diff --git a/ChangeLog.md b/ChangeLog.md
index 512f7422e2ee7..3dc0fe52e465d 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -17,6 +17,8 @@ See docs/process.md for how version tagging works.
 
 Current Trunk
 -------------
+- ASAN_SHADOW_SIZE is deprecated. When using AddressSanitizer, the correct
+  amount of shadow memory will now be calculated automatically.
 
 2.0.5: 09/28/2020
 -----------------
diff --git a/emcc.py b/emcc.py
index 4b31668062fcb..c7e8a58344b00 100755
--- a/emcc.py
+++ b/emcc.py
@@ -1498,12 +1498,6 @@ def filter_out_duplicate_dynamic_libs(inputs):
       # so setErrNo JS library function can report errno back to C
       shared.Settings.EXPORTED_FUNCTIONS += ['___errno_location']
 
-    if shared.Settings.GLOBAL_BASE < 0:
-      # default if nothing else sets it
-      # a higher global base is useful for optimizing load/store offsets, as it
-      # enables the --post-emscripten pass
-      shared.Settings.GLOBAL_BASE = 1024
-
     if shared.Settings.SAFE_HEAP:
       # SAFE_HEAP check includes calling emscripten_get_sbrk_ptr() from wasm
       shared.Settings.EXPORTED_FUNCTIONS += ['_emscripten_get_sbrk_ptr']
@@ -1777,9 +1771,20 @@ def include_and_export(name):
         '_asan_c_store_f', '_asan_c_store_d',
       ]
 
-      shared.Settings.GLOBAL_BASE = shared.Settings.ASAN_SHADOW_SIZE
-      shared.Settings.INITIAL_MEMORY += shared.Settings.ASAN_SHADOW_SIZE
-      assert shared.Settings.INITIAL_MEMORY < 2**32
+      if shared.Settings.ASAN_SHADOW_SIZE != -1:
+        diagnostics.warning('emcc', 'ASAN_SHADOW_SIZE is ignored and will be removed in a future release')
+
+      if shared.Settings.GLOBAL_BASE != -1:
+        exit_with_error("ASan does not support custom GLOBAL_BASE")
+
+      max_mem = shared.Settings.INITIAL_MEMORY
+      if shared.Settings.ALLOW_MEMORY_GROWTH:
+        max_mem = shared.Settings.MAXIMUM_MEMORY
+        if max_mem == -1:
+          exit_with_error('ASan requires a finite MAXIMUM_MEMORY')
+
+      shadow_size = max_mem // 8
+      shared.Settings.GLOBAL_BASE = shadow_size
 
       if shared.Settings.SAFE_HEAP:
         # SAFE_HEAP instruments ASan's shadow memory accesses.
@@ -1793,6 +1798,12 @@ def include_and_export(name):
     if sanitize and '-g4' in args:
       shared.Settings.LOAD_SOURCE_MAP = 1
 
+    if shared.Settings.GLOBAL_BASE == -1:
+      # default if nothing else sets it
+      # a higher global base is useful for optimizing load/store offsets, as it
+      # enables the --post-emscripten pass
+      shared.Settings.GLOBAL_BASE = 1024
+
     # various settings require malloc/free support from JS
     if shared.Settings.RELOCATABLE or \
        shared.Settings.BUILD_AS_WORKER or \
diff --git a/src/library.js b/src/library.js
index 038c78c03bec6..f40f2fd7c6f45 100644
--- a/src/library.js
+++ b/src/library.js
@@ -551,21 +551,6 @@ LibraryManager.library = {
       return false;
 #endif
     }
-#if USE_ASAN
-    // One byte of ASan's shadow memory shadows 8 bytes of real memory. Shadow memory area has a fixed size,
-    // so do not allow resizing past that limit.
-    maxHeapSize = Math.min(maxHeapSize, {{{ 8 * ASAN_SHADOW_SIZE }}});
-    if (requestedSize > maxHeapSize) {
-#if ASSERTIONS
-      err('Failed to grow the heap from ' + oldSize + ', as we reached the limit of our shadow memory. Increase ASAN_SHADOW_SIZE.');
-#endif
-#if ABORTING_MALLOC
-      abortOnCannotGrowMemory(requestedSize);
-#else
-      return false;
-#endif
-    }
-#endif
 
     var minHeapSize = 16777216;
 
diff --git a/src/settings.js b/src/settings.js
index bf1ba86bd8c2e..2788fd5770aba 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -1530,9 +1530,10 @@ var MINIFY_HTML = 1;
 // bisecting.
 var MAYBE_WASM2JS = 0;
 
-// The size of our shadow memory.
-// By default, we have 32 MiB. This supports 256 MiB of real memory.
-var ASAN_SHADOW_SIZE = 33554432;
+// This option is no longer used. The appropriate shadow memory size is now
+// calculated from INITIAL_MEMORY and MAXIMUM_MEMORY. Will be removed in a
+// future release.
+var ASAN_SHADOW_SIZE = -1
 
 // Internal: Tracks whether Emscripten should link in exception throwing (C++
 // 'throw') support library. This does not need to be set directly, but pass
diff --git a/tests/asan-no-leak.js b/tests/asan-no-leak.js
index 0c5b359faf7d9..e50bde5ca7938 100644
--- a/tests/asan-no-leak.js
+++ b/tests/asan-no-leak.js
@@ -1 +1,5 @@
-Module = {ASAN_OPTIONS: 'detect_leaks=0'};
+if (Module != undefined) {
+  Module.ASAN_OPTIONS = 'detect_leaks=0';
+} else {
+  Module = {ASAN_OPTIONS: 'detect_leaks=0'};
+}
diff --git a/tests/test_core.py b/tests/test_core.py
index e91c8d0ae0aa9..a2a9b78249425 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -5774,7 +5774,10 @@ def test_fakestat(self):
     self.do_run_in_out_file_test('tests', 'core', 'test_fakestat.c')
 
   def test_mmap(self):
-    self.set_setting('INITIAL_MEMORY', 128 * 1024 * 1024)
+    # ASan needs more memory, but that is set up separately
+    if '-fsanitize=address' not in self.emcc_args:
+      self.set_setting('INITIAL_MEMORY', 128 * 1024 * 1024)
+
     # needs to flush stdio streams
     self.set_setting('EXIT_RUNTIME', 1)
     self.do_run_in_out_file_test('tests', 'core', 'test_mmap.c')
@@ -6278,12 +6281,6 @@ def run_all(x):
   @no_asan('autodebug logging interferes with asan')
   @with_env_modify({'EMCC_AUTODEBUG': '1'})
   def test_autodebug_wasm(self):
-    # Autodebug does not work with too much shadow memory.
-    # Memory consumed by autodebug depends on the size of the WASM linear memory.
-    # With a large shadow memory, the JS engine runs out of memory.
-    if '-fsanitize=address' in self.emcc_args:
-      self.set_setting('ASAN_SHADOW_SIZE', 16 * 1024 * 1024)
-
     # test that the program both works and also emits some of the logging
     # (but without the specific output, as it is logging the actual locals
     # used and so forth, which will change between opt modes and updates of
@@ -8015,7 +8012,9 @@ def test_template_class_deduction(self):
     'cpp': ['test_asan_no_error.cpp'],
   })
   def test_asan_no_error(self, name):
-    self.emcc_args += ['-fsanitize=address', '-s', 'ALLOW_MEMORY_GROWTH=1']
+    self.emcc_args.append('-fsanitize=address')
+    self.emcc_args.append('-sALLOW_MEMORY_GROWTH=1')
+    self.emcc_args.append('-sINITIAL_MEMORY=314572800')
     self.do_runf(path_from_root('tests', 'core', name), '', assert_returncode=NON_ZERO)
 
   # note: these tests have things like -fno-builtin-memset in order to avoid
@@ -8082,7 +8081,9 @@ def test_asan(self, name, expected_output, cflags=None):
     if not self.get_setting('WASM'):
       self.skipTest('wasm2js has no ASan support')
 
-    self.emcc_args += ['-fsanitize=address', '-s', 'ALLOW_MEMORY_GROWTH=1']
+    self.emcc_args.append('-fsanitize=address')
+    self.emcc_args.append('-sALLOW_MEMORY_GROWTH=1')
+    self.emcc_args.append('-sINITIAL_MEMORY=314572800')
     if cflags:
       self.emcc_args += cflags
     self.do_runf(path_from_root('tests', 'core', name),
@@ -8091,14 +8092,16 @@ def test_asan(self, name, expected_output, cflags=None):
 
   @no_wasm2js('TODO: ASAN in wasm2js')
   def test_asan_js_stack_op(self):
-    self.emcc_args += ['-fsanitize=address', '-s', 'ALLOW_MEMORY_GROWTH=1']
+    self.emcc_args.append('-fsanitize=address')
+    self.emcc_args.append('-sALLOW_MEMORY_GROWTH=1')
+    self.emcc_args.append('-sINITIAL_MEMORY=314572800')
     self.do_runf(path_from_root('tests', 'core', 'test_asan_js_stack_op.c'),
                  expected_output='Hello, World!')
 
   @no_wasm2js('TODO: ASAN in wasm2js')
   def test_asan_api(self):
     self.emcc_args.append('-fsanitize=address')
-    self.set_setting('ALLOW_MEMORY_GROWTH')
+    self.set_setting('INITIAL_MEMORY', 314572800)
     self.do_run_in_out_file_test('tests', 'core', 'test_asan_api.c')
 
   @no_wasm2js('TODO: ASAN in wasm2js')
@@ -8108,6 +8111,7 @@ def test_asan_modularized_with_closure(self):
     self.emcc_args.append('-sUSE_CLOSURE_COMPILER=1')
     self.emcc_args.append('-fsanitize=address')
     self.emcc_args.append('-sALLOW_MEMORY_GROWTH=1')
+    self.emcc_args.append('-sINITIAL_MEMORY=314572800')
 
     def post(filename):
       with open(filename, 'a') as f:
@@ -8358,10 +8362,10 @@ def setUp(self):
 # Add DEFAULT_TO_CXX=0
 strict = make_run('strict', emcc_args=[], settings={'STRICT': 1})
 
-lsan = make_run('lsan', emcc_args=['-fsanitize=leak'], settings={'ALLOW_MEMORY_GROWTH': 1})
-asan = make_run('asan', emcc_args=['-fsanitize=address'], settings={'ALLOW_MEMORY_GROWTH': 1, 'ASAN_SHADOW_SIZE': 128 * 1024 * 1024})
-asani = make_run('asani', emcc_args=['-fsanitize=address', '--pre-js', os.path.join(os.path.dirname(__file__), 'asan-no-leak.js')],
-                 settings={'ALLOW_MEMORY_GROWTH': 1})
+lsan = make_run('lsan', emcc_args=['-fsanitize=leak', '-O2'], settings={'ALLOW_MEMORY_GROWTH': 1})
+asan = make_run('asan', emcc_args=['-fsanitize=address', '-O2'], settings={'ALLOW_MEMORY_GROWTH': 1, 'INITIAL_MEMORY': 314572800})
+asani = make_run('asani', emcc_args=['-fsanitize=address', '-O2', '--pre-js', os.path.join(os.path.dirname(__file__), 'asan-no-leak.js')],
+                 settings={'ALLOW_MEMORY_GROWTH': 1, 'INITIAL_MEMORY': 314572800})
 
 # Experimental modes (not tested by CI)
 lld = make_run('lld', emcc_args=[], settings={'LLD_REPORT_UNDEFINED': 1})
diff --git a/tests/test_other.py b/tests/test_other.py
index 2ddf31c0a825a..1ae574a60be3e 100644
--- a/tests/test_other.py
+++ b/tests/test_other.py
@@ -8486,21 +8486,21 @@ def test_lsan_no_stack_trace(self):
 
   def test_asan_null_deref(self):
     self.do_smart_test(path_from_root('tests', 'other', 'test_asan_null_deref.c'),
-                       emcc_args=['-fsanitize=address', '-s', 'ALLOW_MEMORY_GROWTH=1'],
+                       emcc_args=['-fsanitize=address', '-sALLOW_MEMORY_GROWTH=1', '-sINITIAL_MEMORY=314572800'],
                        assert_returncode=NON_ZERO, literals=[
       'AddressSanitizer: null-pointer-dereference on address',
     ])
 
   def test_asan_no_stack_trace(self):
     self.do_smart_test(path_from_root('tests', 'other', 'test_lsan_leaks.c'),
-                       emcc_args=['-fsanitize=address', '-s', 'ALLOW_MEMORY_GROWTH=1', '-DDISABLE_CONTEXT', '-s', 'EXIT_RUNTIME'],
+                       emcc_args=['-fsanitize=address', '-sALLOW_MEMORY_GROWTH=1',  '-sINITIAL_MEMORY=314572800', '-DDISABLE_CONTEXT', '-s', 'EXIT_RUNTIME'],
                        assert_returncode=NON_ZERO, literals=[
       'Direct leak of 3427 byte(s) in 3 object(s) allocated from:',
       'SUMMARY: AddressSanitizer: 3427 byte(s) leaked in 3 allocation(s).',
     ])
 
   def test_asan_pthread_stubs(self):
-    self.do_smart_test(path_from_root('tests', 'other', 'test_asan_pthread_stubs.c'), emcc_args=['-fsanitize=address', '-s', 'ALLOW_MEMORY_GROWTH=1'])
+    self.do_smart_test(path_from_root('tests', 'other', 'test_asan_pthread_stubs.c'), emcc_args=['-fsanitize=address', '-sALLOW_MEMORY_GROWTH=1', '-sINITIAL_MEMORY=314572800'])
 
   def test_proxy_to_pthread_stack(self):
     with js_engines_modify([NODE_JS + ['--experimental-wasm-threads', '--experimental-wasm-bulk-memory']]):
@@ -8601,7 +8601,7 @@ def test_mmap_and_munmap_anonymous(self):
     self.do_other_test('mmap_and_munmap_anonymous', emcc_args=['-s', 'NO_FILESYSTEM'])
 
   def test_mmap_and_munmap_anonymous_asan(self):
-    self.do_other_test('mmap_and_munmap_anonymous', emcc_args=['-s', 'NO_FILESYSTEM', '-fsanitize=address', '-s', 'ALLOW_MEMORY_GROWTH=1'])
+    self.do_other_test('mmap_and_munmap_anonymous', emcc_args=['-s', 'NO_FILESYSTEM', '-fsanitize=address', '-s', 'ALLOW_MEMORY_GROWTH=1', '-sINITIAL_MEMORY=314572800'])
 
   def test_mmap_memorygrowth(self):
     self.do_other_test('mmap_memorygrowth', ['-s', 'ALLOW_MEMORY_GROWTH=1'])