diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/IMultiConfiguration.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/IMultiConfiguration.java
index f1307bb6bac..98498c8cb4d 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/IMultiConfiguration.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/IMultiConfiguration.java
@@ -14,7 +14,6 @@ import org.eclipse.cdt.core.settings.model.ICMultiItemsHolder;
 import org.eclipse.cdt.managedbuilder.buildproperties.IBuildProperty;
 import org.eclipse.cdt.managedbuilder.buildproperties.IBuildPropertyValue;
 import org.eclipse.cdt.managedbuilder.internal.core.Builder;
-import org.eclipse.cdt.newmake.core.IMakeCommonBuildInfo;
 
 /**
  * This class is to combine multiple configurations to one to support
@@ -26,12 +25,13 @@ import org.eclipse.cdt.newmake.core.IMakeCommonBuildInfo;
 public interface IMultiConfiguration extends IConfiguration, ICMultiItemsHolder {
 	
 	/**
-	 * Check if the configuration's builder is operating in parallel mode.
-	 * @return {@code true} if parallel mode is enabled, {@code false} otherwise.
+	 * Check if all configurations' builders are operating in parallel mode.
+	 * @return {@code true} if parallel mode is enabled for all configurations,
+	 *    {@code false} otherwise.
 	 */
 	boolean getParallelDef();
 	/**
-	 * Set parallel execution mode for the configuration's builder.
+	 * Set same parallel execution mode for all configurations' builders.
 	 * @see Builder#setParallelBuildOn(boolean)
 	 * 
 	 * @param parallel - the flag to enable or disable parallel mode.
@@ -39,18 +39,16 @@ public interface IMultiConfiguration extends IConfiguration, ICMultiItemsHolder
 	void setParallelDef(boolean parallel);
 
 	/**
-	 * Returns maximum number of parallel threads/jobs used by the configuration's builder.
-	 * Note that this function can return negative value to indicate  "optimal" number.
-	 * 
+	 * Returns maximum number of parallel threads/jobs used by the configurations' builders.
 	 * @see #setParallelDef(boolean)
-	 * @see Builder#getParallelizationNum()
 	 * 
-	 * @return - maximum number of parallel threads or jobs used by the builder or negative number.
-	 *    For exact interpretation see table in {@link IMakeCommonBuildInfo#getParallelizationNum()}
+	 * @return - maximum number of parallel threads or jobs used by each builder or 0 if the numbers
+	 *    don't match. 
 	 */
 	int getParallelNumber();
+
 	/**
-	 * Sets maximum number of parallel threads/jobs to be used by builder.
+	 * Sets maximum number of parallel threads/jobs to be used by each builder.
 	 * Note that the number will be set only if the builder is in "parallel"
 	 * mode.
 	 * 
@@ -61,10 +59,9 @@ public interface IMultiConfiguration extends IConfiguration, ICMultiItemsHolder
 	void setParallelNumber(int jobs);
 	
 	/**
-	 * returns the Internal Builder parallel mode
-	 * if true, internal builder will work in parallel mode 
-	 * otherwise it will use only one thread
-	 * @return boolean
+	 * Check if all configurations' internal builders are operating in parallel mode.
+	 * @return {@code true} if parallel mode is enabled for all configurations,
+	 *    {@code false} otherwise.
 	 * 
 	 * @deprecated since CDT 9.0. Use {@link #getParallelDef()}
 	 */
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/InternalBuildRunner.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/InternalBuildRunner.java
index 502c13732da..8c2cf096a4f 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/InternalBuildRunner.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/InternalBuildRunner.java
@@ -65,7 +65,7 @@ public class InternalBuildRunner extends AbstractBuildRunner {
 	public boolean invokeBuild(int kind, IProject project, IConfiguration configuration,
 			IBuilder builder, IConsole console, IMarkerGenerator markerGenerator,
 			IncrementalProjectBuilder projectBuilder, IProgressMonitor monitor) throws CoreException {
-		boolean isParallel = Math.abs(builder.getParallelizationNum()) > 1;
+		boolean isParallel = builder.getParallelizationNum() > 1;
 //		boolean buildIncrementaly = true;
 		boolean resumeOnErr = !builder.isStopOnError();
 
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/buildmodel/ParallelBuilder.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/buildmodel/ParallelBuilder.java
index 7dfcedf63c4..814e0310bf8 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/buildmodel/ParallelBuilder.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/buildmodel/ParallelBuilder.java
@@ -206,7 +206,7 @@ public class ParallelBuilder {
 		if(cwd == null)  cwd = des.getDefaultBuildDirLocation();
 		int threads = 1;
 		if (cfg instanceof Configuration) {
-			threads = Math.abs(((Configuration)cfg).getParallelNumber());
+			threads = ((Configuration)cfg).getParallelNumber();
 		}
 		ParallelBuilder builder = new ParallelBuilder(cwd, dirs, out, err, monitor, resumeOnErrors, buildIncrementally);
 		builder.enqueueAll(des);
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Builder.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Builder.java
index 22172cf3b8a..b9e27e02f97 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Builder.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Builder.java
@@ -67,6 +67,7 @@ import org.eclipse.cdt.managedbuilder.makegen.gnu.GnuMakefileGenerator;
 import org.eclipse.cdt.newmake.core.IMakeCommonBuildInfo;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.IncrementalProjectBuilder;
+import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IExtension;
@@ -123,7 +124,7 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 	// parallelization
 	private String parallelBuildCmd;
 	private Boolean isParallelBuildEnabled;
-	private Integer parallelJobsNumber; // negative number denotes "optimal" value, see getOptimalParallelJobNum()
+	private Integer parallelNumberAttribute; // negative number denotes "optimal" value, see getOptimalParallelJobNum()
 
 	private boolean isTest;
 	
@@ -331,7 +332,7 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 		ignoreErrCmd = builder.ignoreErrCmd;
 
 		isParallelBuildEnabled = builder.isParallelBuildEnabled;
-		parallelJobsNumber = builder.parallelJobsNumber;
+		parallelNumberAttribute = builder.parallelNumberAttribute;
 		parallelBuildCmd = builder.parallelBuildCmd;
 
 		if(builder.outputEntries != null){
@@ -381,9 +382,9 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 			} catch (CoreException e) {
 			}
 		}
-		if (getParallelizationNum() != builder.getParallelizationNum() && supportsParallelBuild()) {
+		if (getParallelizationNumAttribute() != builder.getParallelizationNumAttribute() && supportsParallelBuild()) {
 			try {
-				setParallelizationNum(builder.getParallelizationNum());
+				setParallelizationNum(builder.getParallelizationNumAttribute());
 			} catch (CoreException e) {
 			}
 		}
@@ -631,29 +632,29 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 
 	private void decodeParallelizationNumber(String value) {
 		if (VALUE_OPTIMAL.equals(value)) {
-			parallelJobsNumber = -getOptimalParallelJobNum();
+			parallelNumberAttribute = -getOptimalParallelJobNum();
 		} else if (VALUE_UNLIMITED.equals(value)) {
 			if (!isInternalBuilder()) {
-				parallelJobsNumber = Integer.MAX_VALUE;
+				parallelNumberAttribute = Integer.MAX_VALUE;
 			} else {
 				ManagedBuilderCorePlugin.error("'unlimited' number of jobs is not allowed for Internal Builder, switching to 'optimal'");
-				parallelJobsNumber = -getOptimalParallelJobNum();
+				parallelNumberAttribute = -getOptimalParallelJobNum();
 			}
 		} else {
 			try {
-				parallelJobsNumber = Integer.decode(value);
+				parallelNumberAttribute = Integer.decode(value);
 			} catch (NumberFormatException e) {
 				ManagedBuilderCorePlugin.log(e);
-				parallelJobsNumber = getOptimalParallelJobNum();
+				parallelNumberAttribute = getOptimalParallelJobNum();
 			}
-			if (parallelJobsNumber <= 0) {
+			if (parallelNumberAttribute <= 0) {
 				// compatibility with legacy representation - it was that inconsistent
 				if (isInternalBuilder()) {
 					// "optimal" for Internal Builder
-					parallelJobsNumber = -getOptimalParallelJobNum();
+					parallelNumberAttribute = -getOptimalParallelJobNum();
 				} else {
 					// unlimited for External Builder
-					parallelJobsNumber = Integer.MAX_VALUE;
+					parallelNumberAttribute = Integer.MAX_VALUE;
 				}
 			}
 		}
@@ -918,8 +919,8 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 
 		if (isParallelBuildEnabled != null)
 			element.setAttribute(ATTRIBUTE_PARALLEL_BUILD_ON, isParallelBuildEnabled.toString());
-		if (isParallelBuildOn() && parallelJobsNumber != null)
-			element.setAttribute(ATTRIBUTE_PARALLELIZATION_NUMBER, encodeParallelizationNumber(parallelJobsNumber));
+		if (isParallelBuildOn() && parallelNumberAttribute != null)
+			element.setAttribute(ATTRIBUTE_PARALLELIZATION_NUMBER, encodeParallelizationNumber(parallelNumberAttribute));
 
 		// Note: build file generator cannot be specified in a project file because
 		//       an IConfigurationElement is needed to load it!
@@ -1016,8 +1017,8 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 
 		if (isParallelBuildEnabled != null)
 			element.setAttribute(ATTRIBUTE_PARALLEL_BUILD_ON, isParallelBuildEnabled.toString());
-		if (isParallelBuildOn() && parallelJobsNumber != null)
-			element.setAttribute(ATTRIBUTE_PARALLELIZATION_NUMBER, encodeParallelizationNumber(parallelJobsNumber));
+		if (isParallelBuildOn() && parallelNumberAttribute != null)
+			element.setAttribute(ATTRIBUTE_PARALLELIZATION_NUMBER, encodeParallelizationNumber(parallelNumberAttribute));
 
 		// Note: build file generator cannot be specified in a project file because
 		//       an IConfigurationElement is needed to load it!
@@ -1095,10 +1096,11 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 	public String getArguments() {
 		String args = getArgumentsAttribute(); 
 		String stopOnErrCmd = getStopOnErrCmd(isStopOnError());
-		String parallelCmd = isParallelBuildOn() ? getParallelizationCmd(getParallelizationNum()) : EMPTY_STRING;
+		int parallelNum = getParallelizationNum();
+		String parallelCmd = isParallelBuildOn() ? getParallelizationCmd(parallelNum) : EMPTY_STRING;
 		
 		String reversedStopOnErrCmd = getStopOnErrCmd(!isStopOnError());
-		String reversedParallelBuildCmd = !isParallelBuildOn() ? getParallelizationCmd(getParallelizationNum()) : EMPTY_STRING;
+		String reversedParallelBuildCmd = !isParallelBuildOn() ? getParallelizationCmd(parallelNum) : EMPTY_STRING;
 		
 		args = removeCmd(args, reversedStopOnErrCmd);
 		args = removeCmd(args, reversedParallelBuildCmd);
@@ -1167,16 +1169,14 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 		return index;
 	}
 	
-	public String getParallelizationCmd(int num){
+	public String getParallelizationCmd(int num) {
 		String pattern = getParrallelBuildCmd();
-		if(pattern.length() == 0){
-			return EMPTY_STRING;
-		}if(num == 0){
+		if (pattern.length() == 0 || num == 0) {
 			return EMPTY_STRING;
 		}
 		// "unlimited" number of jobs results in not adding the number to parallelization cmd
 		// that behavior corresponds that of "make" flag "-j".
-		return processParallelPattern(pattern, num == Integer.MAX_VALUE, Math.abs(num));
+		return processParallelPattern(pattern, num == Integer.MAX_VALUE, num);
 	}
 	
 	/**
@@ -1188,6 +1188,8 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 	 * <br>Where # is num or empty if {@code empty} is {@code true})
 	 */
 	private String processParallelPattern(String pattern, boolean empty, int num){
+		Assert.isTrue(num > 0);
+		
 		int start = pattern.indexOf(PARALLEL_PATTERN_NUM_START);
 		int end = -1;
 		boolean hasStartChar = false;
@@ -2527,46 +2529,40 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 	}
 	
 	/**
-	 * {@inheritDoc}
-	 * 
-	 * Returns the number of parallel jobs to be used for a build.
+	 * Returns the internal representation of maximum number of parallel jobs
+	 * to be used for a build.
 	 * Note that "optimal" value is represented by negative number.
-	 * See the table at {@link IMakeCommonBuildInfo#getParallelizationNum()}. 
+	 * 
+	 * The value of the number is encoded as follows:
+	 * <pre>
+	 *  Status       Returns
+	 * No parallel      1       
+	 * Optimal       -CPU#       (negative number of processors) 
+	 * Specific        >0        (positive number)
+	 * Unlimited    Integer.MAX  (N/A for Internal Builder)
+	 * </pre>
 	 */
-	@Override
-	public int getParallelizationNum() {
+	public int getParallelizationNumAttribute() {
 		if (!isParallelBuildOn())
 			return 1;
-
-		if(parallelJobsNumber == null){
-			if(superClass != null){
-				return ((Builder)superClass).getParallelizationNum();
-			}
-			return 1;
-		}
-		return parallelJobsNumber.intValue();
-	}
-
-	public int getParallelizationNumAttribute(){
-		if(parallelJobsNumber == null){
+		
+		if(parallelNumberAttribute == null){
 			if(superClass != null){
 				return ((Builder)superClass).getParallelizationNumAttribute();
 			}
 			return 1;
 		}
-		return parallelJobsNumber.intValue();
+		return parallelNumberAttribute.intValue();
+	}
+	
+	@Override
+	public int getParallelizationNum() {
+		return Math.abs(getParallelizationNumAttribute());
 	}
 
-	/**
-	 * {@inheritDoc}
-	 * 
-	 * @param jobs - maximum number of jobs or threads. If the number is 0
-	 *    or negative, negative "optimal" number will be set, see
-	 *    {@link #getOptimalParallelJobNum()}.
-	 */
 	@Override
 	public void setParallelizationNum(int jobs) throws CoreException {
-		if (isParallelBuildOn() && (parallelJobsNumber == null || parallelJobsNumber != jobs)) {
+		if (isParallelBuildOn() && (parallelNumberAttribute == null || parallelNumberAttribute != jobs)) {
 			String curCmd = getParallelizationCmd(getParallelizationNum());
 			String args = getArgumentsAttribute();
 			String updatedArgs = removeCmd(args, curCmd);
@@ -2579,10 +2575,10 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 				jobs = -1;
 			}
 			if (jobs > 0) {
-				parallelJobsNumber = jobs;
+				parallelNumberAttribute = jobs;
 			} else {
 				// "optimal"
-				parallelJobsNumber = -getOptimalParallelJobNum();
+				parallelNumberAttribute = -getOptimalParallelJobNum();
 			}
 			setDirty(true);
 		}
@@ -2647,7 +2643,7 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 	 * 
 	 * @param on - the flag to enable or disable parallel mode.
 	 *    <br>{@code true} to enable, in this case the maximum number of jobs
-	 *      will be set to negative "optimal" number, see {@link #getOptimalParallelJobNum()}.
+	 *      will be set to "optimal" number, see {@link #getOptimalParallelJobNum()}.
 	 *    <br>{@code false} to disable, the number of jobs will be set to 1.
 	 */
 	@Override
@@ -2668,9 +2664,9 @@ public class Builder extends HoldsOptions implements IBuilder, IMatchKeyProvider
 
 		if (isParallelBuildEnabled) {
 			// "optimal"
-			parallelJobsNumber = -getOptimalParallelJobNum();
+			parallelNumberAttribute = -getOptimalParallelJobNum();
 		} else {
-			parallelJobsNumber = 1;
+			parallelNumberAttribute = 1;
 		}
 		setDirty(true);
 	}
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Configuration.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Configuration.java
index 271b1c94aef..5d552fc9594 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Configuration.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/Configuration.java
@@ -2273,8 +2273,8 @@ public class Configuration extends BuildObject implements IConfiguration, IBuild
 	 * mode.
 	 * 
 	 * @param jobs - maximum number of jobs or threads. If the number is 0
-	 *    or negative, negative "optimal" number will be set, see
-	 *    {@link Builder#getOptimalParallelJobNum()}.
+	 *    or negative, "optimal" number will be set,
+	 *    see {@link Builder#getOptimalParallelJobNum()}.
 	 */
 	public void setParallelNumber(int jobs){
 		try {
@@ -2286,13 +2286,9 @@ public class Configuration extends BuildObject implements IConfiguration, IBuild
 	
 	/**
 	 * Returns maximum number of parallel threads/jobs used by the configuration's builder.
-	 * Note that this function can return negative value to indicate  "optimal" number.
-	 * 
 	 * @see #setParallelDef(boolean)
-	 * @see Builder#getParallelizationNum()
 	 * 
-	 * @return - maximum number of parallel threads or jobs used by the builder or negative number.
-	 *    For exact interpretation see table in {@link IMakeCommonBuildInfo#getParallelizationNum()}
+	 * @return - maximum number of parallel threads or jobs used by the builder.
 	 */
 	public int getParallelNumber(){
 		return getBuilder().getParallelizationNum();
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/newmake/core/IMakeCommonBuildInfo.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/newmake/core/IMakeCommonBuildInfo.java
index 3d1a919d7fa..553c78170b9 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/newmake/core/IMakeCommonBuildInfo.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/newmake/core/IMakeCommonBuildInfo.java
@@ -44,15 +44,7 @@ public interface IMakeCommonBuildInfo {
 	boolean supportsStopOnError(boolean on);
 
 	/**
-	 * @return the current number of parallel jobs.
-	 * The value of the number is encoded as follows:
-	 * <pre>
-	 *  Status       Returns
-	 * No parallel      1       
-	 * Unlimited    Integer.MAX  (N/A for Internal Builder)
-	 * Optimal       -CPU#       (negative number of processors) 
-	 * Specific        >0        (positive number)
-	 * </pre>
+	 * @return the maximum number of parallel jobs to be used for build.
 	 */
 	int getParallelizationNum();
 
@@ -61,21 +53,25 @@ public interface IMakeCommonBuildInfo {
 	 * Note that the number will be set only if the builder is in "parallel"
 	 * mode.
 	 * 
-	 * @param jobs - number of jobs according table {@link #getParallelizationNum()}.
+	 * @param jobs - maximum number of jobs.
 	 *    Any number <=0 is treated as setting "optimal" property,
-	 *    the value of the number itself is ignored.
+	 *    the value of the number itself is ignored in this case.
 	 */
 	void setParallelizationNum(int jobs) throws CoreException;
+
 	/**
 	 * @return {@code true} if builder supports parallel build,
 	 *    {@code false} otherwise.
 	 */
+
 	boolean supportsParallelBuild();
+
 	/**
 	 * @return {@code true} if builder support for parallel build is enabled,
 	 *    {@code false} otherwise.
 	 */
 	boolean isParallelBuildOn();
+
 	/**
 	 * Set parallel execution mode for the builder.
 	 * @see Builder#setParallelBuildOn(boolean)
diff --git a/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/BuildBehaviourTab.java b/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/BuildBehaviourTab.java
index 0193eeb2362..543259ae733 100644
--- a/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/BuildBehaviourTab.java
+++ b/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/BuildBehaviourTab.java
@@ -25,7 +25,6 @@ import org.eclipse.cdt.managedbuilder.internal.core.Configuration;
 import org.eclipse.cdt.managedbuilder.internal.core.MultiConfiguration;
 import org.eclipse.cdt.managedbuilder.internal.ui.Messages;
 import org.eclipse.cdt.newmake.core.IMakeBuilderInfo;
-import org.eclipse.cdt.newmake.core.IMakeCommonBuildInfo;
 import org.eclipse.cdt.ui.newui.AbstractCPropertyTab;
 import org.eclipse.cdt.ui.newui.ICPropertyProvider;
 import org.eclipse.core.runtime.CoreException;
@@ -231,12 +230,12 @@ public class BuildBehaviourTab extends AbstractCBuildPropertyTab {
 	 *    0: isStopOnError
 	 *    1: supportsStopOnError(true)
 	 *    2: bld.supportsStopOnError(false)  
-	 *    3: cfg.getParallelDef()
+	 *    3: N/A
 	 * Mode 2:
 	 *    0: b.isAutoBuildEnable()
 	 *    1: b.isIncrementalBuildEnabled()
 	 *    2: b.isCleanBuildEnabled()
-	 *    3: getParallelDef()   
+	 *    3: N/A   
 	 */
 	 static int[] calc3states(ICPropertyProvider p, IConfiguration mcfg, int mode) {
 		if (p.isMultiCfg() && mcfg instanceof ICMultiItemsHolder) { 
@@ -253,8 +252,7 @@ public class BuildBehaviourTab extends AbstractCBuildPropertyTab {
 				(m1 ? bldr0.supportsStopOnError(true) : bldr0.isIncrementalBuildEnabled() );
 			b[2] = m0 ? bldr0.canKeepEnvironmentVariablesInBuildfile() : 
 				(m1 ? bldr0.supportsStopOnError(false) : bldr0.isCleanBuildEnabled());
-			b[3] = m0 ? bldr0.keepEnvironmentVariablesInBuildfile() : 
-				(m1 ? ((Configuration)cfgs[0]).getParallelDef() : getParallelDef(mcfg));
+			b[3] = m0 ? bldr0.keepEnvironmentVariablesInBuildfile() : false;
 			for (int i=1; i<cfgs.length; i++) {
 				IBuilder bldr = cfgs[i].getBuilder();
 				if (b[0] != (m0 ? bldr.isManagedBuildOn() : 
@@ -266,9 +264,7 @@ public class BuildBehaviourTab extends AbstractCBuildPropertyTab {
 				if (b[2] != (m0 ? bldr.canKeepEnvironmentVariablesInBuildfile() : 
 						(m1 ? bldr.supportsStopOnError(false) : bldr.isCleanBuildEnabled())))
 					res[2] = TRI_UNKNOWN;
-				if ((b[3] != (m0 ? bldr.keepEnvironmentVariablesInBuildfile() : 
-						(m1 ? ((Configuration)cfgs[i]).getParallelDef() : getParallelDef(mcfg))))
-						|| ((IMultiConfiguration) mcfg).getParallelNumber() == 0) {
+				if (b[3] != (m0 ? bldr.keepEnvironmentVariablesInBuildfile() : false)) {
 					res[3] = TRI_UNKNOWN;
 				}
 			}
@@ -304,60 +300,22 @@ public class BuildBehaviourTab extends AbstractCBuildPropertyTab {
 					bldr.supportsStopOnError(false));
 		}
 		
-		// Parallel build
-		boolean isParallelSupported = bldr.supportsParallelBuild();
-		boolean isExternalBuilder = ! isInternalBuilderEnabled();
 
-		b_parallel.setVisible(isParallelSupported);
-		b_parallelOptimal.setVisible(isParallelSupported);
-		b_parallelSpecific.setVisible(isParallelSupported);
-		b_parallelUnlimited.setVisible(isParallelSupported && isExternalBuilder);
-		s_parallelNumber.setVisible(isParallelSupported);
-
-		if (isParallelSupported) {
-			if (extStates == null) {
-				setTriSelection(b_parallel, getParallelDef());
-			} else {
-				setTriSelection(b_parallel, extStates[3]);
-			}
-			boolean isParallelSelected = b_parallel.getSelection();
-			int optimalParallelNumber = bldr.getOptimalParallelJobNum();
-
-			b_parallelOptimal.setText(MessageFormat.format(Messages.BuilderSettingsTab_UseOptimalJobs, optimalParallelNumber));
-			b_parallelOptimal.setEnabled(isParallelSelected);
-			b_parallelSpecific.setEnabled(isParallelSelected);
-			b_parallelUnlimited.setEnabled(isParallelSelected && isExternalBuilder);
-	
-			extStates = calc3states(page, icfg, 2);
-			if (extStates == null) {
-				setTriSelection(b_autoBuild, bldr.isAutoBuildEnable());
-				setTriSelection(b_cmdBuild, bldr.isIncrementalBuildEnabled());
-				setTriSelection(b_cmdClean, bldr.isCleanBuildEnabled());
-			} else { // multiple configurations selected
-				setTriSelection(b_autoBuild, extStates[0]);
-				setTriSelection(b_cmdBuild, extStates[1]);
-				setTriSelection(b_cmdClean, extStates[2]);
-			}
-			if ((extStates == null || extStates[3] != TRI_UNKNOWN) && isParallelSelected) {
-				// single configuration or matching multiple configurations here
-				int parallelNumber = getParallelNumber();
-				boolean isOptimal = parallelNumber <= 0;
-				boolean isUnlimited = parallelNumber == Integer.MAX_VALUE;
-				b_parallelOptimal.setSelection(isOptimal);
-				b_parallelSpecific.setSelection(!isOptimal && !isUnlimited);
-				b_parallelUnlimited.setSelection(isUnlimited);
-				s_parallelNumber.setEnabled(b_parallelSpecific.getEnabled() && b_parallelSpecific.getSelection());
-				s_parallelNumber.setSelection(s_parallelNumber.isEnabled() ? parallelNumber : optimalParallelNumber);
-			} else {
-				b_parallelOptimal.setSelection(true);
-				b_parallelSpecific.setSelection(false);
-				b_parallelUnlimited.setSelection(false);
-				s_parallelNumber.setEnabled(false);
-				s_parallelNumber.setSelection(optimalParallelNumber);
-			}
-		}
+		updateParallelBlock();
 		
 		// Build commands
+		extStates = calc3states(page, icfg, 2);
+		if (extStates != null) {
+			// multiple configurations selected
+			setTriSelection(b_autoBuild, extStates[0]);
+			setTriSelection(b_cmdBuild, extStates[1]);
+			setTriSelection(b_cmdClean, extStates[2]);
+		} else {
+			setTriSelection(b_autoBuild, bldr.isAutoBuildEnable());
+			setTriSelection(b_cmdBuild, bldr.isIncrementalBuildEnabled());
+			setTriSelection(b_cmdClean, bldr.isCleanBuildEnabled());
+		}
+
 		if (page.isMultiCfg()) {
 			MultiConfiguration mc = (MultiConfiguration)icfg;
 			t_autoBuild.setText(mc.getBuildAttribute(IBuilder.BUILD_TARGET_AUTO, EMPTY_STR));
@@ -377,7 +335,7 @@ public class BuildBehaviourTab extends AbstractCBuildPropertyTab {
 		((Control)t_cmdBuild.getData()).setVisible(external);
 		t_cmdClean.setVisible(external);
 		((Control)t_cmdClean.getData()).setVisible(external);
-		
+	
 		if (external) {
 			checkPressed(b_autoBuild, false);
 			checkPressed(b_cmdBuild, false);
@@ -386,6 +344,86 @@ public class BuildBehaviourTab extends AbstractCBuildPropertyTab {
 		canModify = true;
 	}
 	
+	private void updateParallelBlock() {
+		// note: for multi-config selection bldr is from Active cfg
+
+		boolean isAnyInternalBuilder = bldr.isInternalBuilder();
+		boolean isAnyExternalBuilder = ! bldr.isInternalBuilder();
+
+		boolean isParallelSupported = bldr.supportsParallelBuild();
+		boolean isParallelOn = bldr.isParallelBuildOn();
+		int triSelection = isParallelOn ? TRI_YES : TRI_NO;
+
+		int parallelizationNumInternal = bldr.getParallelizationNumAttribute();
+		int optimalParallelNumber = bldr.getOptimalParallelJobNum();
+		int parallelNumber = bldr.getParallelizationNum();
+		boolean isUnlimited = parallelizationNumInternal == Integer.MAX_VALUE;
+
+		if (icfg instanceof ICMultiItemsHolder) { 
+			IConfiguration[] cfgs = (IConfiguration[])((ICMultiItemsHolder)icfg).getItems();
+			boolean isAnyParallelOn = isParallelOn;
+			boolean isAnyParallelSupported = isParallelSupported;
+			boolean isParallelDiffers = false;
+			for (IConfiguration cfg : cfgs) {
+				Builder builder = (Builder) cfg.getBuilder();
+				isParallelDiffers = isParallelDiffers
+						|| builder.isParallelBuildOn() != isParallelOn
+						|| builder.getParallelizationNumAttribute() != parallelizationNumInternal;
+				
+				isAnyParallelOn = isAnyParallelOn || builder.isParallelBuildOn();
+				isAnyParallelSupported = isAnyParallelSupported || builder.supportsParallelBuild();
+				isAnyInternalBuilder = isAnyInternalBuilder || builder.isInternalBuilder();
+				isAnyExternalBuilder = isAnyExternalBuilder || !builder.isInternalBuilder();
+			}
+
+			// reset initial display to "optimal" to enhance user experience:
+			if ((!isParallelSupported && isAnyParallelSupported) // parallel is supported by other than Active cfg
+				|| (!isParallelOn && isAnyParallelOn) // prevent showing the 1 job as parallel in the spinner
+				|| (isUnlimited && isAnyInternalBuilder) // can't show "unlimited" as it won't be selectable if Internal Builder present
+				) {
+				isParallelSupported = true;
+				parallelizationNumInternal = -optimalParallelNumber;
+				parallelNumber = optimalParallelNumber;
+				isUnlimited = false;
+			}
+			if (isParallelSupported && isParallelDiffers) {
+				triSelection = TRI_UNKNOWN;
+			}
+		}
+		
+		b_parallel.setVisible(isParallelSupported);
+		b_parallelOptimal.setVisible(isParallelSupported);
+		b_parallelSpecific.setVisible(isParallelSupported);
+		b_parallelUnlimited.setVisible(isParallelSupported && isAnyExternalBuilder);
+		s_parallelNumber.setVisible(isParallelSupported);
+
+		if (isParallelSupported) {
+			setTriSelection(b_parallel, triSelection);
+			boolean isParallelSelected = b_parallel.getSelection();
+	
+			b_parallelOptimal.setText(MessageFormat.format(Messages.BuilderSettingsTab_UseOptimalJobs, optimalParallelNumber));
+			b_parallelOptimal.setEnabled(isParallelSelected);
+			b_parallelSpecific.setEnabled(isParallelSelected);
+			b_parallelUnlimited.setEnabled(isParallelSelected && !isAnyInternalBuilder);
+	
+			if (isParallelSelected) {
+				boolean isOptimal = parallelizationNumInternal <= 0;
+				
+				b_parallelOptimal.setSelection(isOptimal);
+				b_parallelSpecific.setSelection(!isOptimal && !isUnlimited);
+				b_parallelUnlimited.setSelection(isUnlimited);
+				s_parallelNumber.setEnabled(b_parallelSpecific.getEnabled() && b_parallelSpecific.getSelection());
+				s_parallelNumber.setSelection(s_parallelNumber.isEnabled() ? parallelNumber : optimalParallelNumber);
+			} else {
+				b_parallelOptimal.setSelection(true);
+				b_parallelSpecific.setSelection(false);
+				b_parallelUnlimited.setSelection(false);
+				s_parallelNumber.setEnabled(false);
+				s_parallelNumber.setSelection(optimalParallelNumber);
+			}
+		}
+	}
+
 	/**
 	 * Sets up text + corresponding button
 	 * Checkbox can be implemented either by Button or by TriButton
@@ -489,7 +527,7 @@ public class BuildBehaviourTab extends AbstractCBuildPropertyTab {
 			}
 			b2.setStopOnError(b1.isStopOnError());
 			b2.setParallelBuildOn(b1.isParallelBuildOn());
-			b2.setParallelizationNum(b1.getParallelizationNum());
+			b2.setParallelizationNum(((Builder) b1).getParallelizationNumAttribute());
 			if (b2.canKeepEnvironmentVariablesInBuildfile())
 				b2.setKeepEnvironmentVariablesInBuildfile(b1.keepEnvironmentVariablesInBuildfile());
 			((Builder)b2).setBuildPath(((Builder)b1).getBuildPathAttribute());
@@ -531,22 +569,6 @@ public class BuildBehaviourTab extends AbstractCBuildPropertyTab {
 		updateData(getResDesc());
 	}
 	
-	private static boolean getParallelDef(IConfiguration cfg) {
-		if (cfg instanceof Configuration) 
-			return ((Configuration)cfg).getParallelDef();
-		if (cfg instanceof IMultiConfiguration)
-			return ((IMultiConfiguration)cfg).getParallelDef();
-		return false;
-	}
-	
-	private boolean getParallelDef() {
-		if (icfg instanceof Configuration) 
-			return ((Configuration)icfg).getParallelDef();
-		if (icfg instanceof IMultiConfiguration)
-			return ((IMultiConfiguration)icfg).getParallelDef();
-		return false;
-	}
-	
 	private void setParallelDef(boolean def) {
 		if (icfg instanceof Configuration) 
 			((Configuration)icfg).setParallelDef(def);
@@ -554,16 +576,6 @@ public class BuildBehaviourTab extends AbstractCBuildPropertyTab {
 			((IMultiConfiguration)icfg).setParallelDef(def);
 	}
 	
-	/**
-	 * @see IMakeCommonBuildInfo#getParallelizationNum() for interpretation of the number.
-	 */
-	private int getParallelNumber() {
-		if (icfg instanceof Configuration) 
-			return ((Configuration)icfg).getParallelNumber();
-		if (icfg instanceof IMultiConfiguration)
-			return ((IMultiConfiguration)icfg).getParallelNumber();
-		return 0;
-	}
 	private void setParallelNumber(int num) {
 		if (icfg instanceof Configuration) 
 			((Configuration)icfg).setParallelNumber(num);
diff --git a/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/BuilderSettingsTab.java b/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/BuilderSettingsTab.java
index f36ce4480e8..70f95210099 100644
--- a/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/BuilderSettingsTab.java
+++ b/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/BuilderSettingsTab.java
@@ -87,6 +87,7 @@ public class BuilderSettingsTab extends AbstractCBuildPropertyTab {
 		setupLabel(g1, Messages.BuilderSettingsTab_5, 1, GridData.BEGINNING); 
 		t_buildCmd = setupBlock(g1, b_useDefault);
 		t_buildCmd.addModifyListener(new ModifyListener() {
+			@Override
 			public void modifyText(ModifyEvent e) {
 				if (! canModify)
 					return;
@@ -111,6 +112,7 @@ public class BuilderSettingsTab extends AbstractCBuildPropertyTab {
 		setupLabel(group_dir, Messages.BuilderSettingsTab_22, 1, GridData.BEGINNING); 
 		t_dir = setupText(group_dir, 1, GridData.FILL_HORIZONTAL);
 		t_dir.addModifyListener(new ModifyListener() {
+			@Override
 			public void modifyText(ModifyEvent e) {
 				if (canModify)
 					setBuildPath(t_dir.getText());