diff --git a/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala b/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
index e1960f3122f3..3fe6ea4de819 100644
--- a/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
+++ b/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
@@ -402,14 +402,14 @@ class DottyBackendInterface(outputDirectory: AbstractFile, val superCallsMap: Ma
     else Some(ctx.settings.Ydumpclasses.value)
 
   def mainClass: Option[String] =
-    if (ctx.settings.mainClass.isDefault) None
-    else Some(ctx.settings.mainClass.value)
-  def setMainClass(name: String): Unit = ctx.settings.mainClass.update(name)
+    if (ctx.settings.XmainClass.isDefault) None
+    else Some(ctx.settings.XmainClass.value)
+  def setMainClass(name: String): Unit = ctx.settings.XmainClass.update(name)
 
 
-  def noForwarders: Boolean = ctx.settings.noForwarders.value
+  def noForwarders: Boolean = ctx.settings.XnoForwarders.value
   def debuglevel: Int = 3 // 0 -> no debug info; 1-> filename; 2-> lines; 3-> varnames
-  def settings_debug: Boolean = ctx.settings.debug.value
+  def settings_debug: Boolean = ctx.settings.Ydebug.value
   def targetPlatform: String = ctx.settings.target.value
 
   val perRunCaches: Caches = new Caches {
diff --git a/compiler/src/dotty/tools/backend/jvm/GenBCode.scala b/compiler/src/dotty/tools/backend/jvm/GenBCode.scala
index b627f001549e..4ce9926eb3b8 100644
--- a/compiler/src/dotty/tools/backend/jvm/GenBCode.scala
+++ b/compiler/src/dotty/tools/backend/jvm/GenBCode.scala
@@ -225,7 +225,7 @@ class GenBCodePipeline(val entryPoints: List[Symbol], val int: DottyBackendInter
           for (binary <- ctx.compilationUnit.pickled.get(claszSymbol.asClass)) {
             val store = if (mirrorC ne null) mirrorC else plainC
             val tasty =
-              if (ctx.settings.emitTasty.value) {
+              if (ctx.settings.YemitTasty.value) {
                 val outTastyFile = getFileForClassfile(outF, store.name, ".tasty")
                 val outstream = new DataOutputStream(outTastyFile.bufferedOutput)
                 try outstream.write(binary)
diff --git a/compiler/src/dotty/tools/dotc/Bench.scala b/compiler/src/dotty/tools/dotc/Bench.scala
index 836a575b6faf..927b638f77dc 100644
--- a/compiler/src/dotty/tools/dotc/Bench.scala
+++ b/compiler/src/dotty/tools/dotc/Bench.scala
@@ -20,7 +20,7 @@ object Bench extends Driver {
       val start = System.nanoTime()
       val r = super.doCompile(compiler, fileNames)
       println(s"time elapsed: ${(System.nanoTime - start) / 1000000}ms")
-      if (ctx.settings.prompt.value) {
+      if (ctx.settings.Xprompt.value) {
         print("hit <return> to continue >")
         System.in.read()
         println()
diff --git a/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala b/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
index 9903c6d75519..e4f3137458ef 100644
--- a/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
+++ b/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
@@ -51,35 +51,35 @@ class ScalaSettings extends Settings.SettingGroup {
   /** -X "Advanced" settings
    */
   val Xhelp = BooleanSetting("-X", "Print a synopsis of advanced options.")
-  val noForwarders = BooleanSetting("-Xno-forwarders", "Do not generate static forwarders in mirror classes.")
+  val XnoForwarders = BooleanSetting("-Xno-forwarders", "Do not generate static forwarders in mirror classes.")
   val XminImplicitSearchDepth = IntSetting("-Xmin-implicit-search-depth", "Set number of levels of implicit searches undertaken before checking for divergence.", 5)
   val xmaxInlines = IntSetting("-Xmax-inlines", "Maximal number of successive inlines", 32)
-  val maxClassfileName = IntSetting("-Xmax-classfile-name", "Maximum filename length for generated classes", 255, 72 to 255)
+  val XmaxClassfileName = IntSetting("-Xmax-classfile-name", "Maximum filename length for generated classes", 255, 72 to 255)
   val Xmigration = VersionSetting("-Xmigration", "Warn about constructs whose behavior may have changed since version.")
   val Xprint = PhasesSetting("-Xprint", "Print out program after")
-  val printtypes = BooleanSetting("-Xprint-types", "Print tree types (debugging option).")
+  val XprintTypes = BooleanSetting("-Xprint-types", "Print tree types (debugging option).")
   val XprintDiff = BooleanSetting("-Xprint-diff", "Print changed parts of the tree since last print.")
   val XprintDiffDel = BooleanSetting("-Xprint-diff-del", "Print chaged parts of the tree since last print including deleted parts.")
-  val prompt = BooleanSetting("-Xprompt", "Display a prompt after each error (debugging option).")
-  val mainClass = StringSetting("-Xmain-class", "path", "Class for manifest's Main-Class entry (only useful with -d <jar>)", "")
+  val Xprompt = BooleanSetting("-Xprompt", "Display a prompt after each error (debugging option).")
+  val XmainClass = StringSetting("-Xmain-class", "path", "Class for manifest's Main-Class entry (only useful with -d <jar>)", "")
   val XnoValueClasses = BooleanSetting("-Xno-value-classes", "Do not use value classes. Helps debugging.")
   val XreplLineWidth = IntSetting("-Xrepl-line-width", "Maximial number of columns per line for REPL output", 390)
   val XfatalWarnings = BooleanSetting("-Xfatal-warnings", "Fail the compilation if there are any warnings.")
   val XverifySignatures = BooleanSetting("-Xverify-signatures", "Verify generic signatures in generated bytecode.")
 
   /** -Y "Private" settings */
-  val overrideVars = BooleanSetting("-Yoverride-vars", "Allow vars to be overridden.")
+  val YoverrideVars = BooleanSetting("-Yoverride-vars", "Allow vars to be overridden.")
   val Yhelp = BooleanSetting("-Y", "Print a synopsis of private options.")
   val Ycheck = PhasesSetting("-Ycheck", "Check the tree at the end of")
   val YcheckMods = BooleanSetting("-Ycheck-mods", "Check that symbols and their defining trees have modifiers in sync")
-  val debug = BooleanSetting("-Ydebug", "Increase the quantity of debugging output.")
-  val debugTrace = BooleanSetting("-Ydebug-trace", "Trace core operations")
-  val debugFlags = BooleanSetting("-Ydebug-flags", "Print all flags of definitions")
-  val debugNames = BooleanSetting("-Ydebug-names", "Show internal representation of names")
-  val debugOwners = BooleanSetting("-Ydebug-owners", "Print all owners of definitions (requires -Yprint-syms)")
-  val termConflict = ChoiceSetting("-Yresolve-term-conflict", "strategy", "Resolve term conflicts", List("package", "object", "error"), "error")
-  val log = PhasesSetting("-Ylog", "Log operations during")
-  val emitTasty = BooleanSetting("-YemitTasty", "Generate tasty in separate *.tasty file.")
+  val Ydebug = BooleanSetting("-Ydebug", "Increase the quantity of debugging output.")
+  val YdebugTrace = BooleanSetting("-Ydebug-trace", "Trace core operations")
+  val YdebugFlags = BooleanSetting("-Ydebug-flags", "Print all flags of definitions")
+  val YdebugNames = BooleanSetting("-Ydebug-names", "Show internal representation of names")
+  val YdebugOwners = BooleanSetting("-Ydebug-owners", "Print all owners of definitions (requires -Yprint-syms)")
+  val YtermConflict = ChoiceSetting("-Yresolve-term-conflict", "strategy", "Resolve term conflicts", List("package", "object", "error"), "error")
+  val Ylog = PhasesSetting("-Ylog", "Log operations during")
+  val YemitTasty = BooleanSetting("-Yemit-tasty", "Generate tasty in separate *.tasty file.")
   val Ylogcp = BooleanSetting("-Ylog-classpath", "Output information about what classpath is being applied.")
   val YdisableFlatCpCaching  = BooleanSetting("-YdisableFlatCpCaching", "Do not cache flat classpath representation of classpath elements from jars across compiler instances.")
 
@@ -95,7 +95,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val YshowSuppressedErrors = BooleanSetting("-Yshow-suppressed-errors", "Also show follow-on errors and warnings that are normally supressed.")
   val YdetailedStats = BooleanSetting("-Ydetailed-stats", "show detailed internal compiler stats (needs Stats.enabled to be set to true).")
   val Yheartbeat = BooleanSetting("-Ydetailed-stats", "show heartbeat stack trace of compiler operations (needs Stats.enabled to be set to true).")
-  val Yprintpos = BooleanSetting("-Yprintpos", "show tree positions.")
+  val YprintPos = BooleanSetting("-Yprint-pos", "show tree positions.")
   val YnoDeepSubtypes = BooleanSetting("-Yno-deep-subtypes", "throw an exception on deep subtyping call stacks.")
   val YnoPatmatOpt = BooleanSetting("-Yno-patmat-opt", "disable all pattern matching optimizations.")
   val YplainPrinter = BooleanSetting("-Yplain-printer", "Pretty-print using a plain printer.")
@@ -111,16 +111,16 @@ class ScalaSettings extends Settings.SettingGroup {
   val YshowTreeIds = BooleanSetting("-Yshow-tree-ids", "Uniquely tag all tree nodes in debugging output.")
 
   /** Area-specific debug output */
-  val Yexplainlowlevel = BooleanSetting("-Yexplain-lowlevel", "When explaining type errors, show types at a lower level.")
+  val YexplainLowlevel = BooleanSetting("-Yexplain-lowlevel", "When explaining type errors, show types at a lower level.")
   val YnoDoubleBindings = BooleanSetting("-Yno-double-bindings", "Assert no namedtype is bound twice (should be enabled only if program is error-free).")
   val YshowVarBounds = BooleanSetting("-Yshow-var-bounds", "Print type variables with their bounds")
   val YnoInline = BooleanSetting("-Yno-inline", "Suppress inlining.")
 
   /** Linker specific flags */
-  val YoptPhases = PhasesSetting("-Yopt-phases", "Restrict the optimisation phases to execute under -optimise.")
-  val YoptFuel = IntSetting("-Yopt-fuel", "Maximum number of optimisations performed under -optimise.", -1)
   val optimise = BooleanSetting("-optimise", "Generates faster bytecode by applying local optimisations to the .program") withAbbreviation "-optimize"
   val Xlink = BooleanSetting("-Xlink", "Recompile library code with the application.")
+  val YoptPhases = PhasesSetting("-Yopt-phases", "Restrict the optimisation phases to execute under -optimise.")
+  val YoptFuel = IntSetting("-Yopt-fuel", "Maximum number of optimisations performed under -optimise.", -1)
 
   /** Dottydoc specific settings */
   val siteRoot = StringSetting(
diff --git a/compiler/src/dotty/tools/dotc/core/Contexts.scala b/compiler/src/dotty/tools/dotc/core/Contexts.scala
index baea88f0ebed..d7862a6e7ed1 100644
--- a/compiler/src/dotty/tools/dotc/core/Contexts.scala
+++ b/compiler/src/dotty/tools/dotc/core/Contexts.scala
@@ -368,7 +368,7 @@ object Contexts {
     def erasedTypes: Boolean = phase.erasedTypes
 
     /** Is the debug option set? */
-    def debug: Boolean = base.settings.debug.value
+    def debug: Boolean = base.settings.Ydebug.value
 
     /** Is the verbose option set? */
     def verbose: Boolean = base.settings.verbose.value
@@ -475,7 +475,7 @@ object Contexts {
     def setSetting[T](setting: Setting[T], value: T): this.type =
       setSettings(setting.updateIn(settingsState, value))
 
-    def setDebug = setSetting(base.settings.debug, true)
+    def setDebug = setSetting(base.settings.Ydebug, true)
   }
 
   implicit class ModeChanges(val c: Context) extends AnyVal {
diff --git a/compiler/src/dotty/tools/dotc/core/NameOps.scala b/compiler/src/dotty/tools/dotc/core/NameOps.scala
index b1c618a15a50..4a2d3092febc 100644
--- a/compiler/src/dotty/tools/dotc/core/NameOps.scala
+++ b/compiler/src/dotty/tools/dotc/core/NameOps.scala
@@ -30,7 +30,7 @@ object NameOps {
      */
     def apply(s: String)(implicit ctx: Context): String = {
       val marker = "$$$$"
-      val limit: Int = ctx.settings.maxClassfileName.value
+      val limit: Int = ctx.settings.XmaxClassfileName.value
       val MaxNameLength = (limit - 6) min 2 * (limit - 6 - 2 * marker.length - 32)
 
       def toMD5(s: String, edge: Int): String = {
diff --git a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
index 1703a0c834ff..ca7a889affeb 100644
--- a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -1959,7 +1959,7 @@ object SymDenotations {
       val (location, src) =
         if (file != null) (s" in $file", file.toString)
         else ("", "the signature")
-      val name = ctx.fresh.setSetting(ctx.settings.debugNames, true).nameString(denot.name)
+      val name = ctx.fresh.setSetting(ctx.settings.YdebugNames, true).nameString(denot.name)
       def errMsg =
         i"""bad symbolic reference. A signature$location
            |refers to $name in ${denot.owner.showKind} ${denot.owner.showFullName} which is not available.
diff --git a/compiler/src/dotty/tools/dotc/core/SymbolLoaders.scala b/compiler/src/dotty/tools/dotc/core/SymbolLoaders.scala
index 5bb2324372fc..da1716dd38d4 100644
--- a/compiler/src/dotty/tools/dotc/core/SymbolLoaders.scala
+++ b/compiler/src/dotty/tools/dotc/core/SymbolLoaders.scala
@@ -71,11 +71,11 @@ class SymbolLoaders {
       // offer a setting to resolve the conflict one way or the other.
       // This was motivated by the desire to use YourKit probes, which
       // require yjp.jar at runtime. See SI-2089.
-      if (ctx.settings.termConflict.isDefault)
+      if (ctx.settings.YtermConflict.isDefault)
         throw new TypeError(
           i"""$owner contains object and package with same name: $pname
              |one of them needs to be removed from classpath""")
-      else if (ctx.settings.termConflict.value == "package") {
+      else if (ctx.settings.YtermConflict.value == "package") {
         ctx.warning(
           s"Resolving package/object name conflict in favor of package ${preExisting.fullName}. The object will be inaccessible.")
         owner.asClass.delete(preExisting)
@@ -265,7 +265,7 @@ abstract class SymbolLoader extends LazyType {
     }
     try {
       val start = currentTime
-      if (ctx.settings.debugTrace.value)
+      if (ctx.settings.YdebugTrace.value)
         trace(s">>>> loading ${root.debugString}", _ => s"<<<< loaded ${root.debugString}") {
           doComplete(root)
         }
diff --git a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
index 7ce696d5412c..eec7130675e8 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -1625,7 +1625,7 @@ class ExplainingTypeComparer(initctx: Context) extends TypeComparer(initctx) {
     }
 
   private def show(res: Any) = res match {
-    case res: printing.Showable if !ctx.settings.Yexplainlowlevel.value => res.show
+    case res: printing.Showable if !ctx.settings.YexplainLowlevel.value => res.show
     case _ => String.valueOf(res)
   }
 
diff --git a/compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala b/compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala
index 1689ac392031..c57d6d1fbb3c 100644
--- a/compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala
@@ -326,7 +326,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
         }
         val trueDecls = otherDecls.filterNot(treatAsTypeArg)
         val declsText =
-          if (trueDecls.isEmpty || !ctx.settings.debug.value) Text()
+          if (trueDecls.isEmpty || !ctx.settings.Ydebug.value) Text()
           else dclsText(trueDecls)
         tparamsText ~ " extends " ~ toTextParents(tp.parents) ~ "{" ~ selfText ~ declsText ~
           "} at " ~ preText
@@ -485,12 +485,12 @@ class PlainPrinter(_ctx: Context) extends Printer {
         val elems =
           Text(node.productIterator.map(toTextElem).toList, ", ")
         val tpSuffix =
-          if (ctx.settings.printtypes.value && tree.hasType)
+          if (ctx.settings.XprintTypes.value && tree.hasType)
             " | " ~ toText(tree.typeOpt)
           else
             Text()
 
-        nodeName ~ "(" ~ elems ~ tpSuffix ~ ")" ~ (node.pos.toString provided ctx.settings.Yprintpos.value)
+        nodeName ~ "(" ~ elems ~ tpSuffix ~ ")" ~ (node.pos.toString provided ctx.settings.YprintPos.value)
       case _ =>
         tree.fallbackToText(this)
     }
diff --git a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
index 4a83041e35ae..e0fb5e7a9bb9 100644
--- a/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
@@ -24,7 +24,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
   /** A stack of enclosing DefDef, TypeDef, or ClassDef, or ModuleDefs nodes */
   private[this] var enclosingDef: untpd.Tree = untpd.EmptyTree
   private[this] var myCtx: Context = _ctx
-  private[this] var printPos = ctx.settings.Yprintpos.value
+  private[this] var printPos = ctx.settings.YprintPos.value
   private[this] val printLines = ctx.settings.printLines.value
   override protected[this] implicit def ctx: Context = myCtx
 
@@ -63,7 +63,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
   protected val PrintableFlags = (SourceModifierFlags | Label | Module | Local).toCommonFlags
 
   override def nameString(name: Name): String =
-    if (ctx.settings.debugNames.value) name.debugString else name.toString
+    if (ctx.settings.YdebugNames.value) name.debugString else name.toString
 
   override protected def simpleNameString(sym: Symbol): String =
     nameString(if (ctx.property(XprintMode).isEmpty) sym.originalName else sym.name)
@@ -257,7 +257,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     def modText(mods: untpd.Modifiers, kw: String): Text = { // DD
       val suppressKw = if (enclDefIsClass) mods is ParamAndLocal else mods is Param
       var flagMask =
-        if (ctx.settings.debugFlags.value) AnyFlags
+        if (ctx.settings.YdebugFlags.value) AnyFlags
         else if (suppressKw) PrintableFlags &~ Private
         else PrintableFlags
       if (homogenizedView && mods.flags.isTypeFlags) flagMask &~= Implicit // drop implicit from classes
@@ -283,7 +283,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     def dclTextOr(treeText: => Text) =
       if (useSymbol)
         annotsText(tree.symbol) ~~ dclText(tree.symbol) ~
-        ( " <in " ~ toText(tree.symbol.owner) ~ ">" provided ctx.settings.debugOwners.value)
+        ( " <in " ~ toText(tree.symbol.owner) ~ ">" provided ctx.settings.YdebugOwners.value)
       else treeText
 
     def idText(tree: untpd.Tree): Text = {
@@ -608,8 +608,8 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
       case _ => false
     }
 
-    if (ctx.settings.printtypes.value && tree.hasType) {
-      // add type to term nodes; replace type nodes with their types unless -Yprintpos is also set.
+    if (ctx.settings.XprintTypes.value && tree.hasType) {
+      // add type to term nodes; replace type nodes with their types unless -Yprint-pos is also set.
       def tp = tree.typeOpt match {
         case tp: TermRef if tree.isInstanceOf[RefTree] && !tp.denot.isOverloaded => tp.underlying
         case tp => tp
@@ -688,7 +688,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
   }
 
   override def toTextFlags(sym: Symbol) =
-    if (ctx.settings.debugFlags.value)
+    if (ctx.settings.YdebugFlags.value)
       super.toTextFlags(sym)
     else {
       var flags = sym.flagsUNSAFE
diff --git a/compiler/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/compiler/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 10ec402b8432..eb40cab959a2 100644
--- a/compiler/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -25,7 +25,7 @@ class ConsoleReporter(
     val didPrint = m match {
       case m: Error =>
         printMessage(messageAndPos(m.contained(), m.pos, diagnosticLevel(m)))
-        if (ctx.settings.prompt.value) displayPrompt()
+        if (ctx.settings.Xprompt.value) displayPrompt()
         true
       case m: ConditionalWarning if !m.enablingOption.value =>
         false
diff --git a/compiler/src/dotty/tools/dotc/reporting/Reporter.scala b/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
index 708a38512b32..73443871c2bb 100644
--- a/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -103,7 +103,7 @@ trait Reporting { this: Context =>
    *  "contains" here.
    */
   def log(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    if (this.settings.log.value.containsPhase(phase))
+    if (this.settings.Ylog.value.containsPhase(phase))
       echo(s"[log ${ctx.phasesStack.reverse.mkString(" -> ")}] $msg", pos)
 
   def debuglog(msg: => String): Unit =
@@ -123,7 +123,7 @@ trait Reporting { this: Context =>
   }
 
   def debugwarn(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    if (this.settings.debug.value) warning(msg, pos)
+    if (this.settings.Ydebug.value) warning(msg, pos)
 }
 
 /**
diff --git a/compiler/src/dotty/tools/dotc/reporting/trace.scala b/compiler/src/dotty/tools/dotc/reporting/trace.scala
index 6e10be9dc7f2..4d4c0578ffb9 100644
--- a/compiler/src/dotty/tools/dotc/reporting/trace.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/trace.scala
@@ -11,7 +11,7 @@ object trace {
 
   @inline
   def onDebug[TD](question: => String)(op: => TD)(implicit ctx: Context): TD =
-    conditionally(ctx.settings.debugTrace.value, question, false)(op)
+    conditionally(ctx.settings.YdebugTrace.value, question, false)(op)
 
   @inline
   def conditionally[TC](cond: Boolean, question: => String, show: Boolean)(op: => TC)(implicit ctx: Context): TC =
diff --git a/compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala b/compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala
index 532aef36b723..24d5da69afb0 100644
--- a/compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala
+++ b/compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala
@@ -565,7 +565,7 @@ private class ExtractAPICollector(implicit val ctx: Context) extends ThunkHolder
       // typed tree of the method as part of the signature we send to sbt.
       // To do this properly we would need a way to hash trees and types in
       // dotty itself.
-      val printTypesCtx = ctx.fresh.setSetting(ctx.settings.printtypes, true)
+      val printTypesCtx = ctx.fresh.setSetting(ctx.settings.XprintTypes, true)
       annots += marker(Inliner.bodyToInline(s).show(printTypesCtx).toString)
     }
 
diff --git a/compiler/src/dotty/tools/dotc/transform/ResolveSuper.scala b/compiler/src/dotty/tools/dotc/transform/ResolveSuper.scala
index 22a700bdb734..e347b1460fe1 100644
--- a/compiler/src/dotty/tools/dotc/transform/ResolveSuper.scala
+++ b/compiler/src/dotty/tools/dotc/transform/ResolveSuper.scala
@@ -107,7 +107,7 @@ object ResolveSuper {
     ctx.debuglog(i"starting rebindsuper from $base of ${acc.showLocated}: ${acc.info} in $bcs, name = $memberName")
     while (bcs.nonEmpty && sym == NoSymbol) {
       val other = bcs.head.info.nonPrivateDecl(memberName)
-      if (ctx.settings.debug.value)
+      if (ctx.settings.Ydebug.value)
         ctx.log(i"rebindsuper ${bcs.head} $other deferred = ${other.symbol.is(Deferred)}")
       sym = other.matchingDenotation(base.thisType, base.thisType.memberInfo(acc)).symbol
       bcs = bcs.tail
diff --git a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
index 07164bc68f8d..f93b0b77263b 100644
--- a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -218,7 +218,7 @@ object RefChecks {
             ";\n (Note that %s is abstract,\n  and is therefore overridden by concrete %s)".format(
               infoStringWithLocation(other),
               infoStringWithLocation(member))
-          else if (ctx.settings.debug.value)
+          else if (ctx.settings.Ydebug.value)
             err.typeMismatchMsg(memberTp(self), otherTp(self))
           else ""
 
@@ -355,7 +355,7 @@ object RefChecks {
         other.accessedFieldOrGetter.is(Mutable, butNot = Lazy)) {
         // !?! this is not covered by the spec. We need to resolve this either by changing the spec or removing the test here.
         // !!! is there a !?! convention? I'm !!!ing this to make sure it turns up on my searches.
-        if (!ctx.settings.overrideVars.value)
+        if (!ctx.settings.YoverrideVars.value)
           overrideError("cannot override a mutable variable")
       } else if (member.isAnyOverride &&
         !(member.owner.thisType.baseClasses exists (_ isSubClass other.owner)) &&
diff --git a/compiler/test/dotc/tests.scala b/compiler/test/dotc/tests.scala
index a81a8c12fce0..c626f0d80976 100644
--- a/compiler/test/dotc/tests.scala
+++ b/compiler/test/dotc/tests.scala
@@ -73,7 +73,7 @@ class tests extends CompilerTest {
     else List("-Ycheck:tailrec,resolveSuper,mixin,elimStaticThis,labelDef,simplify")
   } ++ checkOptions ++ classPath
 
-  val testPickling = List("-Xprint-types", "-Ytest-pickler", "-Ystop-after:pickler", "-Yprintpos")
+  val testPickling = List("-Xprint-types", "-Ytest-pickler", "-Ystop-after:pickler", "-Yprint-pos")
 
   val twice = List("#runs", "2")
   val staleSymbolError: List[String] = List()
diff --git a/compiler/test/dotty/tools/ShowClassTests.scala b/compiler/test/dotty/tools/ShowClassTests.scala
index fd01a6b59f34..12a86dc5d764 100644
--- a/compiler/test/dotty/tools/ShowClassTests.scala
+++ b/compiler/test/dotty/tools/ShowClassTests.scala
@@ -55,8 +55,8 @@ class ShowClassTests extends DottyTest {
     "dotty.tools.dotc.core.pickling.AbstractFileReader")
 
   def doTwice(test: Context => Unit)(implicit ctx: Context): Unit = {
-    test(ctx.fresh.setSetting(ctx.base.settings.debug, true))
-    test(ctx.fresh.setSetting(ctx.base.settings.debug, false))
+    test(ctx.fresh.setSetting(ctx.base.settings.Ydebug, true))
+    test(ctx.fresh.setSetting(ctx.base.settings.Ydebug, false))
   }
 
   def showPackage(pkg: TermSymbol)(implicit ctx: Context): Unit = {
diff --git a/compiler/test/dotty/tools/dotc/CompilationTests.scala b/compiler/test/dotty/tools/dotc/CompilationTests.scala
index cf9b12c26bd7..8326468c5ffa 100644
--- a/compiler/test/dotty/tools/dotc/CompilationTests.scala
+++ b/compiler/test/dotty/tools/dotc/CompilationTests.scala
@@ -96,7 +96,7 @@ class CompilationTests extends ParallelTesting {
     compileFilesInDir("../tests/pos-scala2", scala2Mode) +
     compileFilesInDir("../tests/pos", defaultOptions) +
     compileFilesInDir("../tests/pos-deep-subtype", allowDeepSubtypes) +
-    compileDir("../tests/pos/i1137-1", defaultOptions and "-YemitTasty") +
+    compileDir("../tests/pos/i1137-1", defaultOptions and "-Yemit-tasty") +
     compileFile(
       // succeeds despite -Xfatal-warnings because of -nowarn
       "../tests/neg/customArgs/xfatalWarnings.scala",
diff --git a/compiler/test/dotty/tools/dotc/IdempotencyTests.scala b/compiler/test/dotty/tools/dotc/IdempotencyTests.scala
index cd80f4e744c6..0d744feeb814 100644
--- a/compiler/test/dotty/tools/dotc/IdempotencyTests.scala
+++ b/compiler/test/dotty/tools/dotc/IdempotencyTests.scala
@@ -28,7 +28,7 @@ class IdempotencyTests extends ParallelTesting {
   @Category(Array(classOf[SlowTests]))
   @Test def idempotency: Unit = {
     implicit val testGroup: TestGroup = TestGroup("idempotency")
-    val opt = defaultOptions.and("-YemitTasty")
+    val opt = defaultOptions.and("-Yemit-tasty")
 
     def sourcesFrom(dir: Path) = CompilationTests.sources(Files.walk(dir))
 
diff --git a/compiler/test/dotty/tools/vulpix/TestConfiguration.scala b/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
index 938808c27efe..75c2f6c87089 100644
--- a/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
+++ b/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
@@ -54,7 +54,7 @@ object TestConfiguration {
   val picklingOptions = defaultUnoptimised and (
     "-Xprint-types",
     "-Ytest-pickler",
-    "-Yprintpos"
+    "-Yprint-pos"
   )
   val scala2Mode = defaultOptions and "-language:Scala2"
   val explicitUTF8 = defaultOptions and ("-encoding", "UTF8")
diff --git a/doc-tool/src/dotty/tools/dottydoc/core/ContextDottydoc.scala b/doc-tool/src/dotty/tools/dottydoc/core/ContextDottydoc.scala
index 161e799da7ce..4e62b2d58dfd 100644
--- a/doc-tool/src/dotty/tools/dottydoc/core/ContextDottydoc.scala
+++ b/doc-tool/src/dotty/tools/dottydoc/core/ContextDottydoc.scala
@@ -53,7 +53,7 @@ class ContextDottydoc extends ContextDocstrings {
   def echo(msg: String)(implicit ctx: Context): Unit = echo(msg, NoSourcePosition)
 
   def debug(msg: String, pos: SourcePosition)(implicit ctx: Context): Unit =
-    if (ctx.settings.debug.value) ctx.inform({
+    if (ctx.settings.Ydebug.value) ctx.inform({
       "[doc debug] " + msg
     }.toString, pos)
 
diff --git a/doc-tool/src/dotty/tools/dottydoc/staticsite/Template.scala b/doc-tool/src/dotty/tools/dottydoc/staticsite/Template.scala
index 75350cffd4d9..efa011e0a8a8 100644
--- a/doc-tool/src/dotty/tools/dottydoc/staticsite/Template.scala
+++ b/doc-tool/src/dotty/tools/dottydoc/staticsite/Template.scala
@@ -74,7 +74,7 @@ case class LiquidTemplate(path: String, content: SourceFile) extends Template wi
           None
         }
         case ex => {
-          if (true || ctx.settings.debug.value)
+          if (true || ctx.settings.Ydebug.value)
             throw ex
 
           None
diff --git a/language-server/src/dotty/tools/languageserver/DottyLanguageServer.scala b/language-server/src/dotty/tools/languageserver/DottyLanguageServer.scala
index 10445ac00bd1..3ba085b6c1c8 100644
--- a/language-server/src/dotty/tools/languageserver/DottyLanguageServer.scala
+++ b/language-server/src/dotty/tools/languageserver/DottyLanguageServer.scala
@@ -60,7 +60,7 @@ class DottyLanguageServer extends LanguageServer
       val configFile = new File(new URI(rootUri + '/' + IDE_CONFIG_FILE))
       val configs: List[ProjectConfig] = (new ObjectMapper).readValue(configFile, classOf[Array[ProjectConfig]]).toList
 
-      val defaultFlags = List(/*"-Yplain-printer","-Yprintpos"*/)
+      val defaultFlags = List(/*"-Yplain-printer","-Yprint-pos"*/)
 
       myDrivers = new mutable.HashMap
       for (config <- configs) {