diff --git a/subsys/bluetooth/controller/Kconfig b/subsys/bluetooth/controller/Kconfig
index 156a786512f..b8269d130b9 100644
--- a/subsys/bluetooth/controller/Kconfig
+++ b/subsys/bluetooth/controller/Kconfig
@@ -510,6 +510,12 @@ config BT_CTLR_SMI_TX
 	help
 	  Enable support for Bluetooth 5.0 SMI TX in the Controller.
 
+config BT_CTLR_SMI_TX_SETTING
+	bool "Stable modulation index - Transmitter as setting"
+	depends on BT_CTLR_SMI_TX && BT_CTLR_SETTINGS
+	help
+	  Enable support for Bluetooth 5.0 SMI TX through a system setting.
+
 if BT_LL_SW_SPLIT || BT_LL_SW_LEGACY
 
 config BT_CTLR_ADVANCED_FEATURES
diff --git a/subsys/bluetooth/controller/include/ll_feat.h b/subsys/bluetooth/controller/include/ll_feat.h
index 16ab9c1f4a5..376aea0aecd 100644
--- a/subsys/bluetooth/controller/include/ll_feat.h
+++ b/subsys/bluetooth/controller/include/ll_feat.h
@@ -91,7 +91,12 @@
 #endif /* !CONFIG_BT_CTLR_SMI_RX */
 
 #if defined(CONFIG_BT_CTLR_SMI_TX)
+#if defined(CONFIG_BT_CTLR_SMI_TX_SETTING)
+#define LL_FEAT_BIT_SMI_TX (ll_settings_smi_tx() ? \
+			    BIT64(BT_LE_FEAT_BIT_SMI_TX) : 0)
+#else /* !CONFIG_BT_CTLR_SMI_TX_SETTING */
 #define LL_FEAT_BIT_SMI_TX BIT64(BT_LE_FEAT_BIT_SMI_TX)
+#endif /* !CONFIG_BT_CTLR_SMI_TX_SETTING */
 #else /* !CONFIG_BT_CTLR_SMI_TX */
 #define LL_FEAT_BIT_SMI_TX 0
 #endif /* !CONFIG_BT_CTLR_SMI_TX */
diff --git a/subsys/bluetooth/controller/include/ll_settings.h b/subsys/bluetooth/controller/include/ll_settings.h
index d1416033806..db1f8383696 100644
--- a/subsys/bluetooth/controller/include/ll_settings.h
+++ b/subsys/bluetooth/controller/include/ll_settings.h
@@ -21,3 +21,5 @@ static inline u16_t ll_settings_subversion_number(void)
 }
 
 #endif /* CONFIG_BT_CTLR_VERSION_SETTINGS */
+
+bool ll_settings_smi_tx(void);
diff --git a/subsys/bluetooth/controller/ll_sw/ll.c b/subsys/bluetooth/controller/ll_sw/ll.c
index 392c824fcdb..07d3e7d5e3c 100644
--- a/subsys/bluetooth/controller/ll_sw/ll.c
+++ b/subsys/bluetooth/controller/ll_sw/ll.c
@@ -39,6 +39,7 @@
 #include "ll.h"
 #include "ll_feat.h"
 #include "ll_filter.h"
+#include "ll_settings.h"
 
 /* Global singletons */
 
diff --git a/subsys/bluetooth/controller/ll_sw/ll_settings.c b/subsys/bluetooth/controller/ll_sw/ll_settings.c
index 99500bf5ea8..5a10cd95224 100644
--- a/subsys/bluetooth/controller/ll_sw/ll_settings.c
+++ b/subsys/bluetooth/controller/ll_sw/ll_settings.c
@@ -32,6 +32,17 @@ u16_t ll_settings_subversion_number(void)
 
 #endif /* CONFIG_BT_CTLR_VERSION_SETTINGS */
 
+#if defined(CONFIG_BT_CTLR_SMI_TX_SETTING)
+
+static u8_t smi_tx;
+
+bool ll_settings_smi_tx(void)
+{
+	return smi_tx;
+}
+
+#endif /* CONFIG_BT_CTLR_SMI_TX_SETTING */
+
 static int ctlr_set(const char *name, size_t len_rd,
 		    settings_read_cb read_cb, void *store)
 {
@@ -63,6 +74,19 @@ static int ctlr_set(const char *name, size_t len_rd,
 	}
 #endif /* CONFIG_BT_CTLR_VERSION_SETTINGS */
 
+#if defined(CONFIG_BT_CTLR_SMI_TX_SETTING)
+	if (!strncmp(name, "smi_tx", nlen)) {
+		len = read_cb(store, &smi_tx, sizeof(smi_tx));
+		if (len < 0) {
+			BT_ERR("Failed to read SMI TX flag from storage"
+			       " (err %d)", len);
+		} else {
+			BT_DBG("SMI TX flag set to %04x", smi_tx);
+		}
+		return 0;
+	}
+#endif /* CONFIG_BT_CTLR_SMI_TX_SETTING */
+
 	return 0;
 }
 
diff --git a/subsys/bluetooth/controller/ll_sw/ull.c b/subsys/bluetooth/controller/ll_sw/ull.c
index 7feffc7845c..1d800fa6df3 100644
--- a/subsys/bluetooth/controller/ll_sw/ull.c
+++ b/subsys/bluetooth/controller/ll_sw/ull.c
@@ -32,6 +32,7 @@
 #include "pdu.h"
 #include "ll.h"
 #include "ll_feat.h"
+#include "ll_settings.h"
 #include "lll.h"
 #include "lll_adv.h"
 #include "lll_scan.h"
diff --git a/subsys/bluetooth/controller/ll_sw/ull_adv.c b/subsys/bluetooth/controller/ll_sw/ull_adv.c
index c3adb5cf6d4..6f78a7ab8d0 100644
--- a/subsys/bluetooth/controller/ll_sw/ull_adv.c
+++ b/subsys/bluetooth/controller/ll_sw/ull_adv.c
@@ -24,6 +24,7 @@
 #include "pdu.h"
 #include "ll.h"
 #include "ll_feat.h"
+#include "ll_settings.h"
 #include "lll.h"
 #include "lll_vendor.h"
 #include "lll_clock.h"
diff --git a/subsys/bluetooth/controller/ll_sw/ull_master.c b/subsys/bluetooth/controller/ll_sw/ull_master.c
index 0bc1d03f6d9..17234040c89 100644
--- a/subsys/bluetooth/controller/ll_sw/ull_master.c
+++ b/subsys/bluetooth/controller/ll_sw/ull_master.c
@@ -21,6 +21,7 @@
 #include "pdu.h"
 #include "ll.h"
 #include "ll_feat.h"
+#include "ll_settings.h"
 
 #include "lll.h"
 #include "lll_vendor.h"