Index: lib/asan/asan_interface_internal.h
===================================================================
--- lib/asan/asan_interface_internal.h
+++ lib/asan/asan_interface_internal.h
@@ -223,6 +223,11 @@
   void __asan_alloca_poison(uptr addr, uptr size);
   SANITIZER_INTERFACE_ATTRIBUTE
   void __asan_allocas_unpoison(uptr top, uptr bottom);
+
+  SANITIZER_INTERFACE_ATTRIBUTE
+  void __asan_enter_fiber(const void* top, const void* bottom);
+  SANITIZER_INTERFACE_ATTRIBUTE
+  void __asan_exit_fiber();
 }  // extern "C"
 
 #endif  // ASAN_INTERFACE_INTERNAL_H
Index: lib/asan/asan_thread.h
===================================================================
--- lib/asan/asan_thread.h
+++ lib/asan/asan_thread.h
@@ -66,9 +66,13 @@
   thread_return_t ThreadStart(uptr os_id,
                               atomic_uintptr_t *signal_thread_is_registered);
 
-  uptr stack_top() { return stack_top_; }
-  uptr stack_bottom() { return stack_bottom_; }
-  uptr stack_size() { return stack_size_; }
+  uptr stack_top() { return fiber_stack_top_ ? fiber_stack_top_ : stack_top_; }
+  uptr stack_bottom() {
+    return fiber_stack_bottom_ ? fiber_stack_bottom_ : stack_bottom_;
+  }
+  uptr stack_size() {
+    return fiber_stack_size_ ? fiber_stack_size_ : stack_size_;
+  }
   uptr tls_begin() { return tls_begin_; }
   uptr tls_end() { return tls_end_; }
   DTLS *dtls() { return dtls_; }
@@ -95,6 +99,20 @@
     t->Destroy(tid);
   }
 
+  void EnterFiber(uptr top, uptr bottom) {
+    if (bottom > top)
+      Report("WARNING: __asan_enter_fiber called with inverted stack\n");
+    if (fiber_stack_top_ || fiber_stack_bottom_ || fiber_stack_size_)
+      Report("WARNING: __asan_enter_fiber called twice\n");
+    fiber_stack_top_ = top;
+    fiber_stack_bottom_ = bottom;
+    fiber_stack_size_ = fiber_stack_top_ - fiber_stack_bottom_;
+  }
+
+  void ExitFiber() {
+    fiber_stack_top_ = fiber_stack_bottom_ = fiber_stack_size_ = 0;
+  }
+
   bool has_fake_stack() {
     return (reinterpret_cast<uptr>(fake_stack_) > 1);
   }
@@ -135,6 +153,11 @@
   // stack_size_ == stack_top_ - stack_bottom_;
   // It needs to be set in a async-signal-safe manner.
   uptr stack_size_;
+
+  uptr fiber_stack_top_;
+  uptr fiber_stack_bottom_;
+  uptr fiber_stack_size_;
+
   uptr tls_begin_;
   uptr tls_end_;
   DTLS *dtls_;
Index: lib/asan/asan_thread.cc
===================================================================
--- lib/asan/asan_thread.cc
+++ lib/asan/asan_thread.cc
@@ -198,6 +198,7 @@
   GetThreadStackAndTls(tid() == 0, &stack_bottom_, &stack_size_, &tls_begin_,
                        &tls_size);
   stack_top_ = stack_bottom_ + stack_size_;
+  fiber_stack_top_ = fiber_stack_bottom_ = fiber_stack_size_ = 0;
   tls_end_ = tls_begin_ + tls_size;
   dtls_ = DTLS_Get();
 
@@ -357,3 +358,25 @@
   __asan::EnsureMainThreadIDIsCorrect();
 }
 } // namespace __lsan
+
+// ---------------------- Interface ---------------- {{{1
+using namespace __asan;  // NOLINT
+
+void NOINLINE __asan_enter_fiber(const void *stack_top,
+                                 const void *stack_bottom) {
+  AsanThread *t = GetCurrentThread();
+  if (!t) {
+    Report("WARNING: __asan_enter_fiber called from unknown thread\n");
+    return;
+  }
+  t->EnterFiber((uptr)stack_top, (uptr)stack_bottom);
+}
+
+void NOINLINE __asan_exit_fiber() {
+  AsanThread *t = GetCurrentThread();
+  if (!t) {
+    Report("WARNING: __asan_exit_fiber called from unknown thread\n");
+    return;
+  }
+  t->ExitFiber();
+}