diff --git a/memory/build/malloc_decls.h b/memory/build/malloc_decls.h
index fee2b0792624..50c16176c57d 100644
--- a/memory/build/malloc_decls.h
+++ b/memory/build/malloc_decls.h
@@ -20,25 +20,19 @@
 #define MALLOC_FUNCS_MALLOC                                                    \
   (MALLOC_FUNCS_MALLOC_BASE | MALLOC_FUNCS_MALLOC_EXTRA)
 #define MALLOC_FUNCS_JEMALLOC 4
-#define MALLOC_FUNCS_INIT 8
-#define MALLOC_FUNCS_ARENA_BASE 16
-#define MALLOC_FUNCS_ARENA_ALLOC 32
+#define MALLOC_FUNCS_ARENA_BASE 8
+#define MALLOC_FUNCS_ARENA_ALLOC 16
 #define MALLOC_FUNCS_ARENA (MALLOC_FUNCS_ARENA_BASE | MALLOC_FUNCS_ARENA_ALLOC)
 #define MALLOC_FUNCS_ALL                                                       \
-  (MALLOC_FUNCS_INIT | MALLOC_FUNCS_MALLOC | MALLOC_FUNCS_JEMALLOC |           \
-   MALLOC_FUNCS_ARENA)
+  (MALLOC_FUNCS_MALLOC | MALLOC_FUNCS_JEMALLOC | MALLOC_FUNCS_ARENA)
 
 #endif // malloc_decls_h
 
 #ifndef MALLOC_FUNCS
-#define MALLOC_FUNCS                                                           \
-  (MALLOC_FUNCS_MALLOC | MALLOC_FUNCS_JEMALLOC | MALLOC_FUNCS_ARENA)
+#define MALLOC_FUNCS MALLOC_FUNCS_ALL
 #endif
 
 #ifdef MALLOC_DECL
-#if MALLOC_FUNCS & MALLOC_FUNCS_INIT
-MALLOC_DECL(init, void, malloc_table_t*, struct ReplaceMallocBridge**)
-#endif
 #if MALLOC_FUNCS & MALLOC_FUNCS_MALLOC_BASE
 MALLOC_DECL(malloc, void*, size_t)
 MALLOC_DECL(calloc, void*, size_t, size_t)
diff --git a/memory/build/mozjemalloc.cpp b/memory/build/mozjemalloc.cpp
index faadfba45901..51d48088ed6e 100644
--- a/memory/build/mozjemalloc.cpp
+++ b/memory/build/mozjemalloc.cpp
@@ -4812,8 +4812,9 @@ static
 // the zygote.
 #ifdef XP_DARWIN
 #define MOZ_REPLACE_WEAK __attribute__((weak_import))
-#elif defined(XP_WIN) || defined(MOZ_WIDGET_ANDROID)
-#define MOZ_NO_REPLACE_FUNC_DECL
+#elif defined(XP_WIN) || defined(ANDROID)
+#define MOZ_DYNAMIC_REPLACE_INIT
+#define replace_init replace_init_decl
 #elif defined(__GNUC__)
 #define MOZ_REPLACE_WEAK __attribute__((weak))
 #endif
@@ -4826,12 +4827,10 @@ static malloc_table_t gReplaceMallocTable = {
 #include "malloc_decls.h"
 };
 
-#ifdef MOZ_NO_REPLACE_FUNC_DECL
-#define MALLOC_DECL(name, return_type, ...)                                    \
-  typedef return_type(name##_impl_t)(__VA_ARGS__);                             \
-  name##_impl_t* replace_##name = nullptr;
-#define MALLOC_FUNCS MALLOC_FUNCS_INIT
-#include "malloc_decls.h"
+#ifdef MOZ_DYNAMIC_REPLACE_INIT
+#undef replace_init
+typedef decltype(replace_init_decl) replace_init_impl_t;
+static replace_init_impl_t* replace_init = nullptr;
 #endif
 
 #ifdef XP_WIN
@@ -4849,8 +4848,8 @@ replace_malloc_handle()
   return nullptr;
 }
 
-#define REPLACE_MALLOC_GET_FUNC(handle, name)                                  \
-  (name##_impl_t*)GetProcAddress(handle, "replace_" #name)
+#define REPLACE_MALLOC_GET_INIT_FUNC(handle)                                   \
+  (replace_init_impl_t*)GetProcAddress(handle, "replace_init")
 
 #elif defined(ANDROID)
 #include <dlfcn.h>
@@ -4867,8 +4866,8 @@ replace_malloc_handle()
   return nullptr;
 }
 
-#define REPLACE_MALLOC_GET_FUNC(handle, name)                                  \
-  (name##_impl_t*)dlsym(handle, "replace_" #name)
+#define REPLACE_MALLOC_GET_INIT_FUNC(handle)                                   \
+  (replace_init_impl_t*)dlsym(handle, "replace_init")
 
 #endif
 
@@ -4882,14 +4881,10 @@ static ReplaceMallocBridge* gReplaceMallocBridge = nullptr;
 static void
 init()
 {
-#ifdef MOZ_NO_REPLACE_FUNC_DECL
+#ifdef MOZ_DYNAMIC_REPLACE_INIT
   replace_malloc_handle_t handle = replace_malloc_handle();
   if (handle) {
-#define MALLOC_DECL(name, ...)                                                 \
-  replace_##name = REPLACE_MALLOC_GET_FUNC(handle, name);
-
-#define MALLOC_FUNCS MALLOC_FUNCS_INIT
-#include "malloc_decls.h"
+    replace_init = REPLACE_MALLOC_GET_INIT_FUNC(handle);
   }
 #endif
 
diff --git a/memory/build/replace_malloc.h b/memory/build/replace_malloc.h
index 8e541c4c3998..014ddfd7be08 100644
--- a/memory/build/replace_malloc.h
+++ b/memory/build/replace_malloc.h
@@ -80,29 +80,21 @@
 
 MOZ_BEGIN_EXTERN_C
 
-// MOZ_NO_REPLACE_FUNC_DECL and MOZ_REPLACE_WEAK are only defined in
-// replace_malloc.c. Normally including this header will add function
-// definitions.
-#ifndef MOZ_NO_REPLACE_FUNC_DECL
-
+// MOZ_REPLACE_WEAK is only defined in mozjemalloc.cpp. Normally including
+// this header will add function definitions.
 #ifndef MOZ_REPLACE_WEAK
 #define MOZ_REPLACE_WEAK
 #endif
 
-// Export replace_init.
-#define MALLOC_DECL(name, return_type, ...)                                    \
-  MOZ_EXPORT return_type replace_##name(__VA_ARGS__) MOZ_REPLACE_WEAK;
+// Replace-malloc library initialization function. See top of this file
+MOZ_EXPORT void
+replace_init(malloc_table_t*, struct ReplaceMallocBridge**) MOZ_REPLACE_WEAK;
 
-#define MALLOC_FUNCS MALLOC_FUNCS_INIT
-#include "malloc_decls.h"
-
-// Define the remaining replace_* functions as not exported.
+// Define the replace_* functions as not exported.
 #define MALLOC_DECL(name, return_type, ...)                                    \
   return_type replace_##name(__VA_ARGS__);
 #include "malloc_decls.h"
 
-#endif // MOZ_NO_REPLACE_FUNC_DECL
-
 MOZ_END_EXTERN_C
 
 #endif // replace_malloc_h