diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index 406445a358..fa97d4cccc 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -307,6 +307,22 @@ config MEM_SHARING
 	bool "Xen memory sharing support (UNSUPPORTED)" if UNSUPPORTED
 	depends on HVM
 
+config REQUIRE_NX
+	bool "Require NX bit support"
+	help
+	  No-eXecute (also called XD "eXecute Disable" and DEP "Data
+	  Execution Prevention") is a security feature designed originally
+	  to combat buffer overflow attacks by marking regions of memory
+	  which the CPU must not interpret as instructions.
+
+	  The NX feature exists in every 64bit CPU except for some very
+	  early Pentium 4 Prescott machines.
+
+	  Enabling this option will improve Xen's security by removing
+	  cases where Xen could be tricked into thinking that the feature
+	  was unavailable. However, if enabled, Xen will no longer boot on
+	  any CPU which is lacking NX support.
+
 endmenu
 
 source "common/Kconfig"
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index ce62eae6f3..ec1e80ef68 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -123,6 +123,7 @@ multiboot2_header:
 .Lbad_ldr_nih: .asciz "ERR: EFI ImageHandle is not provided by bootloader!"
 .Lbad_efi_msg: .asciz "ERR: EFI IA-32 platforms are not supported!"
 .Lbag_alg_msg: .asciz "ERR: Xen must be loaded at a 2Mb boundary!"
+.Lno_nx_bit_msg: .asciz "ERR: Not an NX-bit capable CPU!"
 
         .section .init.data, "aw", @progbits
         .align 4
@@ -151,6 +152,11 @@ not_multiboot:
 .Lnot_aligned:
         add     $sym_offs(.Lbag_alg_msg),%esi   # Error message
         jmp     .Lget_vtb
+#ifdef CONFIG_REQUIRE_NX
+.Lno_nx_bit:
+        add     $sym_offs(.Lno_nx_bit_msg),%esi
+        jmp     .Lget_vtb
+#endif
 .Lmb2_no_st:
         /*
          * Here we are on EFI platform. vga_text_buffer was zapped earlier
@@ -651,7 +657,12 @@ trampoline_setup:
         bt      $cpufeat_bit(X86_FEATURE_LM),%edx
         jnc     .Lbad_cpu
 
-        /* Check for NX */
+        /*
+         * Check for NX
+         *   - If Xen was compiled requiring it simply assert it's
+         *     supported. The trampoline already has the right constant.
+         *   - Otherwise, update the trampoline EFER mask accordingly.
+         */
         bt      $cpufeat_bit(X86_FEATURE_NX), %edx
         jc     .Lhas_nx_bit
 
@@ -697,9 +708,11 @@ trampoline_setup:
         jnc     .Lno_nx_bit
 
 .Lhas_nx_bit:
+#ifndef CONFIG_REQUIRE_NX
         /* Adjust EFER is NX is present */
         orb     $EFER_NXE >> 8, 1 + sym_esi(trampoline_efer)
 .Lno_nx_bit:
+#endif
 
         /* Stash TSC to calculate a good approximation of time-since-boot */
         rdtsc
diff --git a/xen/arch/x86/boot/trampoline.S b/xen/arch/x86/boot/trampoline.S
index c6005fa33d..b8ab0ffdcb 100644
--- a/xen/arch/x86/boot/trampoline.S
+++ b/xen/arch/x86/boot/trampoline.S
@@ -147,7 +147,8 @@ GLOBAL(trampoline_misc_enable_off)
 
 /* EFER OR-mask for boot paths.  SCE conditional on PV support, NX added when available. */
 GLOBAL(trampoline_efer)
-        .long   EFER_LME | (EFER_SCE * IS_ENABLED(CONFIG_PV))
+        .long   EFER_LME | (EFER_SCE * IS_ENABLED(CONFIG_PV)) | \
+                (EFER_NXE * IS_ENABLED(CONFIG_REQUIRE_NX))
 
 GLOBAL(trampoline_xen_phys_start)
         .long   0
diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index c94e53d139..84700559bb 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -751,6 +751,15 @@ static void __init efi_arch_cpu(void)
     {
         caps[FEATURESET_e1d] = cpuid_edx(0x80000001);
 
+        /*
+         * This check purposefully doesn't use cpu_has_nx because
+         * cpu_has_nx bypasses the boot_cpu_data read if Xen was compiled
+         * with CONFIG_REQUIRE_NX
+         */
+        if ( IS_ENABLED(CONFIG_REQUIRE_NX) &&
+             !boot_cpu_has(X86_FEATURE_NX) )
+            blexit(L"This Xen build requires NX bit support.");
+
         if ( cpu_has_nx )
             trampoline_efer |= EFER_NXE;
     }
diff --git a/xen/arch/x86/include/asm/cpufeature.h b/xen/arch/x86/include/asm/cpufeature.h
index ace31e3b1f..610532da43 100644
--- a/xen/arch/x86/include/asm/cpufeature.h
+++ b/xen/arch/x86/include/asm/cpufeature.h
@@ -91,7 +91,8 @@ static inline bool boot_cpu_has(unsigned int feat)
 #define cpu_has_hypervisor      boot_cpu_has(X86_FEATURE_HYPERVISOR)
 
 /* CPUID level 0x80000001.edx */
-#define cpu_has_nx              boot_cpu_has(X86_FEATURE_NX)
+#define cpu_has_nx              (IS_ENABLED(CONFIG_REQUIRE_NX) || \
+                                 boot_cpu_has(X86_FEATURE_NX))
 #define cpu_has_page1gb         boot_cpu_has(X86_FEATURE_PAGE1GB)
 #define cpu_has_rdtscp          boot_cpu_has(X86_FEATURE_RDTSCP)
 #define cpu_has_3dnow_ext       boot_cpu_has(X86_FEATURE_3DNOWEXT)
