diff --git a/arch/x86_64/src/cmake/Toolchain.cmake b/arch/x86_64/src/cmake/Toolchain.cmake
index 9ed22f1c0d..08dae29449 100644
--- a/arch/x86_64/src/cmake/Toolchain.cmake
+++ b/arch/x86_64/src/cmake/Toolchain.cmake
@@ -122,6 +122,11 @@ add_compile_options(
   -Wno-unknown-pragmas
   $<$<COMPILE_LANGUAGE:C>:-Wstrict-prototypes>)
 
+# LLVM target definitions
+set(LLVM_ARCH "x86_64")
+set(LLVM_CPU "x86-64")
+set(LLVM_ABI "sysv")
+
 if(CONFIG_CXX_STANDARD)
   add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-std=${CONFIG_CXX_STANDARD}>)
 endif()
diff --git a/arch/x86_64/src/common/Toolchain.defs b/arch/x86_64/src/common/Toolchain.defs
index 5661577374..be3490a122 100644
--- a/arch/x86_64/src/common/Toolchain.defs
+++ b/arch/x86_64/src/common/Toolchain.defs
@@ -70,6 +70,11 @@ ARCHCPUFLAGS = -fno-pic -mcmodel=large -mno-red-zone -mrdrnd
 ARCHPICFLAGS = -fPIC
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 
+# LLVM target definitions
+LLVM_ARCHTYPE := x86_64
+LLVM_CPUTYPE := x86-64
+LLVM_ABITYPE := sysv
+
 # We have to use a cross-development toolchain under Cygwin because the native
 # Cygwin toolchains don't generate ELF binaries.