diff --git a/.gitmodules b/.gitmodules
index a83702e82a..53b0f86697 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -19,9 +19,6 @@
 [submodule "auxil/netcontrol-connectors"]
 	path = auxil/netcontrol-connectors
 	url = https://github.com/zeek/zeek-netcontrol
-[submodule "auxil/bifcl"]
-	path = auxil/bifcl
-	url = https://github.com/zeek/bifcl
 [submodule "doc"]
 	path = doc
 	url = https://github.com/zeek/zeek-docs
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d2b4734d54..6e146f1a2c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -904,11 +904,11 @@ set(_binpac_exe_path "included")
 find_package(BinPAC REQUIRED)
 add_executable(Zeek::BinPAC ALIAS binpac)
 
-add_subdirectory(auxil/bifcl)
+add_subdirectory(tools/bifcl)
 add_executable(Zeek::BifCl ALIAS bifcl)
 # FIXME: avoid hard-coding a path for multi-config generator support. See the
 # TODO in ZeekPluginConfig.cmake.in.
-set(BIFCL_EXE_PATH "${CMAKE_BINARY_DIR}/auxil/bifcl/bifcl${CMAKE_EXECUTABLE_SUFFIX}")
+set(BIFCL_EXE_PATH "${CMAKE_BINARY_DIR}/tools/bifcl/bifcl${CMAKE_EXECUTABLE_SUFFIX}")
 set(_bifcl_exe_path "included")
 
 if (NOT GEN_ZAM_EXE_PATH)
diff --git a/auxil/bifcl b/auxil/bifcl
deleted file mode 160000
index 5947749f78..0000000000
--- a/auxil/bifcl
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 5947749f7850b075f11d6a2aaefe7dad4f63cb62
diff --git a/tools/bifcl/CMakeLists.txt b/tools/bifcl/CMakeLists.txt
index e422a962d1..9896236429 100644
--- a/tools/bifcl/CMakeLists.txt
+++ b/tools/bifcl/CMakeLists.txt
@@ -1,70 +1,26 @@
-cmake_minimum_required(VERSION 3.15.0 FATAL_ERROR)
-project(BifCl C CXX)
-
-include(cmake/CommonCMakeConfig.cmake)
-include(cmake/RequireCXXStd.cmake)
-
 find_package(BISON REQUIRED)
 find_package(FLEX REQUIRED)
 
-if (MSVC)
-    add_compile_options(/J) # Similar to -funsigned-char on other platforms
-    set_property(SOURCE bif_lex.cc APPEND_STRING PROPERTY COMPILE_FLAGS "/wd4018")
-else ()
-    set_property(SOURCE bif_lex.cc APPEND_STRING PROPERTY COMPILE_FLAGS "-Wno-sign-compare")
-endif ()
-
-include_directories(BEFORE ${BifCl_SOURCE_DIR}/include ${BifCl_BINARY_DIR})
-
 set(BISON_FLAGS "--debug")
 
 # BIF parser/scanner
-bison_target(BIFParser builtin-func.y ${BifCl_BINARY_DIR}/bif_parse.cc
-             DEFINES_FILE ${BifCl_BINARY_DIR}/bif_parse.h COMPILE_FLAGS "${BISON_FLAGS}")
-flex_target(BIFScanner builtin-func.l ${BifCl_BINARY_DIR}/bif_lex.cc)
+bison_target(BIFParser builtin-func.y ${CMAKE_CURRENT_BINARY_DIR}/bif_parse.cc
+             DEFINES_FILE ${CMAKE_CURRENT_BINARY_DIR}/bif_parse.h COMPILE_FLAGS "${BISON_FLAGS}")
+flex_target(BIFScanner builtin-func.l ${CMAKE_CURRENT_BINARY_DIR}/bif_lex.cc)
 add_flex_bison_dependency(BIFScanner BIFParser)
 
-set(bifcl_SRCS
-    ${BISON_BIFParser_INPUT}
-    ${FLEX_BIFScanner_INPUT}
-    ${BISON_BIFParser_OUTPUTS}
-    ${FLEX_BIFScanner_OUTPUTS}
-    bif_arg.cc
-    include/bif_arg.h
-    module_util.cc
-    include/module_util.h)
+set(bifcl_SRCS ${BISON_BIFParser_INPUT} ${FLEX_BIFScanner_INPUT} ${BISON_BIFParser_OUTPUTS}
+               ${FLEX_BIFScanner_OUTPUTS} bif_arg.cc module_util.cc)
 
 add_executable(bifcl ${bifcl_SRCS})
+target_include_directories(bifcl BEFORE PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include)
 
 if (MSVC)
-    # If building separately from zeek, we need to add the libunistd subdirectory
-    # so that linking doesn't fail.
-    if ("${CMAKE_PROJECT_NAME}" STREQUAL "BifCl")
-        add_subdirectory(auxil/libunistd EXCLUDE_FROM_ALL)
-    endif ()
+    target_compile_options(bifcl PUBLIC "/J") # Similar to -funsigned-char on other platforms
+    target_compile_options(bifcl PUBLIC "/wd4018") # Similar to -Wno-sign-compare on other platforms
     target_link_libraries(bifcl PRIVATE libunistd)
+else ()
+    target_compile_options(bifcl PUBLIC "-Wno-sign-compare")
 endif ()
 
 install(TARGETS bifcl DESTINATION bin)
-
-if (CMAKE_BUILD_TYPE)
-    string(TOUPPER ${CMAKE_BUILD_TYPE} BuildType)
-endif ()
-
-message(
-    "\n====================|  Bifcl Build Summary  |====================="
-    "\n"
-    "\nBuild type:        ${CMAKE_BUILD_TYPE}"
-    "\nBuild dir:         ${PROJECT_BINARY_DIR}"
-    "\nInstall prefix:    ${CMAKE_INSTALL_PREFIX}"
-    "\nDebug mode:        ${ENABLE_DEBUG}"
-    "\n"
-    "\nCC:                ${CMAKE_C_COMPILER}"
-    "\nCFLAGS:            ${CMAKE_C_FLAGS} ${CMAKE_C_FLAGS_${BuildType}}"
-    "\nCXX:               ${CMAKE_CXX_COMPILER}"
-    "\nCXXFLAGS:          ${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_${BuildType}}"
-    "\nCPP:               ${CMAKE_CXX_COMPILER}"
-    "\n"
-    "\n================================================================\n")
-
-include(UserChangedWarning)
diff --git a/tools/bifcl/bif_arg.cc b/tools/bifcl/bif_arg.cc
index 920846e4a8..a75d480b9a 100644
--- a/tools/bifcl/bif_arg.cc
+++ b/tools/bifcl/bif_arg.cc
@@ -1,3 +1,5 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
 #include "bif_arg.h"
 
 #include <cstring>
diff --git a/tools/bifcl/include/bif_arg.h b/tools/bifcl/include/bif_arg.h
index a9febd013b..57e38cbbd6 100644
--- a/tools/bifcl/include/bif_arg.h
+++ b/tools/bifcl/include/bif_arg.h
@@ -1,3 +1,5 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
 #pragma once
 
 #include <cstdint>
diff --git a/tools/bifcl/include/module_util.h b/tools/bifcl/include/module_util.h
index 30015e527c..92a4c7598a 100644
--- a/tools/bifcl/include/module_util.h
+++ b/tools/bifcl/include/module_util.h
@@ -1,3 +1,5 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
 //
 // These functions are used by both Zeek and bifcl.
 //