diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
index fb716ec56a..0fb0e1f4ff 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
@@ -389,10 +389,14 @@ class FormatOps(val tree: Tree, val initStyle: ScalafmtConfig) {
       case Decision(t @ FormatToken(_: T.Comma, right, _), splits)
           if owner == t.meta.leftOwner &&
             // TODO(olafur) what the right { decides to be single line?
-            !right.is[T.LeftBrace] &&
             // If comment is bound to comma, see unit/Comment.
             (!right.is[T.Comment] || t.newlinesBetween != 0) =>
-        splits.filter(_.modification.isNewline)
+        if (!right.is[T.LeftBrace])
+          splits.filter(_.modification.isNewline)
+        else if (!style.activeForEdition_2020_03)
+          splits
+        else
+          SplitTag.OneArgPerLine.activateOnly(splits)
     }
   }
 
diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
index e73526298e..1b05769a03 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
@@ -893,6 +893,26 @@ class Router(formatOps: FormatOps) {
             else isDefnSite(leftOwner) && !style.binPack.unsafeDefnSite
           } =>
         val close = matching(open)
+        val oneArgPerLineSplits =
+          if (!style.activeForEdition_2020_03) Seq.empty
+          else
+            (rightOwner match {
+              case _: Term.PartialFunction | Term.Block(
+                    List(_: Term.Function | _: Term.PartialFunction)
+                  ) =>
+                Seq(Split(Newline, 0))
+              case _ =>
+                val breakAfter =
+                  rhsOptimalToken(next(nextNonCommentSameLine(formatToken)))
+                val multiLine =
+                  newlinesOnlyBeforeClosePolicy(close)
+                    .orElse(decideNewlinesOnlyAfterToken(breakAfter))
+                Seq(
+                  Split(Newline, 0, policy = SingleLineBlock(close))
+                    .withOptimalToken(close, killOnFail = true),
+                  Split(Space, 1, policy = multiLine)
+                )
+            }).map(_.onlyFor(SplitTag.OneArgPerLine))
         def oneLineBody = open.pos.endLine == close.pos.startLine
         Seq(
           Split(Space, 0),
@@ -900,7 +920,7 @@ class Router(formatOps: FormatOps) {
             .onlyIf(newlines != 0 && oneLineBody)
             .withOptimalToken(close, killOnFail = true)
             .withPolicy(SingleLineBlock(close))
-        )
+        ) ++ oneArgPerLineSplits
       case FormatToken(_, _: T.LeftBrace, _) =>
         Seq(Split(Space, 0))
 
diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/SplitTag.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/SplitTag.scala
index ad22261c31..b35c32e3d1 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/SplitTag.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/SplitTag.scala
@@ -22,4 +22,6 @@ object SplitTag {
   case object Active extends Base
   case object Ignored extends Base
 
+  case object OneArgPerLine extends Custom
+
 }
diff --git a/scalafmt-tests/src/test/resources/default/Apply.stat b/scalafmt-tests/src/test/resources/default/Apply.stat
index 571dc182bc..7be167d10e 100644
--- a/scalafmt-tests/src/test/resources/default/Apply.stat
+++ b/scalafmt-tests/src/test/resources/default/Apply.stat
@@ -207,7 +207,8 @@ writeRead(
     // Use list because Array has a shitty toString
     { (b: List[Byte], os) =>
       os.writePosVarInt(b.size); os.writeBytes(b.toArray)
-    }, { is =>
+    },
+    { is =>
       val bytes = new Array[Byte](is.readPosVarInt)
       is.readFully(bytes)
       bytes.toList
diff --git a/scalafmt-tests/src/test/resources/newlines/beforeConfigSingleArgParenLambdaParamsF_danglingT.stat b/scalafmt-tests/src/test/resources/newlines/beforeConfigSingleArgParenLambdaParamsF_danglingT.stat
index f00d595278..c5c80d6015 100644
--- a/scalafmt-tests/src/test/resources/newlines/beforeConfigSingleArgParenLambdaParamsF_danglingT.stat
+++ b/scalafmt-tests/src/test/resources/newlines/beforeConfigSingleArgParenLambdaParamsF_danglingT.stat
@@ -719,7 +719,8 @@ object A {
     x.map(
       _.y(
         abcd,
-        { case ((abcdefghij, aswbasdfaw), asfda) => aswdf }, {
+        { case ((abcdefghij, aswbasdfaw), asfda) => aswdf },
+        {
           case (abcdefghij, sadfasdass) =>
             (
               asdfa.sadvfs(abcdefghij).get,
@@ -748,7 +749,8 @@ object A {
     x.map(
       _.y(
         abcd,
-        { { case ((abcdefghij, aswbasdfaw), asfda) => aswdf } }, {
+        { { case ((abcdefghij, aswbasdfaw), asfda) => aswdf } },
+        {
           {
             case (abcdefghij, sadfasdass) =>
               (
@@ -779,12 +781,12 @@ object A {
     x.map(
       _.y(
         abcd,
-        { case_abcdefghij_aswbasdfaw_asfda => aswdf }, {
-          case_abcdefghij_sadfasdass =>
-            (
-              asdfa.sadvfs(abcdefghij).get,
-              asdfasdfasfdasda.asdfas(asdfasdaas).get
-            )
+        { case_abcdefghij_aswbasdfaw_asfda => aswdf },
+        { case_abcdefghij_sadfasdass =>
+          (
+            asdfa.sadvfs(abcdefghij).get,
+            asdfasdfasfdasda.asdfas(asdfasdaas).get
+          )
         },
         foo
       )