diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 5acaf560273..9b409a7e237 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -3404,77 +3404,14 @@ module ts {
                     emitSignatureParameters(node);
                 }
 
-                if (isSingleLineBlock(node.body)) {
+                if (isSingleLineBlock(node.body) || !node.body) {
                     write(" { }");
                 }
+                else if (node.body.kind === SyntaxKind.Block) {
+                    emitBlockFunctionBody(node, <Block>node.body);
+                }
                 else {
-                    write(" {");
-                    scopeEmitStart(node);
-
-                    if (!node.body) {
-                        writeLine();
-                        write("}");
-                    }
-                    else {
-                        increaseIndent();
-
-                        emitDetachedComments(node.body.kind === SyntaxKind.Block ? (<Block>node.body).statements : node.body);
-
-                        var startIndex = 0;
-                        if (node.body.kind === SyntaxKind.Block) {
-                            startIndex = emitDirectivePrologues((<Block>node.body).statements, /*startWithNewLine*/ true);
-                        }
-                        var outPos = writer.getTextPos();
-
-                        emitCaptureThisForNodeIfNecessary(node);
-                        emitDefaultValueAssignments(node);
-                        emitRestParameter(node);
-                        if (node.body.kind !== SyntaxKind.Block && outPos === writer.getTextPos()) {
-                            decreaseIndent();
-                            write(" ");
-                            emitStart(node.body);
-                            write("return ");
-
-                            // Don't emit comments on this body.  We'll have already taken care of it above 
-                            // when we called emitDetachedComments.
-                            emitNode(node.body, /*disableComments:*/ true);
-                            emitEnd(node.body);
-                            write(";");
-                            emitTempDeclarations(/*newLine*/ false);
-                            write(" ");
-                            emitStart(node.body);
-                            write("}");
-                            emitEnd(node.body);
-                        }
-                        else {
-                            if (node.body.kind === SyntaxKind.Block) {
-                                emitLinesStartingAt((<Block>node.body).statements, startIndex);
-                            }
-                            else {
-                                writeLine();
-                                emitLeadingComments(node.body);
-                                write("return ");
-                                emit(node.body, /*disableComments:*/ true);
-                                write(";");
-                                emitTrailingComments(node.body);
-                            }
-                            emitTempDeclarations(/*newLine*/ true);
-                            writeLine();
-                            if (node.body.kind === SyntaxKind.Block) {
-                                emitLeadingCommentsOfPosition((<Block>node.body).statements.end);
-                                decreaseIndent();
-                                emitToken(SyntaxKind.CloseBraceToken, (<Block>node.body).statements.end);
-                            }
-                            else {
-                                decreaseIndent();
-                                emitStart(node.body);
-                                write("}");
-                                emitEnd(node.body);
-                            }
-                        }
-                    }
-
-                    scopeEmitEnd();
+                    emitExpressionFunctionBody(node, <Expression>node.body);
                 }
 
                 if (node.flags & NodeFlags.Export) {
@@ -3486,11 +3423,86 @@ module ts {
                     emitEnd(node);
                     write(";");
                 }
+
                 tempCount = saveTempCount;
                 tempVariables = saveTempVariables;
                 tempParameters = saveTempParameters;
             }
 
+            // Returns true if any preamble code was emitted.
+            function emitFunctionBodyPreamble(node: FunctionLikeDeclaration): void {
+                emitCaptureThisForNodeIfNecessary(node);
+                emitDefaultValueAssignments(node);
+                emitRestParameter(node);
+            }
+
+            function emitExpressionFunctionBody(node: FunctionLikeDeclaration, body: Expression) {
+                write(" {");
+                scopeEmitStart(node);
+
+                increaseIndent();
+                var outPos = writer.getTextPos();
+                emitDetachedComments(node.body);
+                emitFunctionBodyPreamble(node);
+                var preambleEmitted = writer.getTextPos() !== outPos;
+                decreaseIndent();
+
+                // If we didn't have to emit any preamble code, then attempt to keep the arrow
+                // function on one line.
+                if (!preambleEmitted && isOnSameLine(node, body)) {
+                    write(" ");
+                    emitStart(body);
+                    write("return ");
+
+                    // Don't emit comments on this body.  We'll have already taken care of it above 
+                    // when we called emitDetachedComments.
+                    emitNode(body, /*disableComments:*/ true);
+                    emitEnd(body);
+                    write(";");
+                    emitTempDeclarations(/*newLine*/ false);
+                    write(" ");
+                }
+                else {
+                    increaseIndent();
+                    writeLine();
+                    emitLeadingComments(node.body);
+                    write("return ");
+                    emit(node.body, /*disableComments:*/ true);
+                    write(";");
+                    emitTrailingComments(node.body);
+
+                    emitTempDeclarations(/*newLine*/ true);
+                    decreaseIndent();
+                    writeLine();
+                }
+
+                emitStart(node.body);
+                write("}");
+                emitEnd(node.body);
+
+                scopeEmitEnd();
+            }
+
+            function emitBlockFunctionBody(node: FunctionLikeDeclaration, body: Block) {
+                write(" {");
+                scopeEmitStart(node);
+
+                increaseIndent();
+                emitDetachedComments(body.statements);
+                var startIndex = emitDirectivePrologues(body.statements, /*startWithNewLine*/ true);
+
+                emitFunctionBodyPreamble(node);
+                emitLinesStartingAt(body.statements, startIndex);
+                emitTempDeclarations(/*newLine*/ true);
+
+                writeLine();
+                emitLeadingCommentsOfPosition(body.statements.end);
+                decreaseIndent();
+                emitToken(SyntaxKind.CloseBraceToken, body.statements.end);
+
+                scopeEmitEnd();
+            }
+
             function findInitialSuperCall(ctor: ConstructorDeclaration): ExpressionStatement {
                 if (ctor.body) {
                     var statement = (<Block>ctor.body).statements[0];
diff --git a/tests/baselines/reference/FunctionPropertyAssignments4_es6.js b/tests/baselines/reference/FunctionPropertyAssignments4_es6.js
index 595f7fc9124..71076523414 100644
--- a/tests/baselines/reference/FunctionPropertyAssignments4_es6.js
+++ b/tests/baselines/reference/FunctionPropertyAssignments4_es6.js
@@ -2,5 +2,4 @@
 var v = { * }
 
 //// [FunctionPropertyAssignments4_es6.js]
-var v = { : function () {
-} };
+var v = { : function () { } };
diff --git a/tests/baselines/reference/accessorWithoutBody1.js b/tests/baselines/reference/accessorWithoutBody1.js
index 37f0ecbcfee..e06e305e161 100644
--- a/tests/baselines/reference/accessorWithoutBody1.js
+++ b/tests/baselines/reference/accessorWithoutBody1.js
@@ -2,5 +2,4 @@
 var v = { get foo() }
 
 //// [accessorWithoutBody1.js]
-var v = { get foo() {
-} };
+var v = { get foo() { } };
diff --git a/tests/baselines/reference/accessorWithoutBody2.js b/tests/baselines/reference/accessorWithoutBody2.js
index 9dc34c1e744..3b5a821d580 100644
--- a/tests/baselines/reference/accessorWithoutBody2.js
+++ b/tests/baselines/reference/accessorWithoutBody2.js
@@ -2,5 +2,4 @@
 var v = { set foo(a) }
 
 //// [accessorWithoutBody2.js]
-var v = { set foo(a) {
-} };
+var v = { set foo(a) { } };
diff --git a/tests/baselines/reference/commentOnSimpleArrowFunctionBody1.js b/tests/baselines/reference/commentOnSimpleArrowFunctionBody1.js
index dc9bac84fa5..39f967555bf 100644
--- a/tests/baselines/reference/commentOnSimpleArrowFunctionBody1.js
+++ b/tests/baselines/reference/commentOnSimpleArrowFunctionBody1.js
@@ -11,4 +11,7 @@ Foo(() =>
 //// [commentOnSimpleArrowFunctionBody1.js]
 function Foo(x) {
 }
-Foo(function () { return 127; });
+Foo(function () {
+    // do something
+    return 127;
+});
diff --git a/tests/baselines/reference/genericsAndHigherOrderFunctions.js b/tests/baselines/reference/genericsAndHigherOrderFunctions.js
index 1086bd78c54..f2e6ef58f22 100644
--- a/tests/baselines/reference/genericsAndHigherOrderFunctions.js
+++ b/tests/baselines/reference/genericsAndHigherOrderFunctions.js
@@ -19,5 +19,13 @@ var foo: <K, N>(g: (x: K) => N) =>
 
 //// [genericsAndHigherOrderFunctions.js]
 // no errors expected
-var combine = function (f) { return function (g) { return function (x) { return f(g(x)); }; }; };
-var foo = function (g) { return function (h) { return function (f) { return h(combine(f)(g)); }; }; };
+var combine = function (f) {
+    return function (g) {
+        return function (x) { return f(g(x)); };
+    };
+};
+var foo = function (g) {
+    return function (h) {
+        return function (f) { return h(combine(f)(g)); };
+    };
+};
diff --git a/tests/baselines/reference/giant.js b/tests/baselines/reference/giant.js
index 7f2c2453b0f..a5109b6e113 100644
--- a/tests/baselines/reference/giant.js
+++ b/tests/baselines/reference/giant.js
@@ -706,44 +706,38 @@ define(["require", "exports"], function (require, exports) {
         C.prototype.rF = function () { };
         C.prototype.pgF = function () { };
         Object.defineProperty(C.prototype, "pgF", {
-            get: function () {
-            },
+            get: function () { },
             enumerable: true,
             configurable: true
         });
         C.prototype.psF = function (param) { };
         Object.defineProperty(C.prototype, "psF", {
-            set: function (param) {
-            },
+            set: function (param) { },
             enumerable: true,
             configurable: true
         });
         C.prototype.rgF = function () { };
         Object.defineProperty(C.prototype, "rgF", {
-            get: function () {
-            },
+            get: function () { },
             enumerable: true,
             configurable: true
         });
         C.prototype.rsF = function (param) { };
         Object.defineProperty(C.prototype, "rsF", {
-            set: function (param) {
-            },
+            set: function (param) { },
             enumerable: true,
             configurable: true
         });
         C.tF = function () { };
         C.tsF = function (param) { };
         Object.defineProperty(C, "tsF", {
-            set: function (param) {
-            },
+            set: function (param) { },
             enumerable: true,
             configurable: true
         });
         C.tgF = function () { };
         Object.defineProperty(C, "tgF", {
-            get: function () {
-            },
+            get: function () { },
             enumerable: true,
             configurable: true
         });
@@ -761,44 +755,38 @@ define(["require", "exports"], function (require, exports) {
             C.prototype.rF = function () { };
             C.prototype.pgF = function () { };
             Object.defineProperty(C.prototype, "pgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
             C.prototype.psF = function (param) { };
             Object.defineProperty(C.prototype, "psF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             C.prototype.rgF = function () { };
             Object.defineProperty(C.prototype, "rgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
             C.prototype.rsF = function (param) { };
             Object.defineProperty(C.prototype, "rsF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             C.tF = function () { };
             C.tsF = function (param) { };
             Object.defineProperty(C, "tsF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             C.tgF = function () { };
             Object.defineProperty(C, "tgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
@@ -845,44 +833,38 @@ define(["require", "exports"], function (require, exports) {
             eC.prototype.rF = function () { };
             eC.prototype.pgF = function () { };
             Object.defineProperty(eC.prototype, "pgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
             eC.prototype.psF = function (param) { };
             Object.defineProperty(eC.prototype, "psF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             eC.prototype.rgF = function () { };
             Object.defineProperty(eC.prototype, "rgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
             eC.prototype.rsF = function (param) { };
             Object.defineProperty(eC.prototype, "rsF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             eC.tF = function () { };
             eC.tsF = function (param) { };
             Object.defineProperty(eC, "tsF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             eC.tgF = function () { };
             Object.defineProperty(eC, "tgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
@@ -932,44 +914,38 @@ define(["require", "exports"], function (require, exports) {
         eC.prototype.rF = function () { };
         eC.prototype.pgF = function () { };
         Object.defineProperty(eC.prototype, "pgF", {
-            get: function () {
-            },
+            get: function () { },
             enumerable: true,
             configurable: true
         });
         eC.prototype.psF = function (param) { };
         Object.defineProperty(eC.prototype, "psF", {
-            set: function (param) {
-            },
+            set: function (param) { },
             enumerable: true,
             configurable: true
         });
         eC.prototype.rgF = function () { };
         Object.defineProperty(eC.prototype, "rgF", {
-            get: function () {
-            },
+            get: function () { },
             enumerable: true,
             configurable: true
         });
         eC.prototype.rsF = function (param) { };
         Object.defineProperty(eC.prototype, "rsF", {
-            set: function (param) {
-            },
+            set: function (param) { },
             enumerable: true,
             configurable: true
         });
         eC.tF = function () { };
         eC.tsF = function (param) { };
         Object.defineProperty(eC, "tsF", {
-            set: function (param) {
-            },
+            set: function (param) { },
             enumerable: true,
             configurable: true
         });
         eC.tgF = function () { };
         Object.defineProperty(eC, "tgF", {
-            get: function () {
-            },
+            get: function () { },
             enumerable: true,
             configurable: true
         });
@@ -988,44 +964,38 @@ define(["require", "exports"], function (require, exports) {
             C.prototype.rF = function () { };
             C.prototype.pgF = function () { };
             Object.defineProperty(C.prototype, "pgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
             C.prototype.psF = function (param) { };
             Object.defineProperty(C.prototype, "psF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             C.prototype.rgF = function () { };
             Object.defineProperty(C.prototype, "rgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
             C.prototype.rsF = function (param) { };
             Object.defineProperty(C.prototype, "rsF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             C.tF = function () { };
             C.tsF = function (param) { };
             Object.defineProperty(C, "tsF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             C.tgF = function () { };
             Object.defineProperty(C, "tgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
@@ -1072,44 +1042,38 @@ define(["require", "exports"], function (require, exports) {
             eC.prototype.rF = function () { };
             eC.prototype.pgF = function () { };
             Object.defineProperty(eC.prototype, "pgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
             eC.prototype.psF = function (param) { };
             Object.defineProperty(eC.prototype, "psF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             eC.prototype.rgF = function () { };
             Object.defineProperty(eC.prototype, "rgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
             eC.prototype.rsF = function (param) { };
             Object.defineProperty(eC.prototype, "rsF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             eC.tF = function () { };
             eC.tsF = function (param) { };
             Object.defineProperty(eC, "tsF", {
-                set: function (param) {
-                },
+                set: function (param) { },
                 enumerable: true,
                 configurable: true
             });
             eC.tgF = function () { };
             Object.defineProperty(eC, "tgF", {
-                get: function () {
-                },
+                get: function () { },
                 enumerable: true,
                 configurable: true
             });
diff --git a/tests/baselines/reference/lambdaASIEmit.js b/tests/baselines/reference/lambdaASIEmit.js
index 551aa5f93dd..49672b75c7c 100644
--- a/tests/baselines/reference/lambdaASIEmit.js
+++ b/tests/baselines/reference/lambdaASIEmit.js
@@ -12,4 +12,7 @@ Foo(() =>
 //// [lambdaASIEmit.js]
 function Foo(x) {
 }
-Foo(function () { return 127; });
+Foo(function () {
+    // do something
+    return 127;
+});
diff --git a/tests/baselines/reference/objectLiteralMemberWithoutBlock1.js b/tests/baselines/reference/objectLiteralMemberWithoutBlock1.js
index 2ad13950b14..d6a8579be04 100644
--- a/tests/baselines/reference/objectLiteralMemberWithoutBlock1.js
+++ b/tests/baselines/reference/objectLiteralMemberWithoutBlock1.js
@@ -2,5 +2,4 @@
 var v = { foo(); }
 
 //// [objectLiteralMemberWithoutBlock1.js]
-var v = { foo: function () {
-} };
+var v = { foo: function () { } };
diff --git a/tests/baselines/reference/thisReferencedInFunctionInsideArrowFunction1.js b/tests/baselines/reference/thisReferencedInFunctionInsideArrowFunction1.js
index d6718a56106..77fdc507887 100644
--- a/tests/baselines/reference/thisReferencedInFunctionInsideArrowFunction1.js
+++ b/tests/baselines/reference/thisReferencedInFunctionInsideArrowFunction1.js
@@ -10,7 +10,9 @@ function test()
 //// [thisReferencedInFunctionInsideArrowFunction1.js]
 var foo = function (dummy) { };
 function test() {
-    foo(function () { return function () {
-        return this;
-    }; });
+    foo(function () {
+        return function () {
+            return this;
+        };
+    });
 }