diff --git a/bolt/CMakeLists.txt b/bolt/CMakeLists.txt
--- a/bolt/CMakeLists.txt
+++ b/bolt/CMakeLists.txt
@@ -4,11 +4,35 @@
 set(BOLT_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
 set(CMAKE_CXX_STANDARD 17)
 
+# Determine default set of targets to build -- the intersection of
+# those BOLT supports and those LLVM is targeting.
+set(BOLT_TARGETS_TO_BUILD_all "AArch64;X86")
+set(BOLT_TARGETS_TO_BUILD_default)
+foreach (tgt ${BOLT_TARGETS_TO_BUILD_all})
+  if (tgt IN_LIST LLVM_TARGETS_TO_BUILD)
+    list(APPEND BOLT_TARGETS_TO_BUILD_default ${tgt})
+  endif()
+endforeach()
+
+# Allow the user to specify the BOLT targets, and then check that LLVM
+# is indeed targeting those.
+set(BOLT_TARGETS_TO_BUILD "${BOLT_TARGETS_TO_BUILD_default}"
+  CACHE STRING "Targets for BOLT to support.")
+if (NOT BOLT_TARGETS_TO_BUILD)
+  message(FATAL_ERROR "BOLT enabled but BOLT_TARGETS_TO_BUILD is empty")
+endif()
+foreach (tgt ${BOLT_TARGETS_TO_BUILD})
+  if (NOT tgt IN_LIST LLVM_TARGETS_TO_BUILD)
+    message(FATAL_ERROR "BOLT target '${tgt}' is not in LLVM_TARGETS_TO_BUILD")
+  endif()
+  message(STATUS "Targeting ${tgt} in llvm-bolt")
+endforeach()
+
 set(BOLT_ENABLE_RUNTIME_default OFF)
 if (CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64"
     AND (CMAKE_SYSTEM_NAME STREQUAL "Linux"
       OR CMAKE_SYSTEM_NAME STREQUAL "Darwin")
-    AND "X86" IN_LIST LLVM_TARGETS_TO_BUILD)
+    AND "X86" IN_LIST BOLT_TARGETS_TO_BUILD)
   set(BOLT_ENABLE_RUNTIME_default ON)
 endif()
 option(BOLT_ENABLE_RUNTIME "Enable BOLT runtime" ${BOLT_ENABLE_RUNTIME_default})
diff --git a/bolt/lib/Rewrite/CMakeLists.txt b/bolt/lib/Rewrite/CMakeLists.txt
--- a/bolt/lib/Rewrite/CMakeLists.txt
+++ b/bolt/lib/Rewrite/CMakeLists.txt
@@ -8,24 +8,6 @@
   TargetParser
   )
 
-set(TARGET_LINK_LIBRARIES
-  LLVMBOLTCore
-  LLVMBOLTPasses
-  LLVMBOLTProfile
-  LLVMBOLTRuntimeLibs
-  LLVMBOLTUtils
-  )
-
-if ("AArch64" IN_LIST LLVM_TARGETS_TO_BUILD)
-  list(APPEND TARGET_LINK_LIBRARIES LLVMBOLTTargetAArch64)
-  set(BOLT_AArch64 On)
-endif()
-
-if ("X86" IN_LIST LLVM_TARGETS_TO_BUILD)
-  list(APPEND TARGET_LINK_LIBRARIES LLVMBOLTTargetX86)
-  set(BOLT_X64 On)
-endif()
-
 add_llvm_library(LLVMBOLTRewrite
   BinaryPassManager.cpp
   BoltDiff.cpp
@@ -42,13 +24,15 @@
 
 target_link_libraries(LLVMBOLTRewrite
   PRIVATE
-  ${TARGET_LINK_LIBRARIES}
+  LLVMBOLTCore
+  LLVMBOLTPasses
+  LLVMBOLTProfile
+  LLVMBOLTRuntimeLibs
+  LLVMBOLTUtils
   )
 
-if (DEFINED BOLT_AArch64)
-  target_compile_definitions(LLVMBOLTRewrite PRIVATE AARCH64_AVAILABLE)
-endif()
-
-if (DEFINED BOLT_X64)
-  target_compile_definitions(LLVMBOLTRewrite PRIVATE X86_AVAILABLE)
-endif()
+foreach (tgt ${BOLT_TARGETS_TO_BUILD})
+  target_link_libraries(LLVMBOLTRewrite PRIVATE LLVMBOLTTarget${tgt})
+  string(TOUPPER "${tgt}" upper)
+  target_compile_definitions(LLVMBOLTRewrite PRIVATE ${upper}_AVAILABLE)
+endforeach()
diff --git a/bolt/lib/Target/CMakeLists.txt b/bolt/lib/Target/CMakeLists.txt
--- a/bolt/lib/Target/CMakeLists.txt
+++ b/bolt/lib/Target/CMakeLists.txt
@@ -1,9 +1,3 @@
-if ("X86" IN_LIST LLVM_TARGETS_TO_BUILD)
-  message(STATUS "Targeting X86 in llvm-bolt")
-  add_subdirectory(X86)
-endif()
-
-if ("AArch64" IN_LIST LLVM_TARGETS_TO_BUILD)
-  message(STATUS "Targeting AArch64 in llvm-bolt")
-  add_subdirectory(AArch64)
-endif()
+foreach (tgt ${BOLT_TARGETS_TO_BUILD})
+  add_subdirectory(${tgt})
+endforeach()
diff --git a/bolt/test/lit.site.cfg.py.in b/bolt/test/lit.site.cfg.py.in
--- a/bolt/test/lit.site.cfg.py.in
+++ b/bolt/test/lit.site.cfg.py.in
@@ -17,7 +17,7 @@
 config.python_executable = "@Python3_EXECUTABLE@"
 config.bolt_clang = "@BOLT_CLANG_EXE@"
 config.bolt_lld = "@BOLT_LLD_EXE@"
-config.targets_to_build = "@TARGETS_TO_BUILD@"
+config.targets_to_build = "@BOLT_TARGETS_TO_BUILD@"
 config.gnu_ld = "@GNU_LD_EXECUTABLE@"
 
 import lit.llvm
diff --git a/bolt/unittests/Core/CMakeLists.txt b/bolt/unittests/Core/CMakeLists.txt
--- a/bolt/unittests/Core/CMakeLists.txt
+++ b/bolt/unittests/Core/CMakeLists.txt
@@ -19,20 +19,11 @@
   LLVMBOLTRewrite
   )
 
-if ("AArch64" IN_LIST LLVM_TARGETS_TO_BUILD)
+foreach (tgt ${BOLT_TARGETS_TO_BUILD})
   include_directories(
-    ${LLVM_MAIN_SRC_DIR}/lib/Target/AArch64
-    ${LLVM_BINARY_DIR}/lib/Target/AArch64
+    ${LLVM_MAIN_SRC_DIR}/lib/Target/${tgt}
+    ${LLVM_BINARY_DIR}/lib/Target/${tgt}
   )
-
-  target_compile_definitions(CoreTests PRIVATE AARCH64_AVAILABLE)
-endif()
-
-if ("X86" IN_LIST LLVM_TARGETS_TO_BUILD)
-  include_directories(
-    ${LLVM_MAIN_SRC_DIR}/lib/Target/X86
-    ${LLVM_BINARY_DIR}/lib/Target/X86
-  )
-
-  target_compile_definitions(CoreTests PRIVATE X86_AVAILABLE)
-endif()
+  string(TOUPPER "${tgt}" upper)
+  target_compile_definitions(CoreTests PRIVATE "${upper}_AVAILABLE")
+endforeach()