diff --git a/doc/jemalloc.xml.in b/doc/jemalloc.xml.in
index e8a5722..cec85b5 100644
--- a/doc/jemalloc.xml.in
+++ b/doc/jemalloc.xml.in
@@ -51,12 +51,23 @@
     <para>This manual describes jemalloc @jemalloc_version@.  More information
     can be found at the <ulink
     url="http://www.canonware.com/jemalloc/">jemalloc website</ulink>.</para>
+
+    <para>The following configuration options are enabled in libc's built-in
+    jemalloc: <option>--enable-dss</option>,
+    <option>--enable-experimental</option>, <option>--enable-fill</option>,
+    <option>--enable-lazy-lock</option>, <option>--enable-munmap</option>,
+    <option>--enable-stats</option>, <option>--enable-tcache</option>,
+    <option>--enable-tls</option>, <option>--enable-utrace</option>, and
+    <option>--enable-xmalloc</option>.  Additionally,
+    <option>--enable-debug</option> is enabled in development versions of
+    FreeBSD (controlled by the <constant>MALLOC_PRODUCTION</constant> make
+    variable).</para>
   </refsect1>
   <refsynopsisdiv>
     <title>SYNOPSIS</title>
     <funcsynopsis>
       <funcsynopsisinfo>#include &lt;<filename class="headerfile">stdlib.h</filename>&gt;
-#include &lt;<filename class="headerfile">jemalloc/jemalloc.h</filename>&gt;</funcsynopsisinfo>
+#include &lt;<filename class="headerfile">malloc_np.h</filename>&gt;</funcsynopsisinfo>
       <refsect2>
         <title>Standard API</title>
         <funcprototype>
@@ -2091,4 +2102,16 @@ malloc_conf = "lg_chunk:24";]]></programlisting></para>
     <para>The <function>posix_memalign<parameter/></function> function conforms
     to IEEE Std 1003.1-2001 (&ldquo;POSIX.1&rdquo;).</para>
   </refsect1>
+  <refsect1 id="history">
+    <title>HISTORY</title>
+    <para>The <function>malloc_usable_size<parameter/></function> and
+    <function>posix_memalign<parameter/></function> functions first appeared in
+    FreeBSD 7.0.</para>
+
+    <para>The <function>aligned_alloc<parameter/></function>,
+    <function>malloc_stats_print<parameter/></function>,
+    <function>mallctl*<parameter/></function>, and
+    <function>*allocm<parameter/></function> functions first appeared in
+    FreeBSD 10.0.</para>
+  </refsect1>
 </refentry>
diff --git a/include/jemalloc/internal/jemalloc_internal.h.in b/include/jemalloc/internal/jemalloc_internal.h.in
index b61abe8..edbb437 100644
--- a/include/jemalloc/internal/jemalloc_internal.h.in
+++ b/include/jemalloc/internal/jemalloc_internal.h.in
@@ -1,5 +1,8 @@
 #ifndef JEMALLOC_INTERNAL_H
 #define JEMALLOC_INTERNAL_H
+#include "libc_private.h"
+#include "namespace.h"
+
 #include <sys/mman.h>
 #include <sys/param.h>
 #include <sys/syscall.h>
@@ -35,6 +38,9 @@
 #include <pthread.h>
 #include <math.h>
 
+#include "un-namespace.h"
+#include "libc_private.h"
+
 #define	JEMALLOC_NO_DEMANGLE
 #include "../jemalloc@install_suffix@.h"
 
diff --git a/include/jemalloc/internal/mutex.h b/include/jemalloc/internal/mutex.h
index 8837ef5..d7133f4 100644
--- a/include/jemalloc/internal/mutex.h
+++ b/include/jemalloc/internal/mutex.h
@@ -39,9 +39,6 @@ struct malloc_mutex_s {
 
 #ifdef JEMALLOC_LAZY_LOCK
 extern bool isthreaded;
-#else
-#  undef isthreaded /* Undo private_namespace.h definition. */
-#  define isthreaded true
 #endif
 
 bool	malloc_mutex_init(malloc_mutex_t *mutex);
diff --git a/include/jemalloc/internal/private_namespace.h b/include/jemalloc/internal/private_namespace.h
index bb1b63e..00eb169 100644
--- a/include/jemalloc/internal/private_namespace.h
+++ b/include/jemalloc/internal/private_namespace.h
@@ -165,7 +165,6 @@
 #define	iqalloc JEMALLOC_N(iqalloc)
 #define	iralloc JEMALLOC_N(iralloc)
 #define	isalloc JEMALLOC_N(isalloc)
-#define	isthreaded JEMALLOC_N(isthreaded)
 #define	ivsalloc JEMALLOC_N(ivsalloc)
 #define	jemalloc_postfork_child JEMALLOC_N(jemalloc_postfork_child)
 #define	jemalloc_postfork_parent JEMALLOC_N(jemalloc_postfork_parent)
diff --git a/include/jemalloc/jemalloc.h.in b/include/jemalloc/jemalloc.h.in
index f0581db..f26d8bc 100644
--- a/include/jemalloc/jemalloc.h.in
+++ b/include/jemalloc/jemalloc.h.in
@@ -15,6 +15,7 @@ extern "C" {
 #define	JEMALLOC_VERSION_GID "@jemalloc_version_gid@"
 
 #include "jemalloc_defs@install_suffix@.h"
+#include "jemalloc_FreeBSD.h"
 
 #ifdef JEMALLOC_EXPERIMENTAL
 #define	ALLOCM_LG_ALIGN(la)	(la)
diff --git a/include/jemalloc/jemalloc_FreeBSD.h b/include/jemalloc/jemalloc_FreeBSD.h
new file mode 100644
index 0000000..2c5797f
--- /dev/null
+++ b/include/jemalloc/jemalloc_FreeBSD.h
@@ -0,0 +1,76 @@
+/*
+ * Override settings that were generated in jemalloc_defs.h as necessary.
+ */
+
+#undef JEMALLOC_OVERRIDE_VALLOC
+
+#ifndef MALLOC_PRODUCTION
+#define	JEMALLOC_DEBUG
+#endif
+
+/*
+ * The following are architecture-dependent, so conditionally define them for
+ * each supported architecture.
+ */
+#undef CPU_SPINWAIT
+#undef JEMALLOC_TLS_MODEL
+#undef STATIC_PAGE_SHIFT
+#undef LG_SIZEOF_PTR
+#undef LG_SIZEOF_INT
+#undef LG_SIZEOF_LONG
+#undef LG_SIZEOF_INTMAX_T
+
+#ifdef __i386__
+#  define LG_SIZEOF_PTR		2
+#  define CPU_SPINWAIT		__asm__ volatile("pause")
+#  define JEMALLOC_TLS_MODEL	__attribute__((tls_model("initial-exec")))
+#endif
+#ifdef __ia64__
+#  define LG_SIZEOF_PTR		3
+#endif
+#ifdef __sparc64__
+#  define LG_SIZEOF_PTR		3
+#  define JEMALLOC_TLS_MODEL	__attribute__((tls_model("initial-exec")))
+#endif
+#ifdef __amd64__
+#  define LG_SIZEOF_PTR		3
+#  define CPU_SPINWAIT		__asm__ volatile("pause")
+#  define JEMALLOC_TLS_MODEL	__attribute__((tls_model("initial-exec")))
+#endif
+#ifdef __arm__
+#  define LG_SIZEOF_PTR		2
+#endif
+#ifdef __mips__
+#  define LG_SIZEOF_PTR		2
+#endif
+#ifdef __powerpc64__
+#  define LG_SIZEOF_PTR		3
+#elif defined(__powerpc__)
+#  define LG_SIZEOF_PTR		2
+#endif
+
+#ifndef JEMALLOC_TLS_MODEL
+#  define JEMALLOC_TLS_MODEL	/* Default. */
+#endif
+#ifdef __clang__
+#  undef JEMALLOC_TLS_MODEL
+#  define JEMALLOC_TLS_MODEL	/* clang does not support tls_model yet. */
+#endif
+
+#define	STATIC_PAGE_SHIFT	PAGE_SHIFT
+#define	LG_SIZEOF_INT		2
+#define	LG_SIZEOF_LONG		LG_SIZEOF_PTR
+#define	LG_SIZEOF_INTMAX_T	3
+
+/* Disable lazy-lock machinery, mangle isthreaded, and adjust its type. */
+#undef JEMALLOC_LAZY_LOCK
+extern int __isthreaded;
+#define	isthreaded		((bool)__isthreaded)
+
+/* Mangle. */
+#define	open			_open
+#define	read			_read
+#define	write			_write
+#define	close			_close
+#define	pthread_mutex_lock	_pthread_mutex_lock
+#define	pthread_mutex_unlock	_pthread_mutex_unlock
diff --git a/src/jemalloc.c b/src/jemalloc.c
index f9c8916..8e24a5a 100644
--- a/src/jemalloc.c
+++ b/src/jemalloc.c
@@ -8,6 +8,9 @@ malloc_tsd_data(, arenas, arena_t *, NULL)
 malloc_tsd_data(, thread_allocated, thread_allocated_t,
     THREAD_ALLOCATED_INITIALIZER)
 
+const char	*__malloc_options_1_0;
+__sym_compat(_malloc_options, __malloc_options_1_0, FBSD_1.0);
+
 /* Runtime configuration options. */
 const char	*je_malloc_conf JEMALLOC_ATTR(visibility("default"));
 #ifdef JEMALLOC_DEBUG
@@ -401,7 +404,8 @@ malloc_conf_init(void)
 #endif
 			    ;
 
-			if ((opts = getenv(envname)) != NULL) {
+			if (issetugid() == 0 && (opts = getenv(envname)) !=
+			    NULL) {
 				/*
 				 * Do nothing; opts is already initialized to
 				 * the value of the MALLOC_CONF environment
diff --git a/src/mutex.c b/src/mutex.c
index 4b8ce57..7be5fc9 100644
--- a/src/mutex.c
+++ b/src/mutex.c
@@ -63,6 +63,17 @@ pthread_create(pthread_t *__restrict thread,
 #ifdef JEMALLOC_MUTEX_INIT_CB
 int	_pthread_mutex_init_calloc_cb(pthread_mutex_t *mutex,
     void *(calloc_cb)(size_t, size_t));
+
+__weak_reference(_pthread_mutex_init_calloc_cb_stub,
+    _pthread_mutex_init_calloc_cb);
+
+int
+_pthread_mutex_init_calloc_cb_stub(pthread_mutex_t *mutex,
+    void *(calloc_cb)(size_t, size_t))
+{
+
+	return (0);
+}
 #endif
 
 bool
diff --git a/src/util.c b/src/util.c
index 99ae26d..b80676c 100644
--- a/src/util.c
+++ b/src/util.c
@@ -60,6 +60,22 @@ wrtmessage(void *cbopaque, const char *s)
 void	(*je_malloc_message)(void *, const char *s)
     JEMALLOC_ATTR(visibility("default")) = wrtmessage;
 
+JEMALLOC_CATTR(visibility("hidden"), static)
+void
+wrtmessage_1_0(const char *s1, const char *s2, const char *s3,
+    const char *s4)
+{
+
+	wrtmessage(NULL, s1);
+	wrtmessage(NULL, s2);
+	wrtmessage(NULL, s3);
+	wrtmessage(NULL, s4);
+}
+
+void	(*__malloc_message_1_0)(const char *s1, const char *s2, const char *s3,
+    const char *s4) = wrtmessage_1_0;
+__sym_compat(_malloc_message, __malloc_message_1_0, FBSD_1.0);
+
 /*
  * glibc provides a non-standard strerror_r() when _GNU_SOURCE is defined, so
  * provide a wrapper.