diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -703,7 +703,7 @@
 option(LLVM_INCLUDE_EXAMPLES "Generate build targets for the LLVM examples" ON)
 
 if(LLVM_BUILD_EXAMPLES)
-  add_definitions(-DBUILD_EXAMPLES)
+  add_compile_definitions(BUILD_EXAMPLES)
 endif(LLVM_BUILD_EXAMPLES)
 
 option(LLVM_BUILD_TESTS
@@ -1059,8 +1059,8 @@
 # Build with _XOPEN_SOURCE on AIX, as stray macros in _ALL_SOURCE mode tend to
 # break things. In this case we need to enable the large-file API as well.
 if (UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
-          add_definitions("-D_XOPEN_SOURCE=700")
-          add_definitions("-D_LARGE_FILE_API")
+          add_compile_definitions(_XOPEN_SOURCE=700)
+          add_compile_definitions(_LARGE_FILE_API)
 
   # CMake versions less than 3.16 set default linker flags to include -brtl, as
   # well as setting -G when building libraries, so clear them out. Note we only
@@ -1095,14 +1095,14 @@
 
 # Build with _XOPEN_SOURCE on z/OS.
 if (CMAKE_SYSTEM_NAME MATCHES "OS390")
-  add_definitions("-D_XOPEN_SOURCE=600")
-  add_definitions("-D_OPEN_SYS") # Needed for process information.
-  add_definitions("-D_OPEN_SYS_FILE_EXT") # Needed for EBCDIC I/O.
+  add_compile_definitions(_XOPEN_SOURCE=600)
+  add_compile_definitions(_OPEN_SYS) # Needed for process information.
+  add_compile_definitions(_OPEN_SYS_FILE_EXT) # Needed for EBCDIC I/O.
 endif()
 
 # Build with _FILE_OFFSET_BITS=64 on Solaris to match g++ >= 9.
 if (UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
-          add_definitions("-D_FILE_OFFSET_BITS=64")
+          add_compile_definitions(_FILE_OFFSET_BITS=64)
 endif()
 
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -61,13 +61,11 @@
 if( LLVM_ENABLE_ASSERTIONS )
   # MSVC doesn't like _DEBUG on release builds. See PR 4379.
   if( NOT MSVC )
-    add_definitions( -D_DEBUG )
+    add_compile_definitions(_DEBUG)
   endif()
   # On non-Debug builds cmake automatically defines NDEBUG, so we
   # explicitly undefine it:
   if( NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" )
-    # NOTE: use `add_compile_options` rather than `add_definitions` since
-    # `add_definitions` does not support generator expressions.
     add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-UNDEBUG>)
     if (MSVC)
       # Also remove /D NDEBUG to avoid MSVC warnings about conflicting defines.
@@ -86,7 +84,7 @@
 endif()
 
 if(LLVM_ENABLE_EXPENSIVE_CHECKS)
-  add_definitions(-DEXPENSIVE_CHECKS)
+  add_compile_definitions(EXPENSIVE_CHECKS)
 
   # In some libstdc++ versions, std::min_element is not constexpr when
   # _GLIBCXX_DEBUG is enabled.
@@ -99,14 +97,14 @@
       return 0;
     }" CXX_SUPPORTS_GLIBCXX_DEBUG)
   if(CXX_SUPPORTS_GLIBCXX_DEBUG)
-    add_definitions(-D_GLIBCXX_DEBUG)
+    add_compile_definitions(_GLIBCXX_DEBUG)
   else()
-    add_definitions(-D_GLIBCXX_ASSERTIONS)
+    add_compile_definitions(_GLIBCXX_ASSERTIONS)
   endif()
 endif()
 
 if (LLVM_ENABLE_STRICT_FIXED_SIZE_VECTORS)
-  add_definitions(-DSTRICT_FIXED_SIZE_VECTORS)
+  add_compile_definitions(STRICT_FIXED_SIZE_VECTORS)
 endif()
 
 string(TOUPPER "${LLVM_ABI_BREAKING_CHECKS}" uppercase_LLVM_ABI_BREAKING_CHECKS)
@@ -372,7 +370,7 @@
 endif()
 
 if(CMAKE_SIZEOF_VOID_P EQUAL 8 AND MINGW)
-  add_definitions( -D_FILE_OFFSET_BITS=64 )
+  add_compile_definitions(_FILE_OFFSET_BITS=64)
 endif()
 
 if( CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32 )
@@ -386,8 +384,8 @@
     set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -m32")
 
     # FIXME: CMAKE_SIZEOF_VOID_P is still 8
-    add_definitions(-D_LARGEFILE_SOURCE)
-    add_definitions(-D_FILE_OFFSET_BITS=64)
+    add_compile_definitions(_LARGEFILE_SOURCE)
+    add_compile_definitions(_FILE_OFFSET_BITS=64)
   endif( LLVM_BUILD_32_BITS )
 endif( CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32 )
 
@@ -399,8 +397,8 @@
 endif()
 if( CMAKE_SIZEOF_VOID_P EQUAL 4 AND NOT LLVM_FORCE_SMALLFILE_FOR_ANDROID)
   # FIXME: It isn't handled in LLVM_BUILD_32_BITS.
-  add_definitions( -D_LARGEFILE_SOURCE )
-  add_definitions( -D_FILE_OFFSET_BITS=64 )
+  add_compile_definitions(_LARGEFILE_SOURCE)
+  add_compile_definitions(_FILE_OFFSET_BITS=64)
 endif()
 
 if( XCODE )
@@ -433,10 +431,10 @@
     "Number of parallel compiler jobs. 0 means use all processors. Default is 0.")
   if( NOT LLVM_COMPILER_JOBS STREQUAL "1" )
     if( LLVM_COMPILER_JOBS STREQUAL "0" )
-      add_definitions( /MP )
+      add_compile_options(/MP)
     else()
       message(STATUS "Number of parallel compiler jobs set to " ${LLVM_COMPILER_JOBS})
-      add_definitions( /MP${LLVM_COMPILER_JOBS} )
+      add_compile_options(/MP${LLVM_COMPILER_JOBS})
     endif()
   else()
     message(STATUS "Parallel compilation disabled")
@@ -465,20 +463,20 @@
   include(ChooseMSVCCRT)
 
   # Add definitions that make MSVC much less annoying.
-  add_definitions(
+  add_compile_definitions(
     # For some reason MS wants to deprecate a bunch of standard functions...
-    -D_CRT_SECURE_NO_DEPRECATE
-    -D_CRT_SECURE_NO_WARNINGS
-    -D_CRT_NONSTDC_NO_DEPRECATE
-    -D_CRT_NONSTDC_NO_WARNINGS
-    -D_SCL_SECURE_NO_DEPRECATE
-    -D_SCL_SECURE_NO_WARNINGS
+    _CRT_SECURE_NO_DEPRECATE
+    _CRT_SECURE_NO_WARNINGS
+    _CRT_NONSTDC_NO_DEPRECATE
+    _CRT_NONSTDC_NO_WARNINGS
+    _SCL_SECURE_NO_DEPRECATE
+    _SCL_SECURE_NO_WARNINGS
     )
 
   # Tell MSVC to use the Unicode version of the Win32 APIs instead of ANSI.
-  add_definitions(
-    -DUNICODE
-    -D_UNICODE
+  add_compile_definitions(
+    UNICODE
+    _UNICODE
   )
 
   if (LLVM_WINSYSROOT)
@@ -963,9 +961,9 @@
   endif()
 endif()
 
-add_definitions( -D__STDC_CONSTANT_MACROS )
-add_definitions( -D__STDC_FORMAT_MACROS )
-add_definitions( -D__STDC_LIMIT_MACROS )
+add_compile_definitions(__STDC_CONSTANT_MACROS)
+add_compile_definitions(__STDC_FORMAT_MACROS)
+add_compile_definitions(__STDC_LIMIT_MACROS)
 
 # clang and gcc don't default-print colored diagnostics when invoked from Ninja.
 if (UNIX AND
diff --git a/llvm/cmake/modules/TensorFlowCompile.cmake b/llvm/cmake/modules/TensorFlowCompile.cmake
--- a/llvm/cmake/modules/TensorFlowCompile.cmake
+++ b/llvm/cmake/modules/TensorFlowCompile.cmake
@@ -114,5 +114,5 @@
   set(GeneratedMLSources ${GeneratedMLSources} ${GENERATED_OBJS} ${GENERATED_HEADERS} PARENT_SCOPE)
   set(MLDeps ${MLDeps} tf_xla_runtime PARENT_SCOPE)
   set(MLLinkDeps ${MLLinkDeps} tf_xla_runtime PARENT_SCOPE)
-  add_definitions(-DLLVM_HAVE_TF_AOT_${fname_allcaps})
+  add_compile_definitions(LLVM_HAVE_TF_AOT_${fname_allcaps})
 endfunction()
diff --git a/llvm/lib/Support/BLAKE3/CMakeLists.txt b/llvm/lib/Support/BLAKE3/CMakeLists.txt
--- a/llvm/lib/Support/BLAKE3/CMakeLists.txt
+++ b/llvm/lib/Support/BLAKE3/CMakeLists.txt
@@ -12,7 +12,7 @@
 endif()
 
 macro(disable_blake3_x86_simd)
-  add_definitions(-DBLAKE3_NO_AVX512 -DBLAKE3_NO_AVX2 -DBLAKE3_NO_SSE41 -DBLAKE3_NO_SSE2)
+  add_compile_definitions(BLAKE3_NO_AVX512 BLAKE3_NO_AVX2 BLAKE3_NO_SSE41 BLAKE3_NO_SSE2)
 endmacro()
 
 # The BLAKE3 team recommends using the assembly versions, from the README:
diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -71,7 +71,7 @@
     set(system_libs ${system_libs} zircon)
   endif()
   if ( HAIKU )
-    add_definitions(-D_BSD_SOURCE)
+    add_compile_definitions(_BSD_SOURCE)
     set(system_libs ${system_libs} bsd)
   endif()
 endif( MSVC OR MINGW )
@@ -100,7 +100,7 @@
   endif()
 
   if(LLVM_INTEGRATED_CRT_ALLOC MATCHES "rpmalloc$")
-    add_definitions(-DENABLE_OVERRIDE -DENABLE_PRELOAD)
+    add_compile_definitions(ENABLE_OVERRIDE ENABLE_PRELOAD)
     set(ALLOCATOR_FILES "${LLVM_INTEGRATED_CRT_ALLOC}/rpmalloc/rpmalloc.c")
   elseif(LLVM_INTEGRATED_CRT_ALLOC MATCHES "snmalloc$")
     set(ALLOCATOR_FILES "${LLVM_INTEGRATED_CRT_ALLOC}/src/snmalloc/override/new.cc")
@@ -322,7 +322,7 @@
 if(LLVM_INTEGRATED_CRT_ALLOC)
   if(LLVM_INTEGRATED_CRT_ALLOC MATCHES "snmalloc$")
     set_property(TARGET LLVMSupport PROPERTY CXX_STANDARD 17)
-    add_definitions(-D_SILENCE_CXX17_ITERATOR_BASE_CLASS_DEPRECATION_WARNING)
+    add_compile_definitions(_SILENCE_CXX17_ITERATOR_BASE_CLASS_DEPRECATION_WARNING)
     if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" AND
         "${CMAKE_SYSTEM_PROCESSOR}" MATCHES "x86_64")
       set_property(TARGET LLVMSupport PROPERTY COMPILE_FLAGS "-mcx16")
diff --git a/llvm/tools/llvm-config/CMakeLists.txt b/llvm/tools/llvm-config/CMakeLists.txt
--- a/llvm/tools/llvm-config/CMakeLists.txt
+++ b/llvm/tools/llvm-config/CMakeLists.txt
@@ -80,7 +80,7 @@
 configure_file(${BUILDVARIABLES_SRCPATH} ${BUILDVARIABLES_OBJPATH} @ONLY)
 
 # Set build-time environment(s).
-add_definitions(-DCMAKE_CFG_INTDIR="${CMAKE_CFG_INTDIR}")
+add_compile_definitions(CMAKE_CFG_INTDIR="${CMAKE_CFG_INTDIR}")
 
 if(LLVM_ENABLE_MODULES)
   target_compile_options(llvm-config PUBLIC