--- a/memory/mozjemalloc/mozjemalloc.cpp
+++ b/memory/mozjemalloc/mozjemalloc.cpp
@@ -307,20 +307,16 @@ void *_mmap(void *addr, size_t length, i
 #define munmap(a, l) syscall(SYS_munmap, a, l)
 #endif
 #endif
 
 #ifdef MOZ_MEMORY_DARWIN
 static pthread_key_t tlsIndex;
 #endif
 
-#if defined(MOZ_MEMORY_SOLARIS) && defined(MAP_ALIGN) && !defined(JEMALLOC_NEVER_USES_MAP_ALIGN)
-#define JEMALLOC_USES_MAP_ALIGN	 /* Required on Solaris 10. Might improve performance elsewhere. */
-#endif
-
 #ifdef MOZ_MEMORY_WINDOWS
    /* MSVC++ does not support C99 variable-length arrays. */
 #  define RB_NO_C99_VARARRAYS
 #endif
 #include "rb.h"
 
 #ifdef MOZ_DEBUG
    /* Disable inlining to make debugging easier. */
@@ -1756,37 +1752,16 @@ pages_unmap(void *addr, size_t size)
 	if (VirtualFree(addr, 0, MEM_RELEASE) == 0) {
 		_malloc_message(_getprogname(),
 		    ": (malloc) Error in VirtualFree()\n", "", "");
 		if (opt_abort)
 			moz_abort();
 	}
 }
 #else
-#ifdef JEMALLOC_USES_MAP_ALIGN
-static void *
-pages_map_align(size_t size, size_t alignment)
-{
-	void *ret;
-
-	/*
-	 * We don't use MAP_FIXED here, because it can cause the *replacement*
-	 * of existing mappings, and we only want to create new mappings.
-	 */
-	ret = mmap((void *)alignment, size, PROT_READ | PROT_WRITE,
-		MAP_PRIVATE | MAP_NOSYNC | MAP_ALIGN | MAP_ANON, -1, 0);
-	MOZ_ASSERT(ret != NULL);
-
-	if (ret == MAP_FAILED)
-		ret = NULL;
-	else
-		MozTagAnonymousMemory(ret, size, "jemalloc");
-	return (ret);
-}
-#endif
 
 static void *
 pages_map(void *addr, size_t size)
 {
 	void *ret;
 #if defined(__ia64__) || (defined(__sparc__) && defined(__arch64__) && defined(__linux__))
         /*
          * The JS engine assumes that all allocated pointers have their high 17 bits clear,
@@ -2120,19 +2095,16 @@ chunk_alloc_mmap_slow(size_t size, size_
 
         MOZ_ASSERT(ret != NULL);
         return (ret);
 }
 
 static void *
 chunk_alloc_mmap(size_t size, size_t alignment)
 {
-#ifdef JEMALLOC_USES_MAP_ALIGN
-        return pages_map_align(size, alignment);
-#else
         void *ret;
         size_t offset;
 
         /*
          * Ideally, there would be a way to specify alignment to mmap() (like
          * NetBSD has), but in the absence of such a feature, we have to work
          * hard to efficiently create aligned mappings. The reliable, but
          * slow method is to create a mapping that is over-sized, then trim the
@@ -2150,17 +2122,16 @@ chunk_alloc_mmap(size_t size, size_t ali
         offset = ALIGNMENT_ADDR2OFFSET(ret, alignment);
         if (offset != 0) {
                 pages_unmap(ret, size);
                 return (chunk_alloc_mmap_slow(size, alignment));
         }
 
         MOZ_ASSERT(ret != NULL);
         return (ret);
-#endif
 }
 
 bool
 pages_purge(void *addr, size_t length)
 {
 	bool unzeroed;
 
 #ifdef MALLOC_DECOMMIT
@@ -4825,25 +4796,16 @@ MALLOC_OUT:
 	arena_chunk_header_npages = calculate_arena_header_pages();
 	arena_maxclass = calculate_arena_maxclass();
 
 	recycle_limit = CHUNK_RECYCLE_LIMIT * chunksize;
 #endif
 
 	recycled_size = 0;
 
-#ifdef JEMALLOC_USES_MAP_ALIGN
-	/*
-	 * When using MAP_ALIGN, the alignment parameter must be a power of two
-	 * multiple of the system pagesize, or mmap will fail.
-	 */
-	MOZ_ASSERT((chunksize % pagesize) == 0);
-	MOZ_ASSERT((1 << (ffs(chunksize / pagesize) - 1)) == (chunksize/pagesize));
-#endif
-
 	/* Various sanity checks that regard configuration. */
 	MOZ_ASSERT(quantum >= sizeof(void *));
 	MOZ_ASSERT(quantum <= pagesize);
 	MOZ_ASSERT(chunksize >= pagesize);
 	MOZ_ASSERT(quantum * 4 <= chunksize);
 
 	/* Initialize chunks data. */
 	malloc_mutex_init(&chunks_mtx);