diff --git a/memory/build/malloc_decls.h b/memory/build/malloc_decls.h
index 2910851bd0d8..088a2096926f 100644
--- a/memory/build/malloc_decls.h
+++ b/memory/build/malloc_decls.h
@@ -34,18 +34,31 @@
 #endif
 
 #ifdef MALLOC_DECL
+// NOTHROW_MALLOC_DECL is intended for functions where the standard library
+// declares the functions in question as `throw()`.  Not all platforms
+// consistent declare certain functions as `throw()`, though.
+
+// Bionic and OS X don't seem to care about `throw()`ness.
+#  if defined(ANDROID) || defined(XP_DARWIN)
+#    undef NOTHROW_MALLOC_DECL
+#    define NOTHROW_MALLOC_DECL MALLOC_DECL
+// Some places don't care about the distinction.
+#  elif !defined(NOTHROW_MALLOC_DECL)
+#    define NOTHROW_MALLOC_DECL MALLOC_DECL
+#  endif
+
 #  if MALLOC_FUNCS & MALLOC_FUNCS_MALLOC_BASE
 MALLOC_DECL(malloc, void*, size_t)
 MALLOC_DECL(calloc, void*, size_t, size_t)
 MALLOC_DECL(realloc, void*, void*, size_t)
-MALLOC_DECL(free, void, void*)
-MALLOC_DECL(memalign, void*, size_t, size_t)
+NOTHROW_MALLOC_DECL(free, void, void*)
+NOTHROW_MALLOC_DECL(memalign, void*, size_t, size_t)
 #  endif
 #  if MALLOC_FUNCS & MALLOC_FUNCS_MALLOC_EXTRA
-MALLOC_DECL(posix_memalign, int, void**, size_t, size_t)
-MALLOC_DECL(aligned_alloc, void*, size_t, size_t)
-MALLOC_DECL(valloc, void*, size_t)
-MALLOC_DECL(malloc_usable_size, size_t, usable_ptr_t)
+NOTHROW_MALLOC_DECL(posix_memalign, int, void**, size_t, size_t)
+NOTHROW_MALLOC_DECL(aligned_alloc, void*, size_t, size_t)
+NOTHROW_MALLOC_DECL(valloc, void*, size_t)
+NOTHROW_MALLOC_DECL(malloc_usable_size, size_t, usable_ptr_t)
 MALLOC_DECL(malloc_good_size, size_t, size_t)
 #  endif
 #  if MALLOC_FUNCS & MALLOC_FUNCS_JEMALLOC
@@ -122,5 +135,6 @@ MALLOC_DECL(moz_arena_memalign, void*, arena_id_t, size_t, size_t)
 
 #endif  // MALLOC_DECL
 
+#undef NOTHROW_MALLOC_DECL
 #undef MALLOC_DECL
 #undef MALLOC_FUNCS
diff --git a/memory/build/mozjemalloc.cpp b/memory/build/mozjemalloc.cpp
index 91dbb09e73e8..a60044cb4e23 100644
--- a/memory/build/mozjemalloc.cpp
+++ b/memory/build/mozjemalloc.cpp
@@ -4683,31 +4683,33 @@ static void replace_malloc_init_funcs(malloc_table_t* table) {
   return_type name(ARGS_HELPER(TYPED_ARGS, ##__VA_ARGS__))            \
       __attribute__((alias(MOZ_STRINGIFY(name_impl))));
 
-#define GENERIC_MALLOC_DECL2(name, name_impl, return_type, ...)   \
-  return_type name_impl(ARGS_HELPER(TYPED_ARGS, ##__VA_ARGS__)) { \
+#define GENERIC_MALLOC_DECL2(attributes, name, name_impl, return_type, ...) \
+  return_type name_impl(ARGS_HELPER(TYPED_ARGS, ##__VA_ARGS__)) attributes { \
     return DefaultMalloc::name(ARGS_HELPER(ARGS, ##__VA_ARGS__)); \
   }
 
 #ifndef __MINGW32__
-#  define GENERIC_MALLOC_DECL(name, return_type, ...) \
-    GENERIC_MALLOC_DECL2(name, name##_impl, return_type, ##__VA_ARGS__)
+#  define GENERIC_MALLOC_DECL(attributes, name, return_type, ...)        \
+    GENERIC_MALLOC_DECL2(attributes, name, name##_impl, return_type, ##__VA_ARGS__)
 #else
-#  define GENERIC_MALLOC_DECL(name, return_type, ...)                   \
-    GENERIC_MALLOC_DECL2(name, name##_impl, return_type, ##__VA_ARGS__) \
+#  define GENERIC_MALLOC_DECL(attributes, name, return_type, ...)        \
+    GENERIC_MALLOC_DECL2(attributes, name, name##_impl, return_type, ##__VA_ARGS__) \
     GENERIC_MALLOC_DECL2_MINGW(name, name##_impl, return_type, ##__VA_ARGS__)
 #endif
 
+#define NOTHROW_MALLOC_DECL(...) \
+  MOZ_MEMORY_API MACRO_CALL(GENERIC_MALLOC_DECL, (noexcept(true), __VA_ARGS__))
 #define MALLOC_DECL(...) \
-  MOZ_MEMORY_API MACRO_CALL(GENERIC_MALLOC_DECL, (__VA_ARGS__))
+  MOZ_MEMORY_API MACRO_CALL(GENERIC_MALLOC_DECL, (, __VA_ARGS__))
 #define MALLOC_FUNCS MALLOC_FUNCS_MALLOC
 #include "malloc_decls.h"
 
 #undef GENERIC_MALLOC_DECL
-#define GENERIC_MALLOC_DECL(name, return_type, ...) \
-  GENERIC_MALLOC_DECL2(name, name, return_type, ##__VA_ARGS__)
+#define GENERIC_MALLOC_DECL(attributes, name, return_type, ...)  \
+  GENERIC_MALLOC_DECL2(attributes, name, name, return_type, ##__VA_ARGS__)
 
 #define MALLOC_DECL(...) \
-  MOZ_JEMALLOC_API MACRO_CALL(GENERIC_MALLOC_DECL, (__VA_ARGS__))
+  MOZ_JEMALLOC_API MACRO_CALL(GENERIC_MALLOC_DECL, (, __VA_ARGS__))
 #define MALLOC_FUNCS (MALLOC_FUNCS_JEMALLOC | MALLOC_FUNCS_ARENA)
 #include "malloc_decls.h"
 // ***************************************************************************
diff --git a/memory/build/mozmemory.h b/memory/build/mozmemory.h
index 6b75c5b45c3a..63bb735932fc 100644
--- a/memory/build/mozmemory.h
+++ b/memory/build/mozmemory.h
@@ -50,6 +50,8 @@ static inline size_t _malloc_good_size(size_t size) {
 
 #endif
 
+#define NOTHROW_MALLOC_DECL(name, return_type, ...) \
+  MOZ_JEMALLOC_API return_type name(__VA_ARGS__) noexcept(true);
 #define MALLOC_DECL(name, return_type, ...) \
   MOZ_JEMALLOC_API return_type name(__VA_ARGS__);
 #define MALLOC_FUNCS MALLOC_FUNCS_ARENA
diff --git a/memory/build/mozmemory_wrap.cpp b/memory/build/mozmemory_wrap.cpp
index 7896df974cef..c13a4b19cf4a 100644
--- a/memory/build/mozmemory_wrap.cpp
+++ b/memory/build/mozmemory_wrap.cpp
@@ -10,6 +10,8 @@
 
 // Declare malloc implementation functions with the right return and
 // argument types.
+#define NOTHROW_MALLOC_DECL(name, return_type, ...) \
+  MOZ_MEMORY_API return_type name##_impl(__VA_ARGS__) noexcept(true);
 #define MALLOC_DECL(name, return_type, ...) \
   MOZ_MEMORY_API return_type name##_impl(__VA_ARGS__);
 #define MALLOC_FUNCS MALLOC_FUNCS_MALLOC
diff --git a/memory/mozalloc/mozalloc.h b/memory/mozalloc/mozalloc.h
index 7bce8a88587f..a80afbd5b0eb 100644
--- a/memory/mozalloc/mozalloc.h
+++ b/memory/mozalloc/mozalloc.h
@@ -16,6 +16,8 @@
 // need to use _impl suffixes, which is becoming cumbersome. We'll have to use
 // something like a malloc.h wrapper and allow the use of the functions without
 // a _impl suffix. In the meanwhile, this is enough to get by for C++ code.
+#  define NOTHROW_MALLOC_DECL(name, return_type, ...) \
+    MOZ_MEMORY_API return_type name##_impl(__VA_ARGS__) noexcept(true);
 #  define MALLOC_DECL(name, return_type, ...) \
     MOZ_MEMORY_API return_type name##_impl(__VA_ARGS__);
 #  include "malloc_decls.h"