Revert "[CMake] Simplify CMake handling for zlib"

This reverts commit ccbc1485b55ff4acd21bcfafbf7aec4ed0fd818d which
is still failing on the Windows MLIR bots.

22 files changed, 92 insertions, 76 deletions

diff --git a/clang/test/CMakeLists.txt b/clang/test/CMakeLists.txt
index 334a904..38bbc5b 100644
--- a/clang/test/CMakeLists.txt
+++ b/clang/test/CMakeLists.txt
@@ -9,6 +9,15 @@ endif ()
 
 string(REPLACE ${CMAKE_CFG_INTDIR} ${LLVM_BUILD_MODE} CLANG_TOOLS_DIR ${LLVM_RUNTIME_OUTPUT_INTDIR})
 
+if(CLANG_BUILT_STANDALONE)
+  # Set HAVE_LIBZ according to recorded LLVM_ENABLE_ZLIB value. This
+  # value is forced to 0 if zlib was not found, so it is fine to use it
+  # instead of HAVE_LIBZ (not recorded).
+  if(LLVM_ENABLE_ZLIB)
+    set(HAVE_LIBZ 1)
+  endif()
+endif()
+
 llvm_canonicalize_cmake_booleans(
   CLANG_BUILD_EXAMPLES
   CLANG_ENABLE_ARCMT
@@ -16,7 +25,7 @@ llvm_canonicalize_cmake_booleans(
   CLANG_SPAWN_CC1
   ENABLE_BACKTRACES
   ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER
-  LLVM_ENABLE_ZLIB
+  HAVE_LIBZ
   LLVM_ENABLE_PER_TARGET_RUNTIME_DIR
   LLVM_ENABLE_PLUGINS
   LLVM_ENABLE_THREADS)
diff --git a/clang/test/lit.site.cfg.py.in b/clang/test/lit.site.cfg.py.in
index 286ea06..d9b5b2f 100644
--- a/clang/test/lit.site.cfg.py.in
+++ b/clang/test/lit.site.cfg.py.in
@@ -16,7 +16,7 @@ config.host_triple = "@LLVM_HOST_TRIPLE@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.host_cxx = "@CMAKE_CXX_COMPILER@"
 config.llvm_use_sanitizer = "@LLVM_USE_SANITIZER@"
-config.have_zlib = @LLVM_ENABLE_ZLIB@
+config.have_zlib = @HAVE_LIBZ@
 config.clang_arcmt = @CLANG_ENABLE_ARCMT@
 config.clang_default_cxx_stdlib = "@CLANG_DEFAULT_CXX_STDLIB@"
 config.clang_staticanalyzer = @CLANG_ENABLE_STATIC_ANALYZER@
diff --git a/compiler-rt/test/lit.common.configured.in b/compiler-rt/test/lit.common.configured.in
index 000bf9b..1f746c0 100644
--- a/compiler-rt/test/lit.common.configured.in
+++ b/compiler-rt/test/lit.common.configured.in
@@ -57,7 +57,7 @@ elif config.android:
 else:
   set_default("target_suffix", "-%s" % config.target_arch)
 
-set_default("have_zlib", "@LLVM_ENABLE_ZLIB@")
+set_default("have_zlib", "@HAVE_LIBZ@")
 set_default("libcxx_used", "@LLVM_LIBCXX_USED@")
 
 # LLVM tools dir can be passed in lit parameters, so try to
diff --git a/lld/test/CMakeLists.txt b/lld/test/CMakeLists.txt
index 52e6118..74b29f5 100644
--- a/lld/test/CMakeLists.txt
+++ b/lld/test/CMakeLists.txt
@@ -4,8 +4,17 @@ set(LLVM_BUILD_MODE "%(build_mode)s")
 set(LLVM_TOOLS_DIR "${LLVM_TOOLS_BINARY_DIR}/%(build_config)s")
 set(LLVM_LIBS_DIR "${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/%(build_config)s")
 
+if(LLD_BUILT_STANDALONE)
+  # Set HAVE_LIBZ according to recorded LLVM_ENABLE_ZLIB value. This
+  # value is forced to 0 if zlib was not found, so it is fine to use it
+  # instead of HAVE_LIBZ (not recorded).
+  if(LLVM_ENABLE_ZLIB)
+    set(HAVE_LIBZ 1)
+  endif()
+endif()
+
 llvm_canonicalize_cmake_booleans(
-  LLVM_ENABLE_ZLIB
+  HAVE_LIBZ
   LLVM_LIBXML2_ENABLED
   )
 
diff --git a/lld/test/lit.site.cfg.py.in b/lld/test/lit.site.cfg.py.in
index 3d4c51f..4aa2fcd 100644
--- a/lld/test/lit.site.cfg.py.in
+++ b/lld/test/lit.site.cfg.py.in
@@ -14,7 +14,7 @@ config.lld_libs_dir = "@LLVM_LIBRARY_OUTPUT_INTDIR@"
 config.lld_tools_dir = "@LLVM_RUNTIME_OUTPUT_INTDIR@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.python_executable = "@Python3_EXECUTABLE@"
-config.have_zlib = @LLVM_ENABLE_ZLIB@
+config.have_zlib = @HAVE_LIBZ@
 config.sizeof_void_p = @CMAKE_SIZEOF_VOID_P@
 
 # Support substitution of the tools and libs dirs with user parameters. This is
diff --git a/lldb/cmake/modules/LLDBStandalone.cmake b/lldb/cmake/modules/LLDBStandalone.cmake
index 94781c3..edd2b34 100644
--- a/lldb/cmake/modules/LLDBStandalone.cmake
+++ b/lldb/cmake/modules/LLDBStandalone.cmake
@@ -74,6 +74,10 @@ endif()
 # CMake modules to be in that directory as well.
 list(APPEND CMAKE_MODULE_PATH "${LLVM_DIR}")
 
+if(LLVM_ENABLE_ZLIB)
+  find_package(ZLIB)
+endif()
+
 include(AddLLVM)
 include(TableGen)
 include(HandleLLVMOptions)
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
index 832760f..71522d6 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
@@ -50,7 +50,7 @@
 #include <compression.h>
 #endif
 
-#if LLVM_ENABLE_ZLIB
+#if defined(HAVE_LIBZ)
 #include <zlib.h>
 #endif
 
@@ -582,7 +582,7 @@ bool GDBRemoteCommunication::DecompressPacket() {
   }
 #endif
 
-#if LLVM_ENABLE_ZLIB
+#if defined(HAVE_LIBZ)
   if (decompressed_bytes == 0 && decompressed_bufsize != ULONG_MAX &&
       decompressed_buffer != nullptr &&
       m_compression_type == CompressionType::ZlibDeflate) {
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
index d77f7a0..c75d5e1 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
@@ -1053,7 +1053,7 @@ void GDBRemoteCommunicationClient::MaybeEnableCompression(
   }
 #endif
 
-#if LLVM_ENABLE_ZLIB
+#if defined(HAVE_LIBZ)
   if (avail_type == CompressionType::None) {
     for (auto compression : supported_compressions) {
       if (compression == "zlib-deflate") {
diff --git a/llvm/cmake/config-ix.cmake b/llvm/cmake/config-ix.cmake
index 2533093..90e5d32 100644
--- a/llvm/cmake/config-ix.cmake
+++ b/llvm/cmake/config-ix.cmake
@@ -56,6 +56,7 @@ check_include_file(sys/types.h HAVE_SYS_TYPES_H)
 check_include_file(termios.h HAVE_TERMIOS_H)
 check_include_file(unistd.h HAVE_UNISTD_H)
 check_include_file(valgrind/valgrind.h HAVE_VALGRIND_VALGRIND_H)
+check_include_file(zlib.h HAVE_ZLIB_H)
 check_include_file(fenv.h HAVE_FENV_H)
 check_symbol_exists(FE_ALL_EXCEPT "fenv.h" HAVE_DECL_FE_ALL_EXCEPT)
 check_symbol_exists(FE_INEXACT "fenv.h" HAVE_DECL_FE_INEXACT)
@@ -114,28 +115,22 @@ if(HAVE_LIBPTHREAD)
   set(LLVM_PTHREAD_LIB ${CMAKE_THREAD_LIBS_INIT})
 endif()
 
-if(LLVM_ENABLE_ZLIB)
-  if(LLVM_ENABLE_ZLIB STREQUAL FORCE_ON)
-    find_package(ZLIB REQUIRED)
-  elseif(NOT LLVM_USE_SANITIZER MATCHES "Memory.*")
-    find_package(ZLIB)
-  else()
-    set(ZLIB_FOUND FALSE)
-  endif()
-  if(ZLIB_FOUND)
-    # Check if zlib we found is usable; for example, we may have found a 32-bit
-    # library on a 64-bit system which would result in a link-time failure.
-    check_library_exists(${ZLIB_LIBRARY} compress2 "" ZLIB_FOUND)
-    if(LLVM_ENABLE_ZLIB STREQUAL FORCE_ON AND NOT ZLIB_FOUND)
-      message(FATAL_ERROR "${ZLIB_LIBRARY} cannot be used")
-    endif()
-  endif()
-  set(LLVM_ENABLE_ZLIB "${ZLIB_FOUND}")
-endif()
-
 # Don't look for these libraries if we're using MSan, since uninstrumented third
 # party code may call MSan interceptors like strlen, leading to false positives.
 if(NOT LLVM_USE_SANITIZER MATCHES "Memory.*")
+  set(HAVE_LIBZ 0)
+  if(LLVM_ENABLE_ZLIB)
+    foreach(library z zlib_static zlib)
+      string(TOUPPER ${library} library_suffix)
+      check_library_exists(${library} compress2 "" HAVE_LIBZ_${library_suffix})
+      if(HAVE_LIBZ_${library_suffix})
+        set(HAVE_LIBZ 1)
+        set(ZLIB_LIBRARIES "${library}")
+        break()
+      endif()
+    endforeach()
+  endif()
+
   # Don't look for these libraries on Windows.
   if (NOT PURE_WINDOWS)
     # Skip libedit if using ASan as it contains memory leaks.
@@ -180,6 +175,10 @@ if (LLVM_ENABLE_LIBXML2 STREQUAL "FORCE_ON" AND NOT LLVM_LIBXML2_ENABLED)
   message(FATAL_ERROR "Failed to congifure libxml2")
 endif()
 
+if (LLVM_ENABLE_ZLIB STREQUAL "FORCE_ON" AND NOT HAVE_LIBZ)
+  message(FATAL_ERROR "Failed to configure zlib")
+endif()
+
 check_library_exists(xar xar_open "" HAVE_LIBXAR)
 if(HAVE_LIBXAR)
   set(XAR_LIB xar)
@@ -518,6 +517,13 @@ else( LLVM_ENABLE_THREADS )
   message(STATUS "Threads disabled.")
 endif()
 
+if (LLVM_ENABLE_ZLIB )
+  # Check if zlib is available in the system.
+  if ( NOT HAVE_ZLIB_H OR NOT HAVE_LIBZ )
+    set(LLVM_ENABLE_ZLIB 0)
+  endif()
+endif()
+
 if (LLVM_ENABLE_DOXYGEN)
   message(STATUS "Doxygen enabled.")
   find_package(Doxygen REQUIRED)
diff --git a/llvm/cmake/modules/LLVMConfig.cmake.in b/llvm/cmake/modules/LLVMConfig.cmake.in
index a5c370b..4d8e337 100644
--- a/llvm/cmake/modules/LLVMConfig.cmake.in
+++ b/llvm/cmake/modules/LLVMConfig.cmake.in
@@ -51,9 +51,6 @@ set(LLVM_ENABLE_THREADS @LLVM_ENABLE_THREADS@)
 set(LLVM_ENABLE_UNWIND_TABLES @LLVM_ENABLE_UNWIND_TABLES@)
 
 set(LLVM_ENABLE_ZLIB @LLVM_ENABLE_ZLIB@)
-if(LLVM_ENABLE_ZLIB)
-  find_package(ZLIB)
-endif()
 
 set(LLVM_LIBXML2_ENABLED @LLVM_LIBXML2_ENABLED@)
 
diff --git a/llvm/include/llvm/Config/config.h.cmake b/llvm/include/llvm/Config/config.h.cmake
index b8c7e07..70543be 100644
--- a/llvm/include/llvm/Config/config.h.cmake
+++ b/llvm/include/llvm/Config/config.h.cmake
@@ -115,6 +115,9 @@
 /* Define to 1 if you have the `pthread_setname_np' function. */
 #cmakedefine HAVE_PTHREAD_SETNAME_NP ${HAVE_PTHREAD_SETNAME_NP}
 
+/* Define to 1 if you have the `z' library (-lz). */
+#cmakedefine HAVE_LIBZ ${HAVE_LIBZ}
+
 /* Define to 1 if you have the <link.h> header file. */
 #cmakedefine HAVE_LINK_H ${HAVE_LINK_H}
 
@@ -223,6 +226,9 @@
 /* Define to 1 if you have the <valgrind/valgrind.h> header file. */
 #cmakedefine HAVE_VALGRIND_VALGRIND_H ${HAVE_VALGRIND_VALGRIND_H}
 
+/* Define to 1 if you have the <zlib.h> header file. */
+#cmakedefine HAVE_ZLIB_H ${HAVE_ZLIB_H}
+
 /* Have host's _alloca */
 #cmakedefine HAVE__ALLOCA ${HAVE__ALLOCA}
 
diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index 7b45dc6..17bef02 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -1,7 +1,7 @@
-if(LLVM_ENABLE_ZLIB)
-  set(imported_libs ZLIB::ZLIB)
+set(system_libs)
+if ( LLVM_ENABLE_ZLIB AND HAVE_LIBZ )
+  set(system_libs ${system_libs} ${ZLIB_LIBRARIES})
 endif()
-
 if( MSVC OR MINGW )
   # libuuid required for FOLDERID_Profile usage in lib/Support/Windows/Path.inc.
   # advapi32 required for CryptAcquireContextW in lib/Support/Windows/Path.inc.
@@ -194,35 +194,10 @@ add_llvm_component_library(LLVMSupport
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/ADT
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/Support
   ${Backtrace_INCLUDE_DIRS}
-  LINK_LIBS ${system_libs} ${imported_libs} ${delayload_flags} ${Z3_LINK_FILES}
+  LINK_LIBS ${system_libs} ${delayload_flags} ${Z3_LINK_FILES}
   )
 
-set(llvm_system_libs ${system_libs})
-
-if(LLVM_ENABLE_ZLIB)
-  # CMAKE_BUILD_TYPE is only meaningful to single-configuration generators.
-  if(CMAKE_BUILD_TYPE)
-    string(TOUPPER ${CMAKE_BUILD_TYPE} build_type)
-    get_property(zlib_library TARGET ZLIB::ZLIB PROPERTY LOCATION_${build_type})
-  endif()
-  if(NOT zlib_library)
-    get_property(zlib_library TARGET ZLIB::ZLIB PROPERTY LOCATION)
-  endif()
-  get_filename_component(zlib_library ${zlib_library} NAME)
-  if(CMAKE_STATIC_LIBRARY_PREFIX AND CMAKE_STATIC_LIBRARY_SUFFIX AND
-      zlib_library MATCHES "^${CMAKE_STATIC_LIBRARY_PREFIX}.*${CMAKE_STATIC_LIBRARY_SUFFIX}$")
-    STRING(REGEX REPLACE "^${CMAKE_STATIC_LIBRARY_PREFIX}" "" zlib_library ${zlib_library})
-    STRING(REGEX REPLACE "${CMAKE_STATIC_LIBRARY_SUFFIX}$" "" zlib_library ${zlib_library})
-  endif()
-  if(CMAKE_SHARED_LIBRARY_PREFIX AND CMAKE_SHARED_LIBRARY_SUFFIX AND
-      zlib_library MATCHES "^${CMAKE_SHARED_LIBRARY_PREFIX}.*${CMAKE_SHARED_LIBRARY_SUFFIX}$")
-    STRING(REGEX REPLACE "^${CMAKE_SHARED_LIBRARY_PREFIX}" "" zlib_library ${zlib_library})
-    STRING(REGEX REPLACE "${CMAKE_SHARED_LIBRARY_SUFFIX}$" "" zlib_library ${zlib_library})
-  endif()
-  set(llvm_system_libs ${llvm_system_libs} "${zlib_library}")
-endif()
-
-set_property(TARGET LLVMSupport PROPERTY LLVM_SYSTEM_LIBS "${llvm_system_libs}")
+set_property(TARGET LLVMSupport PROPERTY LLVM_SYSTEM_LIBS "${system_libs}")
 
 if(LLVM_WITH_Z3)
   target_include_directories(LLVMSupport SYSTEM
diff --git a/llvm/lib/Support/CRC.cpp b/llvm/lib/Support/CRC.cpp
index 2bc668b..7ff09de 100644
--- a/llvm/lib/Support/CRC.cpp
+++ b/llvm/lib/Support/CRC.cpp
@@ -25,7 +25,7 @@
 
 using namespace llvm;
 
-#if !LLVM_ENABLE_ZLIB
+#if LLVM_ENABLE_ZLIB == 0 || !HAVE_ZLIB_H
 
 static const uint32_t CRCTable[256] = {
     0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
diff --git a/llvm/lib/Support/Compression.cpp b/llvm/lib/Support/Compression.cpp
index b8c77cf..27d92f0 100644
--- a/llvm/lib/Support/Compression.cpp
+++ b/llvm/lib/Support/Compression.cpp
@@ -17,13 +17,13 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
-#if LLVM_ENABLE_ZLIB
+#if LLVM_ENABLE_ZLIB == 1 && HAVE_ZLIB_H
 #include <zlib.h>
 #endif
 
 using namespace llvm;
 
-#if LLVM_ENABLE_ZLIB
+#if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
 static Error createError(StringRef Err) {
   return make_error<StringError>(Err, inconvertibleErrorCode());
 }
diff --git a/llvm/test/CMakeLists.txt b/llvm/test/CMakeLists.txt
index cde8003..a01e278 100644
--- a/llvm/test/CMakeLists.txt
+++ b/llvm/test/CMakeLists.txt
@@ -1,12 +1,12 @@
 llvm_canonicalize_cmake_booleans(
   BUILD_SHARED_LIBS
   HAVE_LIBXAR
+  HAVE_LIBZ
   HAVE_OCAMLOPT
   HAVE_OCAML_OUNIT
   LLVM_ENABLE_DIA_SDK
   LLVM_ENABLE_FFI
   LLVM_ENABLE_THREADS
-  LLVM_ENABLE_ZLIB
   LLVM_INCLUDE_GO_TESTS
   LLVM_LIBXML2_ENABLED
   LLVM_LINK_LLVM_DYLIB
diff --git a/llvm/test/lit.site.cfg.py.in b/llvm/test/lit.site.cfg.py.in
index 52f709f..c04ef04 100644
--- a/llvm/test/lit.site.cfg.py.in
+++ b/llvm/test/lit.site.cfg.py.in
@@ -33,7 +33,7 @@ config.host_cxx = "@HOST_CXX@"
 config.host_ldflags = '@HOST_LDFLAGS@'
 config.llvm_use_intel_jitevents = @LLVM_USE_INTEL_JITEVENTS@
 config.llvm_use_sanitizer = "@LLVM_USE_SANITIZER@"
-config.have_zlib = @LLVM_ENABLE_ZLIB@
+config.have_zlib = @HAVE_LIBZ@
 config.have_libxar = @HAVE_LIBXAR@
 config.have_dia_sdk = @LLVM_ENABLE_DIA_SDK@
 config.enable_ffi = @LLVM_ENABLE_FFI@
diff --git a/llvm/unittests/Support/CompressionTest.cpp b/llvm/unittests/Support/CompressionTest.cpp
index 5172389..cc7be43 100644
--- a/llvm/unittests/Support/CompressionTest.cpp
+++ b/llvm/unittests/Support/CompressionTest.cpp
@@ -21,7 +21,7 @@ using namespace llvm;
 
 namespace {
 
-#if LLVM_ENABLE_ZLIB
+#if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
 
 void TestZlibCompression(StringRef Input, int Level) {
   SmallString<32> Compressed;
diff --git a/llvm/utils/gn/secondary/clang/test/BUILD.gn b/llvm/utils/gn/secondary/clang/test/BUILD.gn
index a0680d9..56feaae 100644
--- a/llvm/utils/gn/secondary/clang/test/BUILD.gn
+++ b/llvm/utils/gn/secondary/clang/test/BUILD.gn
@@ -79,9 +79,9 @@ write_lit_config("lit_site_cfg") {
   }
 
   if (llvm_enable_zlib) {
-    extra_values += [ "LLVM_ENABLE_ZLIB=1" ]
+    extra_values += [ "HAVE_LIBZ=1" ]
   } else {
-    extra_values += [ "LLVM_ENABLE_ZLIB=0" ]  # Must be 0.
+    extra_values += [ "HAVE_LIBZ=0" ]  # Must be 0.
   }
 
   if (host_cpu == "x64") {
diff --git a/llvm/utils/gn/secondary/compiler-rt/test/BUILD.gn b/llvm/utils/gn/secondary/compiler-rt/test/BUILD.gn
index 5f80586..97007ee 100644
--- a/llvm/utils/gn/secondary/compiler-rt/test/BUILD.gn
+++ b/llvm/utils/gn/secondary/compiler-rt/test/BUILD.gn
@@ -86,8 +86,8 @@ write_cmake_config("lit_common_configured") {
   }
 
   if (llvm_enable_zlib) {
-    values += [ "LLVM_ENABLE_ZLIB=1" ]
+    values += [ "HAVE_LIBZ=1" ]
   } else {
-    values += [ "LLVM_ENABLE_ZLIB=0" ]
+    values += [ "HAVE_LIBZ=0" ]
   }
 }
diff --git a/llvm/utils/gn/secondary/lld/test/BUILD.gn b/llvm/utils/gn/secondary/lld/test/BUILD.gn
index bfb63a3..508225b 100644
--- a/llvm/utils/gn/secondary/lld/test/BUILD.gn
+++ b/llvm/utils/gn/secondary/lld/test/BUILD.gn
@@ -49,9 +49,9 @@ write_lit_cfg("lit_site_cfg") {
   }
 
   if (llvm_enable_zlib) {
-    extra_values += [ "LLVM_ENABLE_ZLIB=1" ]
+    extra_values += [ "HAVE_LIBZ=1" ]
   } else {
-    extra_values += [ "LLVM_ENABLE_ZLIB=0" ]  # Must be 0.
+    extra_values += [ "HAVE_LIBZ=0" ]  # Must be 0.
   }
 
   if (current_cpu == "x64" || current_cpu == "arm64" ||
diff --git a/llvm/utils/gn/secondary/llvm/include/llvm/Config/BUILD.gn b/llvm/utils/gn/secondary/llvm/include/llvm/Config/BUILD.gn
index c9e7c45..741729e 100644
--- a/llvm/utils/gn/secondary/llvm/include/llvm/Config/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/include/llvm/Config/BUILD.gn
@@ -295,10 +295,20 @@ write_cmake_config("config") {
     values += [ "LLVM_ENABLE_DIA_SDK=" ]
   }
 
+  # FIXME: Once https://reviews.llvm.org/D79219 is in, remove the two
+  # redundant HAVE_ variables.
   if (llvm_enable_zlib) {
-    values += [ "LLVM_ENABLE_ZLIB=1" ]
+    values += [
+      "HAVE_LIBZ=1",
+      "HAVE_ZLIB_H=1",
+      "LLVM_ENABLE_ZLIB=1",
+    ]
   } else {
-    values += [ "LLVM_ENABLE_ZLIB=" ]
+    values += [
+      "HAVE_LIBZ=",
+      "HAVE_ZLIB_H=",
+      "LLVM_ENABLE_ZLIB=",
+    ]
   }
 
   if (llvm_enable_libxml2) {
diff --git a/llvm/utils/gn/secondary/llvm/test/BUILD.gn b/llvm/utils/gn/secondary/llvm/test/BUILD.gn
index c714d9b..f272bc1 100644
--- a/llvm/utils/gn/secondary/llvm/test/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/test/BUILD.gn
@@ -174,9 +174,9 @@ write_lit_config("lit_site_cfg") {
   }
 
   if (llvm_enable_zlib) {
-    extra_values += [ "LLVM_ENABLE_ZLIB=1" ]
+    extra_values += [ "HAVE_LIBZ=1" ]
   } else {
-    extra_values += [ "LLVM_ENABLE_ZLIB=0" ]  # Must be 0.
+    extra_values += [ "HAVE_LIBZ=0" ]  # Must be 0.
   }
 }