diff --git a/docs/maintainers/vcpkg_common_definitions.md b/docs/maintainers/vcpkg_common_definitions.md
index a97723c1b06..44b7ea74f36 100644
--- a/docs/maintainers/vcpkg_common_definitions.md
+++ b/docs/maintainers/vcpkg_common_definitions.md
@@ -23,6 +23,7 @@ TARGET_TRIPLET                           the name of the current triplet to buil
 CURRENT_INSTALLED_DIR                    the absolute path to the installed files for the current triplet
 HOST_TRIPLET                             the name of the triplet corresponding to the host
 CURRENT_HOST_INSTALLED_DIR               the absolute path to the installed files for the host triplet
+VCPKG_CROSSCOMPILING                     Whether vcpkg is cross-compiling: in other words, whether TARGET_TRIPLET and HOST_TRIPLET are different
 ```
 
 CMAKE_STATIC_LIBRARY_(PREFIX|SUFFIX), CMAKE_SHARED_LIBRARY_(PREFIX|SUFFIX) and CMAKE_IMPORT_LIBRARY_(PREFIX|SUFFIX) are defined for the target
diff --git a/scripts/cmake/vcpkg_common_definitions.cmake b/scripts/cmake/vcpkg_common_definitions.cmake
index b505f3693bb..6d2b6df5b5e 100644
--- a/scripts/cmake/vcpkg_common_definitions.cmake
+++ b/scripts/cmake/vcpkg_common_definitions.cmake
@@ -22,6 +22,7 @@ TARGET_TRIPLET                           the name of the current triplet to buil
 CURRENT_INSTALLED_DIR                    the absolute path to the installed files for the current triplet
 HOST_TRIPLET                             the name of the triplet corresponding to the host
 CURRENT_HOST_INSTALLED_DIR               the absolute path to the installed files for the host triplet
+VCPKG_CROSSCOMPILING                     Whether vcpkg is cross-compiling: in other words, whether TARGET_TRIPLET and HOST_TRIPLET are different
 ```
 
 CMAKE_STATIC_LIBRARY_(PREFIX|SUFFIX), CMAKE_SHARED_LIBRARY_(PREFIX|SUFFIX) and CMAKE_IMPORT_LIBRARY_(PREFIX|SUFFIX) are defined for the target
@@ -29,6 +30,7 @@ Furthermore the variables CMAKE_FIND_LIBRARY_(PREFIXES|SUFFIXES) are also define
 portfiles are able to use find_library calls to discover dependent libraries within the current triplet for ports.
 #]===]
 
+string(COMPARE EQUAL "${TARGET_TRIPLET}" "${HOST_TRIPLET}" VCPKG_CROSSCOMPILING)
 #Helper variable to identify the Target system. VCPKG_TARGET_IS_<targetname>
 if (NOT DEFINED VCPKG_CMAKE_SYSTEM_NAME OR VCPKG_CMAKE_SYSTEM_NAME STREQUAL "")
     set(VCPKG_TARGET_IS_WINDOWS ON)