorSpace = 0xa0000000000ULL;
 const uptr kAllocatorSize  = 0x20000000000ULL;  // 2T.
 # else
diff --git a/compiler-rt/lib/lsan/lsan_common.h b/compiler-rt/lib/lsan/lsan_common.h
--- a/compiler-rt/lib/lsan/lsan_common.h
+++ b/compiler-rt/lib/lsan/lsan_common.h
@@ -40,7 +40,7 @@
 #elif defined(__arm__) && \
     SANITIZER_LINUX && !SANITIZER_ANDROID
 #define CAN_SANITIZE_LEAKS 1
-#elif SANITIZER_NETBSD
+#elif SANITIZER_NETBSD || SANITIZER_FUCHSIA
 #define CAN_SANITIZE_LEAKS 1
 #else
 #define CAN_SANITIZE_LEAKS 0
@@ -126,12 +126,20 @@
   uptr size;
 };
 
+struct CheckForLeaksParam {
+  Frontier frontier;
+  LeakReport leak_report;
+  bool success = false;
+};
+
 InternalMmapVector<RootRegion> const *GetRootRegions();
 void ScanRootRegion(Frontier *frontier, RootRegion const &region,
                     uptr region_begin, uptr region_end, bool is_readable);
+void ForEachExtraStackRangeCb(uptr begin, uptr end, void* arg);
 // Run stoptheworld while holding any platform-specific locks, as well as the
 // allocator and thread registry locks.
-void LockStuffAndStopTheWorld(StopTheWorldCallback callback, void* argument);
+void LockStuffAndStopTheWorld(StopTheWorldCallback callback,
+                              CheckForLeaksParam* argument);
 
 void ScanRangeForPointers(uptr begin, uptr end,
                           Frontier *frontier,
diff --git a/compiler-rt/lib/lsan/lsan_common.cpp b/compiler-rt/lib/lsan/lsan_common.cpp
--- a/compiler-rt/lib/lsan/lsan_common.cpp
+++ b/compiler-rt/lib/lsan/lsan_common.cpp
@@ -211,6 +211,13 @@
   ScanRangeForPointers(begin, end, frontier, "FAKE STACK", kReachable);
 }
 
+#if SANITIZER_FUCHSIA
+
+// Fuchsia handles all threads together with its own callback.
+static void ProcessThreads(SuspendedThreadsList const &, Frontier *) {}
+
+#else
+
 // Scans thread data (stacks and TLS) for heap pointers.
 static void ProcessThreads(SuspendedThreadsList const &suspended_threads,
                            Frontier *frontier) {
@@ -308,6 +315,8 @@
   }
 }
 
+#endif  // SANITIZER_FUCHSIA
+
 void ScanRootRegion(Frontier *frontier, const RootRegion &root_region,
                     uptr region_begin, uptr region_end, bool is_readable) {
   uptr intersection_begin = Max(root_region.begin, region_begin);
@@ -443,25 +452,23 @@
 }
 
 // Sets the appropriate tag on each chunk.
-static void ClassifyAllChunks(SuspendedThreadsList const &suspended_threads) {
-  // Holds the flood fill frontier.
-  Frontier frontier;
-
-  ForEachChunk(CollectIgnoredCb, &frontier);
-  ProcessGlobalRegions(&frontier);
-  ProcessThreads(suspended_threads, &frontier);
-  ProcessRootRegions(&frontier);
-  FloodFillTag(&frontier, kReachable);
+static void ClassifyAllChunks(SuspendedThreadsList const &suspended_threads,
+                              Frontier *frontier) {
+  ForEachChunk(CollectIgnoredCb, frontier);
+  ProcessGlobalRegions(frontier);
+  ProcessThreads(suspended_threads, frontier);
+  ProcessRootRegions(frontier);
+  FloodFillTag(frontier, kReachable);
 
-  CHECK_EQ(0, frontier.size());
-  ProcessPC(&frontier);
+  CHECK_EQ(0, frontier->size());
+  ProcessPC(frontier);
 
   // The check here is relatively expensive, so we do this in a separate flood
   // fill. That way we can skip the check for chunks that are reachable
   // otherwise.
   LOG_POINTERS("Processing platform-specific allocations.\n");
-  ProcessPlatformSpecificAllocations(&frontier);
-  FloodFillTag(&frontier, kReachable);
+  ProcessPlatformSpecificAllocations(frontier);
+  FloodFillTag(frontier, kReachable);
 
   // Iterate over leaked chunks and mark those that are reachable from other
   // leaked chunks.
@@ -521,10 +528,13 @@
   Printf("%s\n\n", line);
 }
 
-struct CheckForLeaksParam {
-  bool success;
-  LeakReport leak_report;
-};
+#if SANITIZER_FUCHSIA
+
+// Fuchsia provides a libc interface that guarantees all threads are
+// covered, and SuspendedThreadList is never really used.
+static void ReportUnsuspendedThreads(const SuspendedThreadsList &) {}
+
+#else
 
 static void ReportIfNotSuspended(ThreadContextBase *tctx, void *arg) {
   const InternalMmapVector<tid_t> &suspended_threads =
@@ -550,13 +560,15 @@
       &ReportIfNotSuspended, &threads);
 }
 
+#endif  // SANITIZER_FUCHSIA
+
 static void CheckForLeaksCallback(const SuspendedThreadsList &suspended_threads,
                                   void *arg) {
   CheckForLeaksParam *param = reinterpret_cast<CheckForLeaksParam *>(arg);
   CHECK(param);
   CHECK(!param->success);
   ReportUnsuspendedThreads(suspended_threads);
-  ClassifyAllChunks(suspended_threads);
+  ClassifyAllChunks(suspended_threads, &param->frontier);
   ForEachChunk(CollectLeaksCb, &param->leak_report);
   // Clean up for subsequent leak checks. This assumes we did not overwrite any
   // kIgnored tags.
@@ -569,7 +581,6 @@
       return false;
   EnsureMainThreadIDIsCorrect();
   CheckForLeaksParam param;
-  param.success = false;
   LockStuffAndStopTheWorld(CheckForLeaksCallback, &param);
 
   if (!param.success) {
diff --git a/compiler-rt/lib/lsan/lsan_common_fuchsia.cpp b/compiler-rt/lib/lsan/lsan_common_fuchsia.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/lib/lsan/lsan_common_fuchsia.cpp
@@ -0,0 +1,141 @@
+//=-- lsan_common_fuchsia.cpp --------------------------------------------===//
+//
+// 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 LeakSanitizer.
+// Implementation of common leak checking functionality. Fuchsia-specific code.
+//
+//===---------------------------------------------------------------------===//
+
+#include "lsan_common.h"
+#include "sanitizer_common/sanitizer_platform.h"
+
+#if CAN_SANITIZE_LEAKS && SANITIZER_FUCHSIA
+#include <zircon/sanitizer.h>
+
+#include "sanitizer_common/sanitizer_flags.h"
+#include "sanitizer_common/sanitizer_thread_registry.h"
+
+// Ensure that the Zircon system ABI is linked in.
+#pragma comment(lib, "zircon")
+
+namespace __lsan {
+
+void InitializePlatformSpecificModules() {}
+
+LoadedModule *GetLinker() { return nullptr; }
+
+__attribute__((tls_model("initial-exec"))) THREADLOCAL int disable_counter;
+bool DisabledInThisThread() { return disable_counter > 0; }
+void DisableInThisThread() { disable_counter++; }
+void EnableInThisThread() {
+  if (disable_counter == 0) {
+    DisableCounterUnderflow();
+  }
+  disable_counter--;
+}
+
+// There is nothing left to do after the globals callbacks.
+void ProcessGlobalRegions(Frontier *frontier) {}
+
+// Nothing to do here.
+void ProcessPlatformSpecificAllocations(Frontier *frontier) {}
+
+// On Fuchsia, we can intercept _Exit gracefully, and return a failing exit
+// code if required at that point.  Calling Die() here is undefined
+// behavior and causes rare race conditions.
+void HandleLeaks() {}
+
+int ExitHook(int status) {
+  return status == 0 && HasReportedLeaks() ? common_flags()->exitcode : status;
+}
+
+void LockStuffAndStopTheWorld(StopTheWorldCallback callback,
+                              CheckForLeaksParam *argument) {
+  LockThreadRegistry();
+  LockAllocator();
+
+  struct Params {
+    StopTheWorldCallback callback;
+    CheckForLeaksParam *argument;
+  } params = {callback, argument};
+
+  // Callback from libc for globals (data/bss modulo relro), when enabled.
+  auto globals = +[](void *chunk, size_t size, void *data) {
+    auto params = static_cast<const Params *>(data);
+    uptr begin = reinterpret_cast<uptr>(chunk);
+    uptr end = begin + size;
+    ScanGlobalRange(begin, end, &params->argument->frontier);
+  };
+
+  // Callback from libc for thread stacks.
+  auto stacks = +[](void *chunk, size_t size, void *data) {
+    auto params = static_cast<const Params *>(data);
+    uptr begin = reinterpret_cast<uptr>(chunk);
+    uptr end = begin + size;
+    ScanRangeForPointers(begin, end, &params->argument->frontier, "STACK",
+                         kReachable);
+  };
+
+  // Callback from libc for thread registers.
+  auto registers = +[](void *chunk, size_t size, void *data) {
+    auto params = static_cast<const Params *>(data);
+    uptr begin = reinterpret_cast<uptr>(chunk);
+    uptr end = begin + size;
+    ScanRangeForPointers(begin, end, &params->argument->frontier, "REGISTERS",
+                         kReachable);
+  };
+
+  // Callback from libc for TLS regions.  This includes thread_local
+  // variables as well as C11 tss_set and POSIX pthread_setspecific.
+  auto tls = +[](void *chunk, size_t size, void *data) {
+    auto params = static_cast<const Params *>(data);
+    uptr begin = reinterpret_cast<uptr>(chunk);
+    uptr end = begin + size;
+    ScanRangeForPointers(begin, end, &params->argument->frontier, "TLS",
+                         kReachable);
+  };
+
+  // This stops the world and then makes callbacks for various memory regions.
+  // The final callback is the last thing before the world starts up again.
+  __sanitizer_memory_snapshot(
+      flags()->use_globals ? globals : nullptr,
+      flags()->use_stacks ? stacks : nullptr,
+      flags()->use_registers ? registers : nullptr,
+      flags()->use_tls ? tls : nullptr,
+      [](zx_status_t, void *data) {
+        auto params = static_cast<const Params *>(data);
+
+        // We don't use the thread registry at all for enumerating the
+        // threads and their stacks, registers, and TLS regions.  So use it
+        // separately just to call ForEachExtraStackRange, which ASan needs.
+        if (flags()->use_stacks) {
+          GetThreadRegistryLocked()->RunCallbackForEachThreadLocked(
+              [](ThreadContextBase *tctx, void *arg) {
+                ForEachExtraStackRange(tctx->os_id, ForEachExtraStackRangeCb,
+                                       arg);
+              },
+              &params->argument->frontier);
+        }
+
+        params->callback({}, params->argument);
+      },
+      &params);
+
+  UnlockAllocator();
+  UnlockThreadRegistry();
+}
+
+}  // namespace __lsan
+
+// This is declared (in extern "C") by <zircon/sanitizer.h>.
+// _Exit calls this directly to intercept and change the status value.
+int __sanitizer_process_exit_hook(int status) {
+  return __lsan::ExitHook(status);
+}
+
+#endif
diff --git a/compiler-rt/lib/lsan/lsan_common_linux.cpp b/compiler-rt/lib/lsan/lsan_common_linux.cpp
--- a/compiler-rt/lib/lsan/lsan_common_linux.cpp
+++ b/compiler-rt/lib/lsan/lsan_common_linux.cpp
@@ -134,7 +134,8 @@
 // while holding the libdl lock in the parent thread, we can safely reenter it
 // in the tracer. The solution is to run stoptheworld from a dl_iterate_phdr()
 // callback in the parent thread.
-void LockStuffAndStopTheWorld(StopTheWorldCallback callback, void *argument) {
+void LockStuffAndStopTheWorld(StopTheWorldCallback callback,
+                              CheckForLeaksParam *argument) {
   DoStopTheWorldParam param = {callback, argument};
   dl_iterate_phdr(LockStuffAndStopTheWorldCallback, &param);
 }
diff --git a/compiler-rt/lib/lsan/lsan_common_mac.cpp b/compiler-rt/lib/lsan/lsan_common_mac.cpp
--- a/compiler-rt/lib/lsan/lsan_common_mac.cpp
+++ b/compiler-rt/lib/lsan/lsan_common_mac.cpp
@@ -193,7 +193,8 @@
 // causes rare race conditions.
 void HandleLeaks() {}
 
-void LockStuffAndStopTheWorld(StopTheWorldCallback callback, void *argument) {
+void LockStuffAndStopTheWorld(StopTheWorldCallback callback,
+                              CheckForLeaksParam *argument) {
   LockThreadRegistry();
   LockAllocator();
   StopTheWorld(callback, argument);
diff --git a/compiler-rt/lib/lsan/lsan_interceptors.cpp b/compiler-rt/lib/lsan/lsan_interceptors.cpp
--- a/compiler-rt/lib/lsan/lsan_interceptors.cpp
+++ b/compiler-rt/lib/lsan/lsan_interceptors.cpp
@@ -22,7 +22,9 @@
 #include "sanitizer_common/sanitizer_platform_interceptors.h"
 #include "sanitizer_common/sanitizer_platform_limits_netbsd.h"
 #include "sanitizer_common/sanitizer_platform_limits_posix.h"
+#if SANITIZER_POSIX
 #include "sanitizer_common/sanitizer_posix.h"
+#endif
 #include "sanitizer_common/sanitizer_tls_get_addr.h"
 #include "lsan.h"
 #include "lsan_allocator.h"
@@ -61,6 +63,7 @@
 }
 
 INTERCEPTOR(void*, calloc, uptr nmemb, uptr size) {
+#if !SANITIZER_FUCHSIA
   if (lsan_init_is_running) {
     // Hack: dlsym calls calloc before REAL(calloc) is retrieved from dlsym.
     const uptr kCallocPoolSize = 1024;
@@ -72,6 +75,7 @@
     CHECK(allocated < kCallocPoolSize);
     return mem;
   }
+#endif  // !SANITIZER_FUCHSIA
   ENSURE_LSAN_INITED;
   GET_STACK_TRACE_MALLOC;
   return lsan_calloc(nmemb, size, stack);
@@ -100,7 +104,7 @@
   GET_STACK_TRACE_MALLOC;
   return lsan_valloc(size, stack);
 }
-#endif
+#endif  // !SANITIZER_MAC
 
 #if SANITIZER_INTERCEPT_MEMALIGN
 INTERCEPTOR(void*, memalign, uptr alignment, uptr size) {
@@ -307,7 +311,7 @@
 
 ///// Thread initialization and finalization. /////
 
-#if !SANITIZER_NETBSD && !SANITIZER_FREEBSD
+#if !SANITIZER_NETBSD && !SANITIZER_FREEBSD && !SANITIZER_FUCHSIA
 static unsigned g_thread_finalize_key;
 
 static void thread_finalize(void *v) {
@@ -394,6 +398,54 @@
 #define LSAN_MAYBE_INTERCEPT_STRERROR
 #endif
 
+#if SANITIZER_FUCHSIA
+
+// These are declared (in extern "C") by <zircon/sanitizer.h>.
+// The system runtime will call our definitions directly.
+
+// This is called before each thread creation is attempted.  So, in
+// its first call, the calling thread is the initial and sole thread.
+void *__sanitizer_before_thread_create_hook(thrd_t thread, bool detached,
+                                            const char *name, void *stack_base,
+                                            size_t stack_size) {
+  uptr user_id = reinterpret_cast<uptr>(thread);
+  ENSURE_LSAN_INITED;
+  EnsureMainThreadIDIsCorrect();
+  ThreadContext::OnCreatedArgs args;
+  args.stack_begin = reinterpret_cast<uptr>(stack_base);
+  args.stack_end = args.stack_begin + stack_size;
+  u32 tid = ThreadCreate(GetCurrentThread(), user_id, detached, &args);
+  return reinterpret_cast<void *>(static_cast<uptr>(tid));
+}
+
+// This is called after creating a new thread (in the creating thread),
+// with the pointer returned by __sanitizer_before_thread_create_hook (above).
+void __sanitizer_thread_create_hook(void *hook, thrd_t thread, int error) {
+  u32 tid = static_cast<u32>(reinterpret_cast<uptr>(hook));
+  // On success, there is nothing to do here.
+  if (error != thrd_success) {
+    // Clean up the thread registry for the thread creation that didn't happen.
+    ThreadCreateAborted(tid);
+  }
+}
+
+// This is called in the newly-created thread before it runs anything else,
+// with the pointer returned by __sanitizer_before_thread_create_hook (above).
+void __sanitizer_thread_start_hook(void *hook, thrd_t self) {
+  u32 tid = static_cast<u32>(reinterpret_cast<uptr>(hook));
+  SetCurrentThread(tid);
+  ThreadStart(tid, GetTid());
+}
+
+// Each thread runs this just before it exits,
+// with the pointer returned by BeforeThreadCreateHook (above).
+// All per-thread destructors have already been called.
+void __sanitizer_thread_exit_hook(void *hook, thrd_t self) {
+  ThreadFinish();
+}
+
+#else  // !SANITIZER_FUCHSIA
+
 struct ThreadParam {
   void *(*callback)(void *arg);
   void *param;
@@ -477,9 +529,12 @@
 #define COMMON_INTERCEPT_FUNCTION(name) INTERCEPT_FUNCTION(name)
 #include "sanitizer_common/sanitizer_signal_interceptors.inc"
 
+#endif  // !SANITIZER_FUCHSIA
+
 namespace __lsan {
 
 void InitializeInterceptors() {
+#if !SANITIZER_FUCHSIA
   InitializeSignalInterceptors();
 
   INTERCEPT_FUNCTION(malloc);
@@ -515,6 +570,8 @@
     Die();
   }
 #endif
+
+#endif  // !SANITIZER_FUCHSIA
 }
 
 } // namespace __lsan
diff --git a/compiler-rt/lib/lsan/lsan_linux.cpp b/compiler-rt/lib/lsan/lsan_linux.cpp
--- a/compiler-rt/lib/lsan/lsan_linux.cpp
+++ b/compiler-rt/lib/lsan/lsan_linux.cpp
@@ -6,13 +6,13 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file is a part of LeakSanitizer. Linux/NetBSD-specific code.
+// This file is a part of LeakSanitizer. Linux/NetBSD/Fuchsia-specific code.
 //
 //===----------------------------------------------------------------------===//
 
 #include "sanitizer_common/sanitizer_platform.h"
 
-#if SANITIZER_LINUX || SANITIZER_NETBSD
+#if SANITIZER_LINUX || SANITIZER_NETBSD || SANITIZER_FUCHSIA
 
 #include "lsan_allocator.h"
 
@@ -29,4 +29,4 @@
 
 } // namespace __lsan
 
-#endif  // SANITIZER_LINUX || SANITIZER_NETBSD
+#endif  // SANITIZER_LINUX || SANITIZER_NETBSD || SANITIZER_FUCHSIA
diff --git a/compiler-rt/lib/lsan/lsan_thread.h b/compiler-rt/lib/lsan/lsan_thread.h
--- a/compiler-rt/lib/lsan/lsan_thread.h
+++ b/compiler-rt/lib/lsan/lsan_thread.h
@@ -25,6 +25,7 @@
 class ThreadContext : public ThreadContextBase {
  public:
   explicit ThreadContext(int tid);
+  void OnCreated(void *arg) override;
   void OnStarted(void *arg) override;
   void OnFinished() override;
   uptr stack_begin() { return stack_begin_; }
@@ -35,6 +36,10 @@
   uptr cache_end() { return cache_end_; }
   DTLS *dtls() { return dtls_; }
 
+  struct OnCreatedArgs {
+    uptr stack_begin, stack_end;
+  };
+
  private:
   uptr stack_begin_, stack_end_,
        cache_begin_, cache_end_,
@@ -47,7 +52,8 @@
 void ThreadStart(u32 tid, tid_t os_id,
                  ThreadType thread_type = ThreadType::Regular);
 void ThreadFinish();
-u32 ThreadCreate(u32 tid, uptr uid, bool detached);
+u32 ThreadCreate(u32 tid, uptr uid, bool detached, void *arg = nullptr);
+void ThreadCreateAborted(u32 tid);
 void ThreadJoin(u32 tid);
 u32 ThreadTid(uptr uid);
 
diff --git a/compiler-rt/lib/lsan/lsan_thread.cpp b/compiler-rt/lib/lsan/lsan_thread.cpp
--- a/compiler-rt/lib/lsan/lsan_thread.cpp
+++ b/compiler-rt/lib/lsan/lsan_thread.cpp
@@ -55,12 +55,34 @@
   DTLS *dtls;
 };
 
+// On Fuchsia, the stack bounds of a new thread are available before
+// the thread itself has started running.
+void ThreadContext::OnCreated(void *arg) {
+  auto args = reinterpret_cast<OnCreatedArgs *>(arg);
+#if SANITIZER_FUCHSIA
+  if (args) {
+    // Stack bounds passed through from __sanitizer_before_thread_create_hook.
+    stack_begin_ = args->stack_begin;
+    stack_end_ = args->stack_end;
+  } else {
+    // This is the initial thread.
+    __sanitizer::GetThreadStackTopAndBottom(true, &stack_end_, &stack_begin_);
+  }
+#else
+  CHECK_EQ(args, nullptr);
+#endif
+}
+
 void ThreadContext::OnStarted(void *arg) {
   OnStartedArgs *args = reinterpret_cast<OnStartedArgs *>(arg);
+#if !SANITIZER_FUCHSIA
+  // These are set in OnCreated, above.
   stack_begin_ = args->stack_begin;
   stack_end_ = args->stack_end;
+  // These are never used on Fuchsia.
   tls_begin_ = args->tls_begin;
   tls_end_ = args->tls_end;
+#endif
   cache_begin_ = args->cache_begin;
   cache_end_ = args->cache_end;
   dtls_ = args->dtls;
@@ -71,19 +93,20 @@
   DTLS_Destroy();
 }
 
-u32 ThreadCreate(u32 parent_tid, uptr user_id, bool detached) {
-  return thread_registry->CreateThread(user_id, detached, parent_tid,
-                                       /* arg */ nullptr);
+u32 ThreadCreate(u32 parent_tid, uptr user_id, bool detached, void *arg) {
+  return thread_registry->CreateThread(user_id, detached, parent_tid, arg);
 }
 
 void ThreadStart(u32 tid, tid_t os_id, ThreadType thread_type) {
   OnStartedArgs args;
+#if !SANITIZER_FUCHSIA
   uptr stack_size = 0;
   uptr tls_size = 0;
   GetThreadStackAndTls(tid == 0, &args.stack_begin, &stack_size,
                        &args.tls_begin, &tls_size);
   args.stack_end = args.stack_begin + stack_size;
   args.tls_end = args.tls_begin + tls_size;
+#endif
   GetAllocatorCacheRange(&args.cache_begin, &args.cache_end);
   args.dtls = DTLS_Get();
   thread_registry->StartThread(tid, os_id, thread_type, &args);
@@ -94,6 +117,10 @@
   SetCurrentThread(kInvalidTid);
 }
 
+void ThreadCreateAborted(u32 tid) {
+  thread_registry->FinishThread(tid);
+}
+
 ThreadContext *CurrentThreadContext() {
   if (!thread_registry) return nullptr;
   if (GetCurrentThread() == kInvalidTid)
diff --git a/compiler-rt/lib/sanitizer_common/CMakeLists.txt b/compiler-rt/lib/sanitizer_common/CMakeLists.txt
--- a/compiler-rt/lib/sanitizer_common/CMakeLists.txt
+++ b/compiler-rt/lib/sanitizer_common/CMakeLists.txt
@@ -35,6 +35,7 @@
   sanitizer_procmaps_solaris.cpp
   sanitizer_rtems.cpp
   sanitizer_solaris.cpp
+  sanitizer_stoptheworld_fuchsia.cpp
   sanitizer_stoptheworld_mac.cpp
   sanitizer_suppressions.cpp
   sanitizer_tls_get_addr.cpp
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_stoptheworld_fuchsia.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_stoptheworld_fuchsia.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_stoptheworld_fuchsia.cpp
@@ -0,0 +1,42 @@
+//===-- sanitizer_stoptheworld_fuchsia.cpp -------------------------------===//
+//
+// 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
+//
+//===---------------------------------------------------------------------===//
+//
+// See sanitizer_stoptheworld.h for details.
+//
+//===---------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+
+#if SANITIZER_FUCHSIA
+
+#include <zircon/sanitizer.h>
+
+#include "sanitizer_stoptheworld.h"
+
+namespace __sanitizer {
+
+// The Fuchsia implementation stops the world but doesn't offer a real
+// SuspendedThreadsList argument.  This is enough for ASan's use case,
+// and LSan does not use this API on Fuchsia.
+void StopTheWorld(StopTheWorldCallback callback, void *argument) {
+  struct Params {
+    StopTheWorldCallback callback;
+    void *argument;
+  } params = {callback, argument};
+  __sanitizer_memory_snapshot(
+      nullptr, nullptr, nullptr, nullptr,
+      [](zx_status_t, void *data) {
+        auto params = reinterpret_cast<Params *>(data);
+        params->callback({}, params->argument);
+      },
+      &params);
+}
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_FUCHSIA