diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/META-INF/MANIFEST.MF b/build/org.eclipse.cdt.managedbuilder.core.tests/META-INF/MANIFEST.MF
index 05ababd9fa4..cf5434aa22f 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/META-INF/MANIFEST.MF
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.cdt.managedbuilder.core.tests; singleton:=true
-Bundle-Version: 8.2.400.qualifier
+Bundle-Version: 8.2.300.qualifier
 Bundle-Activator: org.eclipse.cdt.managedbuilder.testplugin.CTestPlugin
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalc2/Benchmarks/sources.mk b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalc2/Benchmarks/sources.mk
index c09ad6b5fe9..673630dd080 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalc2/Benchmarks/sources.mk
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalc2/Benchmarks/sources.mk
@@ -6,7 +6,6 @@ ASM_SRCS :=
 C_SRCS := 
 OBJ_SRCS := 
 O_SRCS := 
-SX_SRCS := 
 S_UPPER_SRCS := 
 C_DEPS := 
 EXECUTABLES := 
diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalc3/Benchmarks/sources.mk b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalc3/Benchmarks/sources.mk
index c09ad6b5fe9..673630dd080 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalc3/Benchmarks/sources.mk
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalc3/Benchmarks/sources.mk
@@ -6,7 +6,6 @@ ASM_SRCS :=
 C_SRCS := 
 OBJ_SRCS := 
 O_SRCS := 
-SX_SRCS := 
 S_UPPER_SRCS := 
 C_DEPS := 
 EXECUTABLES := 
diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalcPreBuild/Benchmarks/sources.mk b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalcPreBuild/Benchmarks/sources.mk
index c09ad6b5fe9..673630dd080 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalcPreBuild/Benchmarks/sources.mk
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/depCalcProjects/test1DepCalcPreBuild/Benchmarks/sources.mk
@@ -6,7 +6,6 @@ ASM_SRCS :=
 C_SRCS := 
 OBJ_SRCS := 
 O_SRCS := 
-SX_SRCS := 
 S_UPPER_SRCS := 
 C_DEPS := 
 EXECUTABLES := 
diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test30Projects/test30_2/Benchmarks/sources.mk b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test30Projects/test30_2/Benchmarks/sources.mk
index b970622e5b6..af1ca6bbb9f 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test30Projects/test30_2/Benchmarks/sources.mk
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test30Projects/test30_2/Benchmarks/sources.mk
@@ -12,7 +12,6 @@ CXXM_SRCS :=
 CXX_SRCS := 
 C_UPPER_SRCS := 
 LOG_SRCS := 
-SX_SRCS := 
 S_UPPER_SRCS := 
 TAR_SRCS := 
 LOGFILE := 
diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test30Projects/testFileWithNoExtension/Benchmarks/sources.mk b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test30Projects/testFileWithNoExtension/Benchmarks/sources.mk
index f0941d6b561..407d90a33a6 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test30Projects/testFileWithNoExtension/Benchmarks/sources.mk
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test30Projects/testFileWithNoExtension/Benchmarks/sources.mk
@@ -6,7 +6,6 @@ ASM_SRCS :=
 C_SRCS := 
 OBJ_SRCS := 
 O_SRCS := 
-SX_SRCS := 
 S_UPPER_SRCS := 
 C_DEPS := 
 EXECUTABLES := 
diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test40Projects/test_40/Benchmarks/Test 4.0 ConfigName.Dbg/sources.mk b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test40Projects/test_40/Benchmarks/Test 4.0 ConfigName.Dbg/sources.mk
index 3441f930421..88fed6c1180 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test40Projects/test_40/Benchmarks/Test 4.0 ConfigName.Dbg/sources.mk	
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test40Projects/test_40/Benchmarks/Test 4.0 ConfigName.Dbg/sources.mk	
@@ -14,7 +14,6 @@ C_SRCS :=
 C_UPPER_SRCS := 
 OBJ_SRCS := 
 O_SRCS := 
-SX_SRCS := 
 S_UPPER_SRCS := 
 C++M_DEPS := 
 C++_DEPS := 
diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test40Projects/test_40/Benchmarks/dbg 2/sources.mk b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test40Projects/test_40/Benchmarks/dbg 2/sources.mk
index 3441f930421..88fed6c1180 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test40Projects/test_40/Benchmarks/dbg 2/sources.mk	
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/resources/test40Projects/test_40/Benchmarks/dbg 2/sources.mk	
@@ -14,7 +14,6 @@ C_SRCS :=
 C_UPPER_SRCS := 
 OBJ_SRCS := 
 O_SRCS := 
-SX_SRCS := 
 S_UPPER_SRCS := 
 C++M_DEPS := 
 C++_DEPS := 
diff --git a/build/org.eclipse.cdt.managedbuilder.core/META-INF/MANIFEST.MF b/build/org.eclipse.cdt.managedbuilder.core/META-INF/MANIFEST.MF
index 413d69ae823..30de811a100 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/META-INF/MANIFEST.MF
+++ b/build/org.eclipse.cdt.managedbuilder.core/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.cdt.managedbuilder.core; singleton:=true
-Bundle-Version: 9.6.300.qualifier
+Bundle-Version: 9.6.200.qualifier
 Bundle-Activator: org.eclipse.cdt.managedbuilder.core.ManagedBuilderCorePlugin
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/buildmodel/FileMacroExplicitSubstitutor.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/buildmodel/FileMacroExplicitSubstitutor.java
index 549c9f89b5a..c5e05e17c68 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/buildmodel/FileMacroExplicitSubstitutor.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/buildmodel/FileMacroExplicitSubstitutor.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2006, 2024 Intel Corporation and others.
+ * Copyright (c) 2006, 2010 Intel Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -10,7 +10,6 @@
  *
  * Contributors:
  * Intel Corporation - Initial API and implementation
- * John Dallaway - Provide getter for IConfiguration (#666)
  *******************************************************************************/
 
 package org.eclipse.cdt.managedbuilder.internal.buildmodel;
@@ -37,10 +36,6 @@ public FileMacroExplicitSubstitutor(IMacroContextInfo contextInfo, IConfiguratio
 		fBuilder = builder;
 	}
 
-	public IConfiguration getConfiguration() {
-		return fCfg;
-	}
-
 	/* (non-Javadoc)
 	 * @see org.eclipse.cdt.managedbuilder.internal.macros.DefaultMacroSubstitutor#resolveMacro(org.eclipse.cdt.managedbuilder.macros.IBuildMacro)
 	 */
diff --git a/build/org.eclipse.cdt.managedbuilder.gnu.ui/META-INF/MANIFEST.MF b/build/org.eclipse.cdt.managedbuilder.gnu.ui/META-INF/MANIFEST.MF
index 20b5c7faba7..58aee845d73 100644
--- a/build/org.eclipse.cdt.managedbuilder.gnu.ui/META-INF/MANIFEST.MF
+++ b/build/org.eclipse.cdt.managedbuilder.gnu.ui/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.cdt.managedbuilder.gnu.ui; singleton:=true
-Bundle-Version: 8.7.0.qualifier
+Bundle-Version: 8.6.100.qualifier
 Bundle-Activator: org.eclipse.cdt.managedbuilder.gnu.ui.GnuUIPlugin
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
diff --git a/build/org.eclipse.cdt.managedbuilder.gnu.ui/plugin.xml b/build/org.eclipse.cdt.managedbuilder.gnu.ui/plugin.xml
index 370c137b232..29596312772 100644
--- a/build/org.eclipse.cdt.managedbuilder.gnu.ui/plugin.xml
+++ b/build/org.eclipse.cdt.managedbuilder.gnu.ui/plugin.xml
@@ -565,7 +565,7 @@
                id="gnu.windres.option.preprocessor.undefined.symbols"/>
       </tool-->
       <tool
-            command="gcc"
+            command="as"
             name="%ToolName.assembler.gnu"
             outputFlag="-o"
             id="cdt.managedbuild.tool.gnu.assembler"
@@ -579,8 +579,6 @@
          <option
                name="%Option.Gnu.Assembler.Flags"
                category="gnu.asm.category.general"
-               commandGenerator="org.eclipse.cdt.managedbuilder.gnu.ui.GnuAsmFlagsCommandGenerator"
-               defaultValue="-c"
                valueType="string"
                id="gnu.both.asm.option.flags">
          </option>
@@ -609,7 +607,7 @@
                id="cdt.managedbuild.tool.gnu.assembler.input"
                languageId="org.eclipse.cdt.core.assembly"
                sourceContentType="org.eclipse.cdt.core.asmSource"
-               sources="s,sx,S">
+               sources="s,S">
          </inputType>
          <outputType
 			outputs="o"
diff --git a/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/ui/GnuAsmFlagsCommandGenerator.java b/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/ui/GnuAsmFlagsCommandGenerator.java
deleted file mode 100644
index 9f9dca78290..00000000000
--- a/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/ui/GnuAsmFlagsCommandGenerator.java
+++ /dev/null
@@ -1,97 +0,0 @@
-/*******************************************************************************
- * Copyright (c) 2024 John Dallaway and others.
- *
- * This program and the accompanying materials
- * are made available under the terms of the Eclipse Public License 2.0
- * which accompanies this distribution, and is available at
- * https://www.eclipse.org/legal/epl-2.0/
- *
- * SPDX-License-Identifier: EPL-2.0
- *
- * Contributors:
- *    John Dallaway - initial implementation (#666)
- *******************************************************************************/
-package org.eclipse.cdt.managedbuilder.gnu.ui;
-
-import java.util.regex.Pattern;
-
-import org.eclipse.cdt.core.cdtvariables.CdtVariableException;
-import org.eclipse.cdt.managedbuilder.core.BuildException;
-import org.eclipse.cdt.managedbuilder.core.IConfiguration;
-import org.eclipse.cdt.managedbuilder.core.IOption;
-import org.eclipse.cdt.managedbuilder.core.IOptionCommandGenerator;
-import org.eclipse.cdt.managedbuilder.core.ITool;
-import org.eclipse.cdt.managedbuilder.internal.buildmodel.FileMacroExplicitSubstitutor;
-import org.eclipse.cdt.managedbuilder.internal.macros.BuildfileMacroSubstitutor;
-import org.eclipse.cdt.utils.cdtvariables.CdtVariableResolver;
-import org.eclipse.cdt.utils.cdtvariables.IVariableSubstitutor;
-import org.eclipse.core.runtime.Platform;
-import org.eclipse.core.runtime.Status;
-
-/**
- * Assembler flags command generator.
- * This command generator supports managed build projects that were
- * created using older versions of the GNU toolchain build description
- * where assembly files were built by invoking the GNU "as" tool directly.
- * @noextend This class is not intended to be subclassed by clients.
- * @noinstantiate This class is not intended to be instantiated by clients.
- * @since 8.7
- */
-public class GnuAsmFlagsCommandGenerator implements IOptionCommandGenerator {
-
-	private static final String DO_NOT_LINK_FLAG = "-c"; //$NON-NLS-1$
-	private static final Pattern DO_NOT_LINK_PATTERN = Pattern.compile("(^|\\s)-c($|\\s)"); //$NON-NLS-1$
-	private static final Pattern ASM_FLAG_PATTERN = Pattern.compile("-[aDKLR]\\S*"); //$NON-NLS-1$
-
-	@Override
-	public String generateCommand(IOption option, IVariableSubstitutor macroSubstitutor) {
-		String toolCommand = getToolCommand(option, macroSubstitutor);
-		try {
-			if (null != toolCommand && IOption.STRING == option.getValueType() && option.getCommand().isEmpty()) {
-				String optionValue = option.getStringValue();
-				if (toolCommand.equals("gcc")) { //$NON-NLS-1$
-					// if the default assembler tool command has not been overridden
-					String command = CdtVariableResolver.resolveToString(optionValue, macroSubstitutor);
-					if (!DO_NOT_LINK_PATTERN.matcher(command).find()) {
-						// if the "-c" flag is not already present on the command line we
-						// assume the flags target the GNU "as" command line rather than the
-						// "gcc" command line so we add the "-c" flag and apply the "-Wa,"
-						// prefix to those flags that are intended only for the assembler
-						return DO_NOT_LINK_FLAG + " " + ASM_FLAG_PATTERN.matcher(command).replaceAll("-Wa,$0"); //$NON-NLS-1$ //$NON-NLS-2$
-					}
-				} else if (toolCommand.endsWith("as") && optionValue.equals(DO_NOT_LINK_FLAG)) { //$NON-NLS-1$
-					// if GNU "as" is called directly and the default assembler flags have
-					// not been overridden we remove the "-c" flag
-					return ""; //$NON-NLS-1$
-				}
-			}
-		} catch (BuildException | CdtVariableException e) {
-			Platform.getLog(getClass()).log(Status.error("Error generating GNU assembler command", e)); //$NON-NLS-1$
-		}
-		return null; // fallback to default command generator
-	}
-
-	private static String getToolCommand(IOption option, IVariableSubstitutor macroSubstitutor) {
-		// the option holder may be a super class of the assembler tool so we must
-		// locate the tool from the build configuration to obtain the correct tool command
-		IConfiguration config = getConfiguration(macroSubstitutor);
-		if (config != null) {
-			String optionHolderId = option.getOptionHolder().getId();
-			ITool[] tools = config.getToolsBySuperClassId(optionHolderId);
-			if (1 == tools.length) {
-				return tools[0].getToolCommand();
-			}
-		}
-		return null;
-	}
-
-	private static IConfiguration getConfiguration(IVariableSubstitutor macroSubstitutor) {
-		if (macroSubstitutor instanceof BuildfileMacroSubstitutor bms) { // case ToolSettingsPrefStore
-			return bms.getConfiguration();
-		} else if (macroSubstitutor instanceof FileMacroExplicitSubstitutor fmes) { // case BuildStep
-			return fmes.getConfiguration();
-		}
-		return null;
-	}
-
-}
diff --git a/core/org.eclipse.cdt.core/plugin.xml b/core/org.eclipse.cdt.core/plugin.xml
index ee3cbd91b5d..1f85cd2d0e4 100644
--- a/core/org.eclipse.cdt.core/plugin.xml
+++ b/core/org.eclipse.cdt.core/plugin.xml
@@ -625,7 +625,7 @@
 	  <!-- declares a content type for ASM Source files -->
       <content-type id="asmSource" name="%asmSourceName" 
           base-type="org.eclipse.core.runtime.text"
-          file-extensions="S,s,sx,asm,ASM"
+          file-extensions="S,s,asm,ASM"
           priority="high"/>
    </extension>