diff --git a/os/common/startup/ARM/compilers/GCC/rules.mk b/os/common/startup/ARM/compilers/GCC/rules.mk
index 1b8a2df38..f0ae61540 100644
--- a/os/common/startup/ARM/compilers/GCC/rules.mk
+++ b/os/common/startup/ARM/compilers/GCC/rules.mk
@@ -23,8 +23,12 @@ ifneq ($(USE_LDOPT),)
 endif
 
 # Link time optimizations
-ifeq ($(USE_LTO),yes)
-  OPT += -flto=auto
+ifneq ($(USE_LTO),no)
+  ifeq ($(USE_LTO),yes)
+    OPT += -flto
+  else
+    OPT += -flto=$(USE_LTO)
+  endif
 endif
 
 # Undefined state stack size
diff --git a/os/common/startup/ARMCMx/compilers/GCC/mk/rules.mk b/os/common/startup/ARMCMx/compilers/GCC/mk/rules.mk
index 1783f87ea..27a49149c 100644
--- a/os/common/startup/ARMCMx/compilers/GCC/mk/rules.mk
+++ b/os/common/startup/ARMCMx/compilers/GCC/mk/rules.mk
@@ -23,8 +23,12 @@ ifneq ($(USE_LDOPT),)
 endif
 
 # Link time optimizations
-ifeq ($(USE_LTO),yes)
-  OPT += -flto=auto
+ifneq ($(USE_LTO),no)
+  ifeq ($(USE_LTO),yes)
+    OPT += -flto
+  else
+    OPT += -flto=$(USE_LTO)
+  endif
 endif
 
 # FPU options default (Cortex-M4 and Cortex-M7 single precision).
diff --git a/os/common/startup/SIMIA32/compilers/GCC/rules.mk b/os/common/startup/SIMIA32/compilers/GCC/rules.mk
index 1dcd83c20..1c134dd14 100644
--- a/os/common/startup/SIMIA32/compilers/GCC/rules.mk
+++ b/os/common/startup/SIMIA32/compilers/GCC/rules.mk
@@ -23,8 +23,12 @@ ifneq ($(USE_LDOPT),)
 endif
 
 # Link time optimizations
-ifeq ($(USE_LTO),yes)
-  OPT += -flto=auto
+ifneq ($(USE_LTO),no)
+  ifeq ($(USE_LTO),yes)
+    OPT += -flto
+  else
+    OPT += -flto=$(USE_LTO)
+  endif
 endif
 
 # Output directory and files