diff --git a/cmake/extensions.cmake b/cmake/extensions.cmake
index 1e506c3572d..264884dd9b6 100644
--- a/cmake/extensions.cmake
+++ b/cmake/extensions.cmake
@@ -1309,6 +1309,66 @@ function(pow2round n)
   set(${n} ${${n}} PARENT_SCOPE)
 endfunction()
 
+# Function to create a build string based on BOARD, BOARD_REVISION, and BUILD
+# type.
+#
+# This is a common function to ensure that build strings are always created
+# in a uniform way.
+#
+# Usage:
+#   zephyr_build_string(<out-variable>
+#                       BOARD <board>
+#                       [BOARD_REVISION <revision>]
+#                       [BUILD <type>]
+#   )
+#
+# <out-variable>:            Output variable where the build string will be returned.
+# BOARD <board>:             Board name to use when creating the build string.
+# BOARD_REVISION <revision>: Board revision to use when creating the build string.
+# BUILD <type>:              Build type to use when creating the build string.
+#
+# Examples
+# calling
+#   zephyr_build_string(build_string BOARD alpha BUILD debug)
+# will return the string `alpha_debug` in `build_string` parameter.
+#
+# calling
+#   zephyr_build_string(build_string BOARD alpha BOARD_REVISION 1.0.0 BUILD debug)
+# will return the string `alpha_1_0_0_debug` in `build_string` parameter.
+#
+function(zephyr_build_string outvar)
+  set(single_args BOARD BOARD_REVISION BUILD)
+
+  cmake_parse_arguments(BUILD_STR "" "${single_args}" "" ${ARGN})
+  if(BUILD_STR_UNPARSED_ARGUMENTS)
+    message(FATAL_ERROR
+      "zephyr_build_string(${ARGV0} <val> ...) given unknown arguments:"
+      " ${BUILD_STR_UNPARSED_ARGUMENTS}"
+    )
+  endif()
+
+  if(DEFINED BUILD_STR_BOARD_REVISION AND NOT BUILD_STR_BOARD)
+    message(FATAL_ERROR
+      "zephyr_build_string(${ARGV0} <list> BOARD_REVISION ${BUILD_STR_BOARD_REVISION} ...)"
+      " given without BOARD argument, please specify BOARD"
+    )
+  endif()
+
+  set(${outvar} ${BUILD_STR_BOARD})
+
+  if(DEFINED BUILD_STR_BOARD_REVISION)
+    string(REPLACE "." "_" revision_string ${BUILD_STR_BOARD_REVISION})
+    set(${outvar} "${${outvar}}_${revision_string}")
+  endif()
+
+  if(BUILD_STR_BUILD)
+    set(${outvar} "${${outvar}}_${BUILD_STR_BUILD}")
+  endif()
+
+  # This updates the provided outvar in parent scope (callers scope)
+  set(${outvar} ${${outvar}} PARENT_SCOPE)
+endfunction()
+
 ########################################################
 # 2. Kconfig-aware extensions
 ########################################################
@@ -2075,6 +2135,8 @@ endfunction()
 #                          Issue an error for any relative path not specified
 #                          by user with `-D<path>`
 #
+# returns an updated list of absolute paths
+#
 # CONF_FILES <path>: Find all configuration files in path and return them in a
 #                    list. Configuration files will be:
 #                    - DTS:       Overlay files (.overlay)
@@ -2096,7 +2158,6 @@ endfunction()
 #                                  BUILD debug, will look for <board>_debug.conf
 #                                  and <board>_debug.overlay, instead of <board>.conf
 #
-# returns an updated list of absolute paths
 function(zephyr_file)
   set(file_options APPLICATION_ROOT CONF_FILES)
   if((ARGC EQUAL 0) OR (NOT (ARGV0 IN_LIST file_options)))
@@ -2112,7 +2173,7 @@ Please provide one of following: APPLICATION_ROOT, CONF_FILES")
 
   cmake_parse_arguments(FILE "" "${single_args}" "" ${ARGN})
   if(FILE_UNPARSED_ARGUMENTS)
-      message(FATAL_ERROR "zephyr_file(${ARGV0} <path> ...) given unknown arguments: ${FILE_UNPARSED_ARGUMENTS}")
+      message(FATAL_ERROR "zephyr_file(${ARGV0} <val> ...) given unknown arguments: ${FILE_UNPARSED_ARGUMENTS}")
   endif()
 
 
@@ -2167,15 +2228,22 @@ Relative paths are only allowed with `-D${ARGV1}=<path>`")
       endif()
     endif()
 
-    set(FILENAMES ${FILE_BOARD})
+    zephyr_build_string(filename
+                        BOARD ${FILE_BOARD}
+                        BUILD ${FILE_BUILD}
+    )
+    set(filename_list ${filename})
 
-    if(DEFINED FILE_BOARD_REVISION)
-      string(REPLACE "." "_" revision_string ${FILE_BOARD_REVISION})
-      list(APPEND FILENAMES "${FILE_BOARD}_${revision_string}")
-    endif()
+    zephyr_build_string(filename
+                        BOARD ${FILE_BOARD}
+                        BOARD_REVISION ${FILE_BOARD_REVISION}
+                        BUILD ${FILE_BUILD}
+    )
+    list(APPEND filename_list ${filename})
+    list(REMOVE_DUPLICATES filename_list)
 
     if(FILE_DTS)
-      foreach(filename ${FILENAMES})
+      foreach(filename ${filename_list})
         if(EXISTS ${FILE_CONF_FILES}/${filename}.overlay)
           list(APPEND ${FILE_DTS} ${FILE_CONF_FILES}/${filename}.overlay)
         endif()
@@ -2186,11 +2254,7 @@ Relative paths are only allowed with `-D${ARGV1}=<path>`")
     endif()
 
     if(FILE_KCONF)
-      foreach(filename ${FILENAMES})
-        if(FILE_BUILD)
-          set(filename "${filename}_${FILE_BUILD}")
-        endif()
-
+      foreach(filename ${filename_list})
         if(EXISTS ${FILE_CONF_FILES}/${filename}.conf)
           list(APPEND ${FILE_KCONF} ${FILE_CONF_FILES}/${filename}.conf)
         endif()