diff --git a/system/lib/sbrk.c b/system/lib/libc/sbrk.c
similarity index 96%
rename from system/lib/sbrk.c
rename to system/lib/libc/sbrk.c
index 21f2d570956eb..aa1410518bfd7 100644
--- a/system/lib/sbrk.c
+++ b/system/lib/libc/sbrk.c
@@ -6,6 +6,12 @@
  *
 */
 
+// libc files are compiled as -std=c99 which doesn't normally declare
+// max_align_t.
+#if __STDC_VERSION__ < 201112L
+#define __NEED_max_align_t
+#endif
+
 #ifndef EMSCRIPTEN_NO_ERRNO
 #include <errno.h>
 #endif
diff --git a/test/code_size/hello_wasm_worker_wasm.json b/test/code_size/hello_wasm_worker_wasm.json
index fd3c7cade8ae8..1c477feb0bcd4 100644
--- a/test/code_size/hello_wasm_worker_wasm.json
+++ b/test/code_size/hello_wasm_worker_wasm.json
@@ -3,8 +3,8 @@
   "a.html.gz": 433,
   "a.js": 733,
   "a.js.gz": 463,
-  "a.wasm": 1854,
-  "a.wasm.gz": 1034,
-  "total": 3324,
-  "total_gz": 1930
+  "a.wasm": 1859,
+  "a.wasm.gz": 1033,
+  "total": 3329,
+  "total_gz": 1929
 }
diff --git a/test/code_size/hello_webgl2_wasm.json b/test/code_size/hello_webgl2_wasm.json
index 8f2a7cbe7bf44..69df7d2928d07 100644
--- a/test/code_size/hello_webgl2_wasm.json
+++ b/test/code_size/hello_webgl2_wasm.json
@@ -3,8 +3,8 @@
   "a.html.gz": 379,
   "a.js": 4971,
   "a.js.gz": 2430,
-  "a.wasm": 10451,
-  "a.wasm.gz": 6680,
-  "total": 15991,
-  "total_gz": 9489
+  "a.wasm": 10459,
+  "a.wasm.gz": 6689,
+  "total": 15999,
+  "total_gz": 9498
 }
diff --git a/test/code_size/hello_webgl2_wasm2js.json b/test/code_size/hello_webgl2_wasm2js.json
index 82590513233fa..17ddaf74b7b1d 100644
--- a/test/code_size/hello_webgl2_wasm2js.json
+++ b/test/code_size/hello_webgl2_wasm2js.json
@@ -1,10 +1,10 @@
 {
   "a.html": 567,
   "a.html.gz": 379,
-  "a.js": 18201,
-  "a.js.gz": 8063,
+  "a.js": 18219,
+  "a.js.gz": 8059,
   "a.mem": 3171,
-  "a.mem.gz": 2714,
-  "total": 21939,
-  "total_gz": 11156
+  "a.mem.gz": 2713,
+  "total": 21957,
+  "total_gz": 11151
 }
diff --git a/test/code_size/hello_webgl_wasm.json b/test/code_size/hello_webgl_wasm.json
index 2e5c5d3487a3e..71d230beea6b4 100644
--- a/test/code_size/hello_webgl_wasm.json
+++ b/test/code_size/hello_webgl_wasm.json
@@ -3,8 +3,8 @@
   "a.html.gz": 379,
   "a.js": 4450,
   "a.js.gz": 2250,
-  "a.wasm": 10451,
-  "a.wasm.gz": 6680,
-  "total": 15470,
-  "total_gz": 9309
+  "a.wasm": 10459,
+  "a.wasm.gz": 6689,
+  "total": 15478,
+  "total_gz": 9318
 }
diff --git a/test/code_size/hello_webgl_wasm2js.json b/test/code_size/hello_webgl_wasm2js.json
index 0bce64c31085a..f67f4f18bae42 100644
--- a/test/code_size/hello_webgl_wasm2js.json
+++ b/test/code_size/hello_webgl_wasm2js.json
@@ -1,10 +1,10 @@
 {
   "a.html": 567,
   "a.html.gz": 379,
-  "a.js": 17673,
-  "a.js.gz": 7885,
+  "a.js": 17691,
+  "a.js.gz": 7882,
   "a.mem": 3171,
-  "a.mem.gz": 2714,
-  "total": 21411,
-  "total_gz": 10978
+  "a.mem.gz": 2713,
+  "total": 21429,
+  "total_gz": 10974
 }
diff --git a/test/other/metadce/test_metadce_hello_dylink.size b/test/other/metadce/test_metadce_hello_dylink.size
index 748b6c86252a0..22e75887797fe 100644
--- a/test/other/metadce/test_metadce_hello_dylink.size
+++ b/test/other/metadce/test_metadce_hello_dylink.size
@@ -1 +1 @@
-9486
+9488
diff --git a/test/test_core.py b/test/test_core.py
index dec35b9f46535..327f3b9b42746 100644
--- a/test/test_core.py
+++ b/test/test_core.py
@@ -1017,7 +1017,7 @@ def test_emmalloc(self, *args):
     self.set_setting('MALLOC', 'none')
     self.emcc_args += [
       '-fno-builtin',
-      path_from_root('system/lib/sbrk.c'),
+      path_from_root('system/lib/libc/sbrk.c'),
       path_from_root('system/lib/emmalloc.c')
     ]
     self.emcc_args += args
diff --git a/tools/system_libs.py b/tools/system_libs.py
index 8098052fbbba8..88f533d758c29 100644
--- a/tools/system_libs.py
+++ b/tools/system_libs.py
@@ -955,6 +955,8 @@ def get_libcall_files(self):
       path='system/lib/libc',
       filenames=['emscripten_memcpy.c', 'emscripten_memset.c',
                  'emscripten_scan_stack.c',
+                 'emscripten_get_heap_size.c',  # needed by malloc
+                 'sbrk.c',  # needed by malloc
                  'emscripten_memmove.c'])
     # Calls to iprintf can be generated during codegen. Ideally we wouldn't
     # compile these with -O2 like we do the rest of compiler-rt since its
@@ -973,7 +975,12 @@ def get_libcall_files(self):
     iprintf_files += files_in_path(
       path='system/lib/libc/musl/src/string',
       filenames=['strlen.c'])
-    return math_files + exit_files + other_files + iprintf_files
+
+    errno_files = files_in_path(
+      path='system/lib/libc/musl/src/errno',
+      filenames=['__errno_location.c'])
+
+    return math_files + exit_files + other_files + iprintf_files + errno_files
 
   def get_files(self):
     libc_files = []
@@ -1185,6 +1192,7 @@ def get_files(self):
           'sigaction.c',
           'sigtimedwait.c',
           'wasi-helpers.c',
+          'sbrk.c',
         ])
 
     if settings.RELOCATABLE:
@@ -1587,8 +1595,7 @@ def get_files(self):
     malloc = utils.path_from_root('system/lib', {
       'dlmalloc': 'dlmalloc.c', 'emmalloc': 'emmalloc.c',
     }[malloc_base])
-    sbrk = utils.path_from_root('system/lib/sbrk.c')
-    return [malloc, sbrk]
+    return [malloc]
 
   def get_cflags(self):
     cflags = super().get_cflags()