Index: lib/asan/asan_allocator.h
===================================================================
--- lib/asan/asan_allocator.h
+++ lib/asan/asan_allocator.h
@@ -119,7 +119,11 @@
 };
 
 #if SANITIZER_CAN_USE_ALLOCATOR64
-# if defined(__powerpc64__)
+# if SANITIZER_FUCHSIA
+const uptr kAllocatorSpace = ~(uptr)0;
+const uptr kAllocatorSize  =  0x40000000000ULL;  // 4T.
+typedef DefaultSizeClassMap SizeClassMap;
+# elif defined(__powerpc64__)
 const uptr kAllocatorSpace =  0xa0000000000ULL;
 const uptr kAllocatorSize  =  0x20000000000ULL;  // 2T.
 typedef DefaultSizeClassMap SizeClassMap;
Index: lib/asan/asan_malloc_linux.cc
===================================================================
--- lib/asan/asan_malloc_linux.cc
+++ lib/asan/asan_malloc_linux.cc
@@ -15,7 +15,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "sanitizer_common/sanitizer_platform.h"
-#if SANITIZER_FREEBSD || SANITIZER_LINUX
+#if SANITIZER_FREEBSD || SANITIZER_FUCHSIA || SANITIZER_LINUX
 
 #include "sanitizer_common/sanitizer_tls_get_addr.h"
 #include "asan_allocator.h"
@@ -26,6 +26,8 @@
 // ---------------------- Replacement functions ---------------- {{{1
 using namespace __asan;  // NOLINT
 
+#if !SANITIZER_FUCHSIA
+
 static uptr allocated_for_dlsym;
 static const uptr kDlsymAllocPoolSize = 1024;
 static uptr alloc_memory_for_dlsym[kDlsymAllocPoolSize];
@@ -43,6 +45,47 @@
   return mem;
 }
 
+static bool MaybeInDlsym() {
+  return UNLIKELY(asan_init_is_running);
+}
+
+static void *ReallocFromLocalPool(void *ptr, uptr size) {
+  const uptr offset = (uptr)ptr - (uptr)alloc_memory_for_dlsym;
+  const uptr copy_size = Min(size, kDlsymAllocPoolSize - offset);
+  void *new_ptr;
+  if (UNLIKELY(MaybeInDlsym())) {
+    new_ptr = AllocateFromLocalPool(size);
+  } else {
+    ENSURE_ASAN_INITED();
+    GET_STACK_TRACE_MALLOC;
+    new_ptr = asan_malloc(size, &stack);
+  }
+  internal_memcpy(new_ptr, ptr, copy_size);
+  return new_ptr;
+}
+
+#else // SANITIZER_FUCHSIA
+
+// Fuchsia doesn't use dlsym-based interceptors.
+
+static bool IsInDlsymAllocPool(const void *) {
+  return false;
+}
+
+static bool MaybeInDlsym() {
+  return false;
+}
+
+// These will never be called.
+static void *AllocateFromLocalPool(uptr) {
+  __builtin_trap();
+}
+static void *ReallocFromLocalPool(void *, uptr) {
+  __builtin_trap();
+}
+
+#endif // !SANITIZER_FUCHSIA
+
 INTERCEPTOR(void, free, void *ptr) {
   GET_STACK_TRACE_FREE;
   if (UNLIKELY(IsInDlsymAllocPool(ptr)))
@@ -60,7 +103,7 @@
 #endif // SANITIZER_INTERCEPT_CFREE
 
 INTERCEPTOR(void*, malloc, uptr size) {
-  if (UNLIKELY(asan_init_is_running))
+  if (UNLIKELY(MaybeInDlsym()))
     // Hack: dlsym calls malloc before REAL(malloc) is retrieved from dlsym.
     return AllocateFromLocalPool(size);
   ENSURE_ASAN_INITED();
@@ -69,7 +112,7 @@
 }
 
 INTERCEPTOR(void*, calloc, uptr nmemb, uptr size) {
-  if (UNLIKELY(asan_init_is_running))
+  if (UNLIKELY(MaybeInDlsym()))
     // Hack: dlsym calls calloc before REAL(calloc) is retrieved from dlsym.
     return AllocateFromLocalPool(nmemb * size);
   ENSURE_ASAN_INITED();
@@ -78,21 +121,9 @@
 }
 
 INTERCEPTOR(void*, realloc, void *ptr, uptr size) {
-  if (UNLIKELY(IsInDlsymAllocPool(ptr))) {
-    const uptr offset = (uptr)ptr - (uptr)alloc_memory_for_dlsym;
-    const uptr copy_size = Min(size, kDlsymAllocPoolSize - offset);
-    void *new_ptr;
-    if (UNLIKELY(asan_init_is_running)) {
-      new_ptr = AllocateFromLocalPool(size);
-    } else {
-      ENSURE_ASAN_INITED();
-      GET_STACK_TRACE_MALLOC;
-      new_ptr = asan_malloc(size, &stack);
-    }
-    internal_memcpy(new_ptr, ptr, copy_size);
-    return new_ptr;
-  }
-  if (UNLIKELY(asan_init_is_running))
+  if (UNLIKELY(IsInDlsymAllocPool(ptr)))
+    return ReallocFromLocalPool(ptr, size);
+  if (UNLIKELY(MaybeInDlsym()))
     return AllocateFromLocalPool(size);
   ENSURE_ASAN_INITED();
   GET_STACK_TRACE_MALLOC;
@@ -226,4 +257,4 @@
 }  // namespace __asan
 #endif  // SANITIZER_ANDROID
 
-#endif  // SANITIZER_FREEBSD || SANITIZER_LINUX
+#endif  // SANITIZER_FREEBSD || SANITIZER_FUCHSIA || SANITIZER_LINUX
Index: lib/sanitizer_common/sanitizer_platform.h
===================================================================
--- lib/sanitizer_common/sanitizer_platform.h
+++ lib/sanitizer_common/sanitizer_platform.h
@@ -187,7 +187,7 @@
 // For such platforms build this code with -DSANITIZER_CAN_USE_ALLOCATOR64=0 or
 // change the definition of SANITIZER_CAN_USE_ALLOCATOR64 here.
 #ifndef SANITIZER_CAN_USE_ALLOCATOR64
-# if SANITIZER_ANDROID && defined(__aarch64__)
+# if (SANITIZER_ANDROID && defined(__aarch64__)) || SANITIZER_FUCHSIA
 #  define SANITIZER_CAN_USE_ALLOCATOR64 1
 # elif defined(__mips64) || defined(__aarch64__)
 #  define SANITIZER_CAN_USE_ALLOCATOR64 0