Index: head/sys/kern/link_elf.c
===================================================================
--- head/sys/kern/link_elf.c
+++ head/sys/kern/link_elf.c
@@ -736,10 +736,47 @@
 #endif
 #undef LS_PADDING
 
+/*
+ * Apply the specified protection to the loadable segments of a preloaded linker
+ * file.
+ */
 static int
-link_elf_link_preload(linker_class_t cls,
-    const char* filename, linker_file_t *result)
+preload_protect(elf_file_t ef, vm_prot_t prot)
 {
+#ifdef __amd64__
+	Elf_Ehdr *hdr;
+	Elf_Phdr *phdr, *phlimit;
+	vm_prot_t nprot;
+	int error;
+
+	error = 0;
+	hdr = (Elf_Ehdr *)ef->address;
+	phdr = (Elf_Phdr *)(ef->address + hdr->e_phoff);
+	phlimit = phdr + hdr->e_phnum;
+	for (; phdr < phlimit; phdr++) {
+		if (phdr->p_type != PT_LOAD)
+			continue;
+
+		nprot = prot | VM_PROT_READ;
+		if ((phdr->p_flags & PF_W) != 0)
+			nprot |= VM_PROT_WRITE;
+		if ((phdr->p_flags & PF_X) != 0)
+			nprot |= VM_PROT_EXECUTE;
+		error = pmap_change_prot((vm_offset_t)ef->address +
+		    phdr->p_vaddr, round_page(phdr->p_memsz), nprot);
+		if (error != 0)
+			break;
+	}
+	return (error);
+#else
+	return (0);
+#endif
+}
+
+static int
+link_elf_link_preload(linker_class_t cls, const char *filename,
+    linker_file_t *result)
+{
 	Elf_Addr *ctors_addrp;
 	Elf_Size *ctors_sizep;
 	caddr_t modptr, baseptr, sizeptr, dynptr;
@@ -798,6 +835,8 @@
 	if (error == 0)
 		error = parse_vnet(ef);
 #endif
+	if (error == 0)
+		error = preload_protect(ef, VM_PROT_ALL);
 	if (error != 0) {
 		linker_file_unload(lf, LINKER_UNLOAD_FORCE);
 		return (error);
@@ -815,6 +854,8 @@
 
 	ef = (elf_file_t) lf;
 	error = relocate_file(ef);
+	if (error == 0)
+		error = preload_protect(ef, VM_PROT_NONE);
 	if (error != 0)
 		return (error);
 	(void)link_elf_preload_parse_symbols(ef);
@@ -1274,6 +1315,7 @@
 static void
 link_elf_unload_preload(linker_file_t file)
 {
+
 	if (file->pathname != NULL)
 		preload_delete_name(file->pathname);
 }
Index: head/sys/kern/link_elf_obj.c
===================================================================
--- head/sys/kern/link_elf_obj.c
+++ head/sys/kern/link_elf_obj.c
@@ -193,7 +193,6 @@
 
 	linker_add_class(&link_elf_class);
 }
-
 SYSINIT(link_elf_obj, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, NULL);
 
 static void
@@ -209,6 +208,15 @@
 
 	if (start == end)
 		return;
+	if (ef->preloaded) {
+#ifdef __amd64__
+		error = pmap_change_prot(start, end - start, prot);
+		KASSERT(error == 0,
+		    ("link_elf_protect_range: pmap_change_prot() returned %d",
+		    error));
+#endif
+		return;
+	}
 	error = vm_map_protect(kernel_map, start, end, prot, FALSE);
 	KASSERT(error == KERN_SUCCESS,
 	    ("link_elf_protect_range: vm_map_protect() returned %d", error));
@@ -564,6 +572,14 @@
 		goto out;
 	}
 
+	/*
+	 * The file needs to be writeable and executable while applying
+	 * relocations.  Mapping protections are applied once relocation
+	 * processing is complete.
+	 */
+	link_elf_protect_range(ef, (vm_offset_t)ef->address,
+	    round_page((vm_offset_t)ef->address + ef->lf.size), VM_PROT_ALL);
+
 	/* Local intra-module relocations */
 	error = link_elf_reloc_local(lf, false);
 	if (error != 0)
@@ -616,7 +632,9 @@
 		return (error);
 #endif
 
-	/* Invoke .ctors */
+	/* Apply protections now that relocation processing is complete. */
+	link_elf_protect(ef);
+
 	link_elf_invoke_ctors(lf->ctors_addr, lf->ctors_size);
 	return (0);
 }
Index: head/sys/vm/vm_kern.c
===================================================================
--- head/sys/vm/vm_kern.c
+++ head/sys/vm/vm_kern.c
@@ -834,6 +834,14 @@
 	end = trunc_page(start + size);
 	start = round_page(start);
 
+#ifdef __amd64__
+	/*
+	 * Preloaded files do not have execute permissions by default on amd64.
+	 * Restore the default permissions to ensure that the direct map alias
+	 * is updated.
+	 */
+	pmap_change_prot(start, end - start, VM_PROT_RW);
+#endif
 	for (va = start; va < end; va += PAGE_SIZE) {
 		pa = pmap_kextract(va);
 		m = PHYS_TO_VM_PAGE(pa);