Index: stand/efi/fdt/efi_fdt.c
===================================================================
--- stand/efi/fdt/efi_fdt.c
+++ stand/efi/fdt/efi_fdt.c
@@ -53,12 +53,7 @@
 		return (1);
 	printf("Using DTB provided by EFI at %p.\n", hdr);
 
-	s = getenv("fdt_overlays");
-	if (s != NULL && *s != '\0') {
-		printf("Loading DTB overlays: '%s'\n", s);
-		fdt_load_dtb_overlays(s);
-	}
-
+	fdt_load_dtb_overlays(NULL);
 	return (0);
 }
 
Index: stand/fdt/fdt_loader_cmd.c
===================================================================
--- stand/fdt/fdt_loader_cmd.c
+++ stand/fdt/fdt_loader_cmd.c
@@ -73,6 +73,7 @@
 static vm_offset_t fdtp_va = 0;
 
 static int fdt_load_dtb(vm_offset_t va);
+static int fdt_load_dtb_overlays_string(const char * filenames);
 
 static int fdt_cmd_nyi(int argc, char *argv[]);
 
@@ -310,14 +311,14 @@
 	return (0);
 }
 
-int
-fdt_load_dtb_overlays(const char * filenames)
+static int
+fdt_load_dtb_overlays_string(const char * filenames)
 {
 	char *names;
 	char *name;
 	char *comaptr;
 
-	debugf("fdt_load_dtb_overlay(%s)\n", filenames);
+	debugf("fdt_load_dtb_overlays_string(%s)\n", filenames);
 
 	names = strdup(filenames);
 	if (names == NULL)
@@ -794,6 +795,28 @@
 	}
 }
 
+void
+fdt_load_dtb_overlays(FDT_ADDITIONAL_OVERLAY_FUNC fdt_additional_overlays)
+{
+	const char *s;
+
+	/* Any extra overlays supplied by pre-loader environment */
+	if (fdt_additional_overlays != NULL) {
+		s = fdt_additional_overlays();
+		if (s != NULL && *s != '\0') {
+			printf("Loading DTB overlays: '%s'\n", s);
+			fdt_load_dtb_overlays_string(s);
+		}
+	}
+
+	/* Any overlays supplied by loader environment */
+	s = getenv("fdt_overlays");
+	if (s != NULL && *s != '\0') {
+		printf("Loading DTB overlays: '%s'\n", s);
+		fdt_load_dtb_overlays_string(s);
+	}
+}
+
 /*
  * Locate the blob, fix it up and return its location.
  */
Index: stand/fdt/fdt_platform.h
===================================================================
--- stand/fdt/fdt_platform.h
+++ stand/fdt/fdt_platform.h
@@ -38,6 +38,8 @@
 
 #define	TMP_MAX_ETH	8
 
+typedef const char *(*FDT_ADDITIONAL_OVERLAY_FUNC)(void);
+
 int fdt_copy(vm_offset_t);
 void fdt_fixup_cpubusfreqs(unsigned long, unsigned long);
 void fdt_fixup_ethernet(const char *, char *, int);
@@ -46,7 +48,7 @@
 void fdt_apply_overlays(void);
 int fdt_load_dtb_addr(struct fdt_header *);
 int fdt_load_dtb_file(const char *);
-int fdt_load_dtb_overlays(const char *);
+void fdt_load_dtb_overlays(FDT_ADDITIONAL_OVERLAY_FUNC);
 int fdt_setup_fdtp(void);
 
 /* The platform library needs to implement these functions */
Index: stand/uboot/fdt/uboot_fdt.c
===================================================================
--- stand/uboot/fdt/uboot_fdt.c
+++ stand/uboot/fdt/uboot_fdt.c
@@ -39,6 +39,8 @@
 #define STR(number) #number
 #define STRINGIFY(number) STR(number)
 
+static const char *fdt_additional_overlays(void);
+
 int
 fdt_platform_load_dtb(void)
 {
@@ -89,15 +91,8 @@
 	}
 
 exit:
-	if (rv == 0) {
-		s = getenv("fdt_overlays");
-		if (s == NULL)
-			s = ub_env_get("fdt_overlays");
-		if (s != NULL && *s != '\0') {
-			printf("Loading DTB overlays: '%s'\n", s);
-			fdt_load_dtb_overlays(s);
-		}
-	}
+	if (rv == 0)
+		fdt_load_dtb_overlays(fdt_additional_overlays);
 
 	return (rv);
 }
@@ -197,3 +192,10 @@
 	/* Fixup memory regions */
 	fdt_fixup_memory(regions, n);
 }
+
+static const char *
+fdt_additional_overlays(void)
+{
+
+	return (ub_env_get("fdt_overlays"));
+}