diff --git a/src/atsamd/Kconfig b/src/atsamd/Kconfig
index bc91c9a5..b847291c 100644
--- a/src/atsamd/Kconfig
+++ b/src/atsamd/Kconfig
@@ -56,11 +56,6 @@ config MCU
     default "samd51n19a" if MACH_SAMD51N19
     default "samd51p20a" if MACH_SAMD51P20
 
-config CLOCK_FREQ
-    int
-    default 48000000 if MACH_SAMD21
-    default 120000000 if MACH_SAMD51
-
 config FLASH_SIZE
     hex
     default 0x8000 if MACH_SAMD21E15
@@ -91,6 +86,27 @@ choice
         bool "Internal clock"
 endchoice
 
+choice
+    depends on MACH_SAMD51 && LOW_LEVEL_OPTIONS
+    prompt "Processor speed"
+    config SAMD51_FREQ_120
+        bool "120 MHz (standard)"
+    config SAMD51_FREQ_150
+        bool "150 MHz (overclock)"
+    config SAMD51_FREQ_180
+        bool "180 MHz (overclock)"
+    config SAMD51_FREQ_200
+        bool "200 MHz (overclock)"
+endchoice
+
+config CLOCK_FREQ
+    int
+    default 48000000 if MACH_SAMD21
+    default 150000000 if SAMD51_FREQ_150
+    default 180000000 if SAMD51_FREQ_180
+    default 200000000 if SAMD51_FREQ_200
+    default 120000000 if MACH_SAMD51
+
 choice
     prompt "Bootloader offset"
     config FLASH_START_2000
diff --git a/src/atsamd/samd51_clock.c b/src/atsamd/samd51_clock.c
index 1256ac5f..2f5062c2 100644
--- a/src/atsamd/samd51_clock.c
+++ b/src/atsamd/samd51_clock.c
@@ -13,7 +13,7 @@
 #define CLKGEN_48M 3
 #define CLKGEN_2M 4
 
-#define FREQ_MAIN 120000000
+#define FREQ_MAIN CONFIG_CLOCK_FREQ
 #define FREQ_32K 32768
 #define FREQ_48M 48000000
 #define FREQ_2M 2000000