diff --git a/Makefile b/Makefile
index 541e942ed5..27375f033f 100644
--- a/Makefile
+++ b/Makefile
@@ -643,6 +643,13 @@ export CFLAGS_EFI	# Compiler flags to add when building EFI app
 export CFLAGS_NON_EFI	# Compiler flags to remove when building EFI app
 export EFI_TARGET	# binutils target if EFI is natively supported
 
+export LTO_ENABLE
+
+# This is y if LTO is enabled for this build. See NO_LTO=1 to disable LTO
+ifeq ($(NO_LTO),)
+LTO_ENABLE=$(if $(CONFIG_LTO),y)
+endif
+
 # If board code explicitly specified LDSCRIPT or CONFIG_SYS_LDSCRIPT, use
 # that (or fail if absent).  Otherwise, search for a linker script in a
 # standard location.
@@ -708,16 +715,16 @@ endif
 LTO_CFLAGS :=
 LTO_FINAL_LDFLAGS :=
 export LTO_CFLAGS LTO_FINAL_LDFLAGS
-ifdef CONFIG_LTO
+ifeq ($(LTO_ENABLE),y)
 	ifeq ($(cc-name),clang)
-		LTO_CFLAGS		+= -flto
+		LTO_CFLAGS		+= -DLTO_ENABLE -flto
 		LTO_FINAL_LDFLAGS	+= -flto
 
 		AR			= $(shell $(CC) -print-prog-name=llvm-ar)
 		NM			= $(shell $(CC) -print-prog-name=llvm-nm)
 	else
 		NPROC			:= $(shell nproc 2>/dev/null || echo 1)
-		LTO_CFLAGS		+= -flto=$(NPROC)
+		LTO_CFLAGS		+= -DLTO_ENABLE -flto=$(NPROC)
 		LTO_FINAL_LDFLAGS	+= -fuse-linker-plugin -flto=$(NPROC)
 
 		# use plugin aware tools
@@ -1765,7 +1772,7 @@ ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(ARCH)/Makefile.postlink)
 
 # Generate linker list symbols references to force compiler to not optimize
 # them away when compiling with LTO
-ifdef CONFIG_LTO
+ifeq ($(LTO_ENABLE),y)
 u-boot-keep-syms-lto := keep-syms-lto.o
 u-boot-keep-syms-lto_c := $(patsubst %.o,%.c,$(u-boot-keep-syms-lto))
 
@@ -1787,7 +1794,7 @@ endif
 
 # Rule to link u-boot
 # May be overridden by arch/$(ARCH)/config.mk
-ifdef CONFIG_LTO
+ifeq ($(LTO_ENABLE),y)
 quiet_cmd_u-boot__ ?= LTO     $@
       cmd_u-boot__ ?=								\
 		$(CC) -nostdlib -nostartfiles					\
diff --git a/arch/arm/config.mk b/arch/arm/config.mk
index b3548ce243..2065438d05 100644
--- a/arch/arm/config.mk
+++ b/arch/arm/config.mk
@@ -15,11 +15,11 @@ CFLAGS_NON_EFI := -fno-pic -ffixed-r9 -ffunction-sections -fdata-sections \
 		  -fstack-protector-strong
 CFLAGS_EFI := -fpic -fshort-wchar
 
-ifneq ($(CONFIG_LTO)$(CONFIG_USE_PRIVATE_LIBGCC),yy)
+ifneq ($(LTO_ENABLE)$(CONFIG_USE_PRIVATE_LIBGCC),yy)
 LDFLAGS_FINAL += --gc-sections
 endif
 
-ifndef CONFIG_LTO
+ifneq ($(LTO_ENABLE),y)
 PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections
 endif
 
diff --git a/arch/arm/include/asm/global_data.h b/arch/arm/include/asm/global_data.h
index 6ee2a76761..cd6112dfcd 100644
--- a/arch/arm/include/asm/global_data.h
+++ b/arch/arm/include/asm/global_data.h
@@ -101,7 +101,7 @@ struct arch_global_data {
 
 #include <asm-generic/global_data.h>
 
-#if defined(__clang__) || defined(CONFIG_LTO)
+#if defined(__clang__) || defined(LTO_ENABLE)
 
 #define DECLARE_GLOBAL_DATA_PTR
 #define gd	get_gd()
diff --git a/doc/build/gcc.rst b/doc/build/gcc.rst
index ee544ad87e..a71f860a48 100644
--- a/doc/build/gcc.rst
+++ b/doc/build/gcc.rst
@@ -152,6 +152,23 @@ of dtc is new enough. It also makes sure that pylibfdt is present, if needed
 Note that the :doc:`tools` are always built with the included version of libfdt
 so it is not possible to build U-Boot tools with a system libfdt, at present.
 
+Link-time optimisation (LTO)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+U-Boot supports link-time optimisation which can reduce the size of the final
+U-Boot binaries, particularly with SPL.
+
+At present this can be enabled by ARM boards by adding `CONFIG_LTO=y` into the
+defconfig file. Other architectures are not supported. LTO is enabled by default
+for sandbox.
+
+This does incur a link-time penalty of several seconds. For faster incremental
+builds during development, you can disable it by setting `NO_LTO` to `1`.
+
+.. code-block:: bash
+
+    NO_LTO=1 make
+
 Other build targets
 ~~~~~~~~~~~~~~~~~~~
 
diff --git a/scripts/Makefile.spl b/scripts/Makefile.spl
index 3bafeb4fe9..0b3a51da13 100644
--- a/scripts/Makefile.spl
+++ b/scripts/Makefile.spl
@@ -489,7 +489,7 @@ endif
 
 # Rule to link u-boot-spl
 # May be overridden by arch/$(ARCH)/config.mk
-ifdef CONFIG_LTO
+ifeq ($(LTO_ENABLE),y)
 quiet_cmd_u-boot-spl ?= LTO     $@
       cmd_u-boot-spl ?= \
 	(									\