diff --git a/HISTORY.rst b/HISTORY.rst
index 866b07c0..e89158bf 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -48,6 +48,7 @@ PlatformIO Core 5
   - Show project dependency licenses when building in the verbose mode
   - Fixed an issue when `LDF <https://docs.platformio.org/en/latest/librarymanager/ldf.html>`__ ignores the project `lib_deps <https://docs.platformio.org/en/latest/projectconf/section_env_library.html#lib-deps>`__ while resolving library dependencies (`issue #3598 <https://github.com/platformio/platformio-core/issues/3598>`_)
   - Fixed an issue with calling an extra script located outside a project (`issue #4220 <https://github.com/platformio/platformio-core/issues/4220>`_)
+  - Fixed an issue when GCC preprocessor was applied to the ".s" assembly files on case-sensitive OS such as Window OS (`issue #3917 <https://github.com/platformio/platformio-core/issues/3917>`_)
 
 * **Integration**
 
diff --git a/platformio/builder/main.py b/platformio/builder/main.py
index 49fb0612..439f84a6 100644
--- a/platformio/builder/main.py
+++ b/platformio/builder/main.py
@@ -49,10 +49,10 @@ clivars.AddVariables(
 DEFAULT_ENV_OPTIONS = dict(
     tools=[
         "ar",
-        "as",
         "cc",
         "c++",
         "link",
+        "pioasm",
         "platformio",
         "piotarget",
         "pioplatform",
diff --git a/platformio/builder/tools/pioasm.py b/platformio/builder/tools/pioasm.py
new file mode 100644
index 00000000..6af96bcd
--- /dev/null
+++ b/platformio/builder/tools/pioasm.py
@@ -0,0 +1,31 @@
+# Copyright (c) 2014-present PlatformIO <contact@platformio.org>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+
+import SCons.Tool.asm  # pylint: disable=import-error
+
+#
+# Resolve https://github.com/platformio/platformio-core/issues/3917
+# Avoid forcing .S to bare assembly on Windows OS
+#
+
+if ".S" in SCons.Tool.asm.ASSuffixes:
+    SCons.Tool.asm.ASSuffixes.remove(".S")
+if ".S" not in SCons.Tool.asm.ASPPSuffixes:
+    SCons.Tool.asm.ASPPSuffixes.append(".S")
+
+
+generate = SCons.Tool.asm.generate
+exists = SCons.Tool.asm.exists
diff --git a/platformio/builder/tools/platformio.py b/platformio/builder/tools/platformio.py
index 6f9f4729..a8763567 100644
--- a/platformio/builder/tools/platformio.py
+++ b/platformio/builder/tools/platformio.py
@@ -113,10 +113,6 @@ def ProcessProgramDeps(env):
 
     env.PrintConfiguration()
 
-    # fix ASM handling under non case-sensitive OS
-    if not Util.case_sensitive_suffixes(".s", ".S"):
-        env.Replace(AS="$CC", ASCOM="$ASPPCOM")
-
     # process extra flags from board
     if "BOARD" in env and "build.extra_flags" in env.BoardConfig():
         env.ProcessFlags(env.BoardConfig().get("build.extra_flags"))