diff --git a/lib/CompilerSwiftSyntax/CMakeLists.txt b/lib/CompilerSwiftSyntax/CMakeLists.txt
index 06b055fd0474f..52d0dc78775a7 100644
--- a/lib/CompilerSwiftSyntax/CMakeLists.txt
+++ b/lib/CompilerSwiftSyntax/CMakeLists.txt
@@ -8,6 +8,10 @@ endif()
 
 # Build swift-syntax libraries with FetchContent.
 function(includeSwiftSyntax)
+  set(CMAKE_SYSTEM_PROCESSOR ${SWIFT_HOST_VARIANT_ARCH})
+  set(CMAKE_OSX_ARCHITECTURES ${SWIFT_HOST_VARIANT_ARCH})
+  set(CMAKE_C_COMPILER_TARGET ${SWIFT_HOST_TRIPLE})
+  set(CMAKE_CXX_COMPILER_TARGET ${SWIFT_HOST_TRIPLE})
   set(CMAKE_Swift_COMPILER_TARGET ${SWIFT_HOST_TRIPLE})
   set(BUILD_SHARED_LIBS ON)
   set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${SWIFT_HOST_LIBRARIES_DEST_DIR}/compiler")
diff --git a/lib/SwiftSyntax/CMakeLists.txt b/lib/SwiftSyntax/CMakeLists.txt
index e07e01a60fd78..4beb2044689ca 100644
--- a/lib/SwiftSyntax/CMakeLists.txt
+++ b/lib/SwiftSyntax/CMakeLists.txt
@@ -7,6 +7,10 @@ if(NOT EXISTS "${SWIFT_PATH_TO_SWIFT_SYNTAX_SOURCE}")
 endif()
 
 # Build swift-syntax libraries with FetchContent.
+set(CMAKE_SYSTEM_PROCESSOR ${SWIFT_HOST_VARIANT_ARCH})
+set(CMAKE_OSX_ARCHITECTURES ${SWIFT_HOST_VARIANT_ARCH})
+set(CMAKE_C_COMPILER_TARGET ${SWIFT_HOST_TRIPLE})
+set(CMAKE_CXX_COMPILER_TARGET ${SWIFT_HOST_TRIPLE})
 set(CMAKE_Swift_COMPILER_TARGET ${SWIFT_HOST_TRIPLE})
 set(BUILD_SHARED_LIBS ON)
 # All libraries in 'swift-syntax' goes to 'lib/swift/host'.