wrt PATH:
"""
https://jira.mongodb.org/browse/SERVER-94430 Upstream respond:

> we intentionally do not ingest the environment PATH as this makes build
> reproducibility and hermiticity much harder. Instead, you should set the
> absolute paths to the tools you want to use on the command line, instead of
> relying on the PATH.

Gentoo bug https://bugs.gentoo.org/829340

In Gentoo, we have LLVM slotted and we put clang in /usr/lib/llvm/18/bin (or
whatever), not in /usr/bin, and if upstream strip PATH and construct it
themselves, they surely won't contain this location.

So we add PATH backup for scons.
"""
diff --git a/SConstruct b/SConstruct
index 2ebeb0e..44ce93a 100644
--- a/SConstruct
+++ b/SConstruct
@@ -3034,7 +3026,6 @@ if env.TargetOSIs('posix'):
     env.Append(
         CCFLAGS=[
             "-fasynchronous-unwind-tables",
-            "-g2" if not env.TargetOSIs('emscripten') else "-g",
             "-Wall",
             "-Wsign-compare",
             "-Wno-unknown-pragmas",
@@ -3101,6 +3092,8 @@ if env.TargetOSIs('posix'):
 
     # env.Append( " -Wconversion" ) TODO: this doesn't really work yet
     env.Append(CXXFLAGS=["-Woverloaded-virtual"])
+    env.Append(CXXFLAGS=os.environ['CXXFLAGS'])
+    env.Append(LINKFLAGS=os.environ['LDFLAGS'])
 
     # On OS X, clang doesn't want the pthread flag at link time, or it
     # issues warnings which make it impossible for us to declare link
@@ -3151,7 +3144,7 @@ if env.TargetOSIs('posix'):
         ], )
 
     #make scons colorgcc friendly
-    for key in ('HOME', 'TERM'):
+    for key in ('HOME', 'TERM', 'PATH'):
         try:
             env['ENV'][key] = os.environ[key]
         except KeyError:
@@ -3553,33 +3546,6 @@ def doConfigure(myenv):
         myenv.AddMethod(
             functools.partial(var_func, var=var, func=CheckFlag), f"Check{var}Supported")
 
-    if myenv.ToolchainIs('gcc', 'clang'):
-        # This tells clang/gcc to use the gold linker if it is available - we prefer the gold linker
-        # because it is much faster. Don't use it if the user has already configured another linker
-        # selection manually.
-        if any(flag.startswith('-fuse-ld=') for flag in env['LINKFLAGS']):
-            myenv.FatalError(
-                f"Use the '--linker' option instead of modifying the LINKFLAGS directly.")
-
-        linker_ld = get_option('linker')
-        if linker_ld == 'auto':
-            if not env.TargetOSIs('darwin', 'macOS'):
-                if not myenv.AddToLINKFLAGSIfSupported('-fuse-ld=lld'):
-                    myenv.FatalError(
-                        f"The recommended linker 'lld' is not supported with the current compiler configuration, you can try the 'gold' linker with '--linker=gold'."
-                    )
-        elif link_model.startswith("dynamic") and linker_ld == 'bfd':
-            # BFD is not supported due to issues with it causing warnings from some of
-            # the third party libraries that mongodb is linked with:
-            # https://jira.mongodb.org/browse/SERVER-49465
-            myenv.FatalError(f"Linker {linker_ld} is not supported with dynamic link model builds.")
-        else:
-            if not myenv.AddToLINKFLAGSIfSupported(f'-fuse-ld={linker_ld}'):
-                myenv.FatalError(f"Linker {linker_ld} could not be configured.")
-
-        if has_option('gcov') and myenv.AddToCCFLAGSIfSupported('-fprofile-update=single'):
-            myenv.AppendUnique(LINKFLAGS=['-fprofile-update=single'])
-
     detectCompiler = Configure(
         myenv,
         help=False,
@@ -5119,17 +5085,13 @@ def doConfigure(myenv):
         "BOOST_LOG_NO_SHORTHAND_NAMES",
         "BOOST_LOG_USE_NATIVE_SYSLOG",
         "BOOST_LOG_WITHOUT_THREAD_ATTR",
+        "BOOST_LOG_DYN_LINK",
         "BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS",
         "BOOST_SYSTEM_NO_DEPRECATED",
         "BOOST_THREAD_USES_DATETIME",
         ("BOOST_THREAD_VERSION", "5"),
     ])
 
-    if link_model.startswith("dynamic") and not link_model == 'dynamic-sdk':
-        conf.env.AppendUnique(CPPDEFINES=[
-            "BOOST_LOG_DYN_LINK",
-        ])
-
     if use_system_version_of_library("boost"):
         if not conf.CheckCXXHeader("boost/filesystem/operations.hpp"):
             myenv.ConfError("can't find boost headers")
@@ -5326,6 +5288,9 @@ def doConfigure(myenv):
 
     mongoc_mode = get_option('use-system-mongo-c')
     conf.env['MONGO_HAVE_LIBMONGOC'] = False
+    conf.env.ParseConfig('pkg-config libbson-1.0 libmongoc-1.0 --cflags')
+    conf.env['LIBDEPS_LIBBSON_SYSLIBDEP'] = 'bson-1.0'
+
     if mongoc_mode != 'off':
         if conf.CheckLibWithHeader(
             ["mongoc-1.0"],