diff --git a/compat/mingw.c b/compat/mingw.c
index e0fbd2c66de23d..563e6299bc30c2 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -3134,6 +3134,45 @@ int xwcstoutf(char *utf, const wchar_t *wcs, size_t utflen)
 	return -1;
 }
 
+#ifdef ENSURE_MSYSTEM_IS_SET
+#if !defined(RUNTIME_PREFIX) || !defined(HAVE_WPGMPTR) || !defined(MINGW_PREFIX)
+static size_t append_system_bin_dirs(char *path UNUSED, size_t size UNUSED)
+{
+	return 0;
+}
+#else
+static size_t append_system_bin_dirs(char *path, size_t size)
+{
+	char prefix[32768];
+	const char *slash;
+	size_t len = xwcstoutf(prefix, _wpgmptr, sizeof(prefix)), off = 0;
+
+	if (len == 0 || len >= sizeof(prefix) ||
+	    !(slash = find_last_dir_sep(prefix)))
+		return 0;
+	/* strip trailing `git.exe` */
+	len = slash - prefix;
+
+	/* strip trailing `cmd` or `<mingw-prefix>\bin` or `bin` or `libexec\git-core` */
+	if (strip_suffix_mem(prefix, &len, "\\" MINGW_PREFIX "\\libexec\\git-core") ||
+	    strip_suffix_mem(prefix, &len, "\\" MINGW_PREFIX "\\bin"))
+		off += xsnprintf(path + off, size - off,
+				 "%.*s\\" MINGW_PREFIX "\\bin;", (int)len, prefix);
+	else if (strip_suffix_mem(prefix, &len, "\\cmd") ||
+		 strip_suffix_mem(prefix, &len, "\\bin") ||
+		 strip_suffix_mem(prefix, &len, "\\libexec\\git-core"))
+		off += xsnprintf(path + off, size - off,
+				 "%.*s\\" MINGW_PREFIX "\\bin;", (int)len, prefix);
+	else
+		return 0;
+
+	off += xsnprintf(path + off, size - off,
+			 "%.*s\\usr\\bin;", (int)len, prefix);
+	return off;
+}
+#endif
+#endif
+
 static void setup_windows_environment(void)
 {
 	char *tmp = getenv("TMPDIR");
@@ -3185,6 +3224,35 @@ static void setup_windows_environment(void)
 		if (!tmp && (tmp = getenv("USERPROFILE")))
 			setenv("HOME", tmp, 1);
 	}
+
+	if (!getenv("PLINK_PROTOCOL"))
+		setenv("PLINK_PROTOCOL", "ssh", 0);
+
+#ifdef ENSURE_MSYSTEM_IS_SET
+	if (!(tmp = getenv("MSYSTEM")) || !tmp[0]) {
+		const char *home = getenv("HOME"), *path = getenv("PATH");
+		char buf[32768];
+		size_t off = 0;
+
+		setenv("MSYSTEM", ENSURE_MSYSTEM_IS_SET, 1);
+
+		if (home)
+			off += xsnprintf(buf + off, sizeof(buf) - off,
+					 "%s\\bin;", home);
+		off += append_system_bin_dirs(buf + off, sizeof(buf) - off);
+		if (path)
+			off += xsnprintf(buf + off, sizeof(buf) - off,
+					 "%s", path);
+		else if (off > 0)
+			buf[off - 1] = '\0';
+		else
+			buf[0] = '\0';
+		setenv("PATH", buf, 1);
+	}
+#endif
+
+	if (!getenv("LC_ALL") && !getenv("LC_CTYPE") && !getenv("LANG"))
+		setenv("LC_CTYPE", "C.UTF-8", 1);
 }
 
 int mingw_platform_has_symlinks(void)
diff --git a/config.mak.uname b/config.mak.uname
index 9ebd240378ca59..0b63be10b7782e 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -465,14 +465,8 @@ ifeq ($(uname_S),Windows)
 	GIT_VERSION := $(GIT_VERSION).MSVC
 	pathsep = ;
 	# Assume that this is built in Git for Windows' SDK
-        ifeq (MINGW32,$(MSYSTEM))
-		prefix = /mingw32
-        else
-                ifeq (CLANGARM64,$(MSYSTEM))
-			prefix = /clangarm64
-                else
-			prefix = /mingw64
-                endif
+        ifneq (,$(MSYSTEM))
+		prefix = $(MINGW_PREFIX)
         endif
 	# Prepend MSVC 64-bit tool-chain to PATH.
 	#
@@ -524,7 +518,8 @@ ifeq ($(uname_S),Windows)
 	NO_POSIX_GOODIES = UnfortunatelyYes
 	NATIVE_CRLF = YesPlease
 	DEFAULT_HELP_FORMAT = html
-ifeq (/mingw64,$(subst 32,64,$(subst clangarm,mingw,$(prefix))))
+	SKIP_DASHED_BUILT_INS = YabbaDabbaDoo
+ifneq (,$(MINGW_PREFIX))
 	# Move system config into top-level /etc/
 	ETC_GITCONFIG = ../etc/gitconfig
 	ETC_GITATTRIBUTES = ../etc/gitattributes
@@ -540,7 +535,9 @@ endif
 		compat/win32/pthread.o compat/win32/syslog.o \
 		compat/win32/trace2_win32_process_info.o \
 		compat/win32/dirent.o
-	COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DDETECT_MSYS_TTY -DNOGDI -DHAVE_STRING_H -Icompat -Icompat/regex -Icompat/win32 -DSTRIP_EXTENSION=\".exe\"
+	COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DDETECT_MSYS_TTY \
+		-DENSURE_MSYSTEM_IS_SET="\"$(MSYSTEM)\"" -DMINGW_PREFIX="\"$(patsubst /%,%,$(MINGW_PREFIX))\"" \
+		-DNOGDI -DHAVE_STRING_H -Icompat -Icompat/regex -Icompat/win32 -DSTRIP_EXTENSION=\".exe\"
 	BASIC_LDFLAGS = -IGNORE:4217 -IGNORE:4049 -NOLOGO -ENTRY:wmainCRTStartup -SUBSYSTEM:CONSOLE
 	# invalidcontinue.obj allows Git's source code to close the same file
 	# handle twice, or to access the osfhandle of an already-closed stdout
@@ -716,6 +713,7 @@ ifeq ($(uname_S),MINGW)
 	FSMONITOR_DAEMON_BACKEND = win32
 	FSMONITOR_OS_SETTINGS = win32
 
+	SKIP_DASHED_BUILT_INS = YabbaDabbaDoo
 	RUNTIME_PREFIX = YesPlease
 	HAVE_WPGMPTR = YesWeDo
 	NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease
@@ -754,26 +752,25 @@ ifeq ($(uname_S),MINGW)
         ifneq (,$(findstring -O,$(filter-out -O0 -Og,$(CFLAGS))))
 		BASIC_LDFLAGS += -Wl,--dynamicbase
         endif
-        ifeq (MINGW32,$(MSYSTEM))
-		prefix = /mingw32
-		HOST_CPU = i686
-		BASIC_LDFLAGS += -Wl,--pic-executable,-e,_mainCRTStartup
-        endif
-        ifeq (MINGW64,$(MSYSTEM))
-		prefix = /mingw64
-		HOST_CPU = x86_64
-		BASIC_LDFLAGS += -Wl,--pic-executable,-e,mainCRTStartup
-        else ifeq (CLANGARM64,$(MSYSTEM))
-		prefix = /clangarm64
-		HOST_CPU = aarch64
-		BASIC_LDFLAGS += -Wl,--pic-executable,-e,mainCRTStartup
-        else
-		COMPAT_CFLAGS += -D_USE_32BIT_TIME_T
-		BASIC_LDFLAGS += -Wl,--large-address-aware
+        ifneq (,$(MSYSTEM))
+                ifeq ($(MINGW_PREFIX),$(filter-out /%,$(MINGW_PREFIX)))
+			# Override if empty or does not start with a slash
+			MINGW_PREFIX := /$(shell echo '$(MSYSTEM)' | tr A-Z a-z)
+                endif
+		prefix = $(MINGW_PREFIX)
+		HOST_CPU = $(patsubst %-w64-mingw32,%,$(MINGW_CHOST))
+		BASIC_LDFLAGS += -Wl,--pic-executable
+		COMPAT_CFLAGS += -DDETECT_MSYS_TTY \
+			-DENSURE_MSYSTEM_IS_SET="\"$(MSYSTEM)\"" \
+			-DMINGW_PREFIX="\"$(patsubst /%,%,$(MINGW_PREFIX))\""
+                ifeq (MINGW32,$(MSYSTEM))
+			BASIC_LDFLAGS += -Wl,--large-address-aware
+                endif
+		# Move system config into top-level /etc/
+		ETC_GITCONFIG = ../etc/gitconfig
+		ETC_GITATTRIBUTES = ../etc/gitattributes
         endif
-	CC = gcc
-	COMPAT_CFLAGS += -D__USE_MINGW_ANSI_STDIO=0 -DDETECT_MSYS_TTY \
-		-fstack-protector-strong
+	COMPAT_CFLAGS += -D__USE_MINGW_ANSI_STDIO=0 -fstack-protector-strong
 	EXTLIBS += -lntdll
 	EXTRA_PROGRAMS += headless-git$X
 	INSTALL = /bin/install
@@ -781,11 +778,7 @@ ifeq ($(uname_S),MINGW)
 	HAVE_LIBCHARSET_H = YesPlease
 	USE_GETTEXT_SCHEME = fallthrough
 	USE_LIBPCRE = YesPlease
-        ifeq (/mingw64,$(subst 32,64,$(subst clangarm,mingw,$(prefix))))
-		# Move system config into top-level /etc/
-		ETC_GITCONFIG = ../etc/gitconfig
-		ETC_GITATTRIBUTES = ../etc/gitattributes
-        endif
+	NO_PYTHON =
 endif
 ifeq ($(uname_S),QNX)
 	COMPAT_CFLAGS += -DSA_RESTART=0
diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt
index a57c4b464fa456..7285bd9ac2c890 100644
--- a/contrib/buildsystems/CMakeLists.txt
+++ b/contrib/buildsystems/CMakeLists.txt
@@ -256,7 +256,14 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
 				_CONSOLE DETECT_MSYS_TTY STRIP_EXTENSION=".exe"  NO_SYMLINK_HEAD UNRELIABLE_FSTAT
 				NOGDI OBJECT_CREATION_MODE=1 __USE_MINGW_ANSI_STDIO=0
 				OVERRIDE_STRDUP MMAP_PREVENTS_DELETE USE_WIN32_MMAP
-				HAVE_WPGMPTR ENSURE_MSYSTEM_IS_SET HAVE_RTLGENRANDOM)
+				HAVE_WPGMPTR HAVE_RTLGENRANDOM)
+	if(CMAKE_GENERATOR_PLATFORM STREQUAL "x64")
+		add_compile_definitions(ENSURE_MSYSTEM_IS_SET="MINGW64" MINGW_PREFIX="mingw64")
+	elseif(CMAKE_GENERATOR_PLATFORM STREQUAL "arm64")
+		add_compile_definitions(ENSURE_MSYSTEM_IS_SET="CLANGARM64" MINGW_PREFIX="clangarm64")
+	elseif(CMAKE_GENERATOR_PLATFORM STREQUAL "x86")
+		add_compile_definitions(ENSURE_MSYSTEM_IS_SET="MINGW32" MINGW_PREFIX="mingw32")
+	endif()
 	list(APPEND compat_SOURCES
 		compat/mingw.c
 		compat/winansi.c
diff --git a/meson.build b/meson.build
index 7073d5844d2531..a8aba81e29b4e0 100644
--- a/meson.build
+++ b/meson.build
@@ -1318,7 +1318,6 @@ elif host_machine.system() == 'windows'
 
   libgit_c_args += [
     '-DDETECT_MSYS_TTY',
-    '-DENSURE_MSYSTEM_IS_SET',
     '-DNATIVE_CRLF',
     '-DNOGDI',
     '-DNO_POSIX_GOODIES',
@@ -1328,6 +1327,20 @@ elif host_machine.system() == 'windows'
     '-D__USE_MINGW_ANSI_STDIO=0',
   ]
 
+  msystem = get_option('msystem')
+  if msystem != ''
+    mingw_prefix = get_option('mingw_prefix')
+    if mingw_prefix == ''
+      mingw_prefix = msystem.to_lower()
+    elif mingw_prefix.startswith('/')
+      mingw_prefix = mingw_prefix.substring(1)
+    endif
+    libgit_c_args += [
+      '-DENSURE_MSYSTEM_IS_SET="' + msystem + '"',
+      '-DMINGW_PREFIX="' + mingw_prefix + '"'
+    ]
+  endif
+
   libgit_dependencies += compiler.find_library('ntdll')
   libgit_include_directories += 'compat/win32'
   if compiler.get_id() == 'msvc'
diff --git a/meson_options.txt b/meson_options.txt
index dc88f130d754a1..becf4689bf63b1 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -21,6 +21,10 @@ option('runtime_prefix', type: 'boolean', value: false,
   description: 'Resolve ancillary tooling and support files relative to the location of the runtime binary instead of hard-coding them into the binary.')
 option('sane_tool_path', type: 'array', value: [],
   description: 'An array of paths to pick up tools from in case the normal tools are broken or lacking.')
+option('msystem', type: 'string', value: '',
+  description: 'Fall-back on Windows when MSYSTEM is not set.')
+option('mingw_prefix', type: 'string', value: '',
+  description: 'Fall-back on Windows when MINGW_PREFIX is not set.')
 
 # Build information compiled into Git and other parts like documentation.
 option('build_date', type: 'string', value: '',
diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index 8545cdfab559b4..56faf5fe732ee0 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -602,7 +602,8 @@ test_expect_success !VALGRIND,RUNTIME_PREFIX,CAN_EXEC_IN_PWD 'RUNTIME_PREFIX wor
 	echo "echo HERE" | write_script pretend/libexec/git-core/git-here &&
 	GIT_EXEC_PATH= ./pretend/bin/git here >actual &&
 	echo HERE >expect &&
-	test_cmp expect actual'
+	test_cmp expect actual
+'
 
 test_expect_success !VALGRIND,RUNTIME_PREFIX,CAN_EXEC_IN_PWD '%(prefix)/ works' '
 	git config yes.path "%(prefix)/yes" &&
@@ -611,4 +612,34 @@ test_expect_success !VALGRIND,RUNTIME_PREFIX,CAN_EXEC_IN_PWD '%(prefix)/ works'
 	test_cmp expect actual
 '
 
+test_expect_success MINGW,RUNTIME_PREFIX 'MSYSTEM/PATH is adjusted if necessary' '
+	if test -z "$MINGW_PREFIX"
+	then
+		MINGW_PREFIX="/$(echo "${MSYSTEM:-MINGW64}" | tr A-Z a-z)"
+	fi &&
+	mkdir -p "$HOME"/bin pretend"$MINGW_PREFIX"/bin \
+		pretend"$MINGW_PREFIX"/libexec/git-core pretend/usr/bin &&
+	cp "$GIT_EXEC_PATH"/git.exe pretend"$MINGW_PREFIX"/bin/ &&
+	cp "$GIT_EXEC_PATH"/git.exe pretend"$MINGW_PREFIX"/libexec/git-core/ &&
+	# copy the .dll files, if any (happens when building via CMake)
+	if test -n "$(ls "$GIT_EXEC_PATH"/*.dll 2>/dev/null)"
+	then
+		cp "$GIT_EXEC_PATH"/*.dll pretend"$MINGW_PREFIX"/bin/ &&
+		cp "$GIT_EXEC_PATH"/*.dll pretend"$MINGW_PREFIX"/libexec/git-core/
+	fi &&
+	echo "env | grep MSYSTEM=" | write_script "$HOME"/bin/git-test-home &&
+	echo "echo ${MINGW_PREFIX#/}" | write_script pretend"$MINGW_PREFIX"/bin/git-test-bin &&
+	echo "echo usr" | write_script pretend/usr/bin/git-test-bin2 &&
+
+	(
+		MSYSTEM= &&
+		GIT_EXEC_PATH= &&
+		pretend"$MINGW_PREFIX"/libexec/git-core/git.exe test-home >actual &&
+		pretend"$MINGW_PREFIX"/libexec/git-core/git.exe test-bin >>actual &&
+		pretend"$MINGW_PREFIX"/bin/git.exe test-bin2 >>actual
+	) &&
+	test_write_lines MSYSTEM=$MSYSTEM "${MINGW_PREFIX#/}" usr >expect &&
+	test_cmp expect actual
+'
+
 test_done