diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index b63e301fbbc..9311aa7cc26 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -104,6 +104,7 @@ namespace ts {
     function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
         let file: SourceFile;
         let options: CompilerOptions;
+        let languageVersion: ScriptTarget;
         let parent: Node;
         let container: Node;
         let blockScopeContainer: Node;
@@ -136,6 +137,7 @@ namespace ts {
         function bindSourceFile(f: SourceFile, opts: CompilerOptions) {
             file = f;
             options = opts;
+            languageVersion = getEmitScriptTarget(options);
             inStrictMode = !!file.externalModuleIndicator;
             classifiableNames = {};
 
@@ -149,6 +151,7 @@ namespace ts {
 
             file = undefined;
             options = undefined;
+            languageVersion = undefined;
             parent = undefined;
             container = undefined;
             blockScopeContainer = undefined;
@@ -1125,6 +1128,35 @@ namespace ts {
             }
         }
 
+        function getStrictModeBlockScopeFunctionDeclarationMessage(node: Node) {
+            // Provide specialized messages to help the user understand why we think they're in
+            // strict mode.
+            if (getContainingClass(node)) {
+                return Diagnostics.Function_declarations_are_not_allowed_inside_blocks_in_strict_mode_when_targeting_ES3_or_ES5_Class_definitions_are_automatically_in_strict_mode;
+            }
+
+            if (file.externalModuleIndicator) {
+                return Diagnostics.Function_declarations_are_not_allowed_inside_blocks_in_strict_mode_when_targeting_ES3_or_ES5_Modules_are_automatically_in_strict_mode;
+            }
+
+            return Diagnostics.Function_declarations_are_not_allowed_inside_blocks_in_strict_mode_when_targeting_ES3_or_ES5;
+        }
+
+        function checkStrictModeFunctionDeclaration(node: FunctionDeclaration) {
+            if (languageVersion < ScriptTarget.ES6) {
+                // Report error if function is not top level function declaration
+                if (blockScopeContainer.kind !== SyntaxKind.SourceFile &&
+                    blockScopeContainer.kind !== SyntaxKind.ModuleDeclaration &&
+                    !isFunctionLike(blockScopeContainer)) {
+                    // We check first if the name is inside class declaration or class expression; if so give explicit message
+                    // otherwise report generic error message.
+                    const errorSpan = getErrorSpanForNode(file, node);
+                    file.bindDiagnostics.push(createFileDiagnostic(file, errorSpan.start, errorSpan.length,
+                        getStrictModeBlockScopeFunctionDeclarationMessage(node)));
+                }
+            }
+        }
+
         function checkStrictModeNumericLiteral(node: LiteralExpression) {
             if (inStrictMode && node.isOctalLiteral) {
                 file.bindDiagnostics.push(createDiagnosticForNode(node, Diagnostics.Octal_literals_are_not_allowed_in_strict_mode));
@@ -1640,7 +1672,13 @@ namespace ts {
             }
 
             checkStrictModeFunctionName(<FunctionDeclaration>node);
-            return declareSymbolAndAddToSymbolTable(<Declaration>node, SymbolFlags.Function, SymbolFlags.FunctionExcludes);
+            if (inStrictMode) {
+                checkStrictModeFunctionDeclaration(node);
+                return bindBlockScopedDeclaration(node, SymbolFlags.Function, SymbolFlags.FunctionExcludes);
+            }
+            else {
+                return declareSymbolAndAddToSymbolTable(<Declaration>node, SymbolFlags.Function, SymbolFlags.FunctionExcludes);
+            }
         }
 
         function bindFunctionExpression(node: FunctionExpression) {
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 793118d008b..b331241660c 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -811,6 +811,18 @@
         "category": "Error",
         "code": 1249
     },
+    "Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.": {
+        "category": "Error",
+        "code": 1250
+    },
+    "Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'. Class definitions are automatically in strict mode.": {
+        "category": "Error",
+        "code": 1251
+    },
+    "Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'. Modules are automatically in strict mode.": {
+        "category": "Error",
+        "code": 1252
+    },
     "'with' statements are not allowed in an async function block.": {
         "category": "Error",
         "code": 1300
diff --git a/src/harness/compilerRunner.ts b/src/harness/compilerRunner.ts
index ea0877c42b2..67d51c14b0f 100644
--- a/src/harness/compilerRunner.ts
+++ b/src/harness/compilerRunner.ts
@@ -256,125 +256,128 @@ class CompilerBaselineRunner extends RunnerBase {
                 }
 
                 // NEWTODO: Type baselines
-                if (result.errors.length === 0) {
-                    // The full walker simulates the types that you would get from doing a full
-                    // compile.  The pull walker simulates the types you get when you just do
-                    // a type query for a random node (like how the LS would do it).  Most of the
-                    // time, these will be the same.  However, occasionally, they can be different.
-                    // Specifically, when the compiler internally depends on symbol IDs to order
-                    // things, then we may see different results because symbols can be created in a
-                    // different order with 'pull' operations, and thus can produce slightly differing
-                    // output.
-                    //
-                    // For example, with a full type check, we may see a type displayed as: number | string
-                    // But with a pull type check, we may see it as:                        string | number
-                    //
-                    // These types are equivalent, but depend on what order the compiler observed
-                    // certain parts of the program.
-
-                    const program = result.program;
-                    const allFiles = toBeCompiled.concat(otherFiles).filter(file => !!program.getSourceFile(file.unitName));
-
-                    const fullWalker = new TypeWriterWalker(program, /*fullTypeCheck*/ true);
-
-                    const fullResults: ts.Map<TypeWriterResult[]> = {};
-                    const pullResults: ts.Map<TypeWriterResult[]> = {};
-
-                    for (const sourceFile of allFiles) {
-                        fullResults[sourceFile.unitName] = fullWalker.getTypeAndSymbols(sourceFile.unitName);
-                        pullResults[sourceFile.unitName] = fullWalker.getTypeAndSymbols(sourceFile.unitName);
-                    }
-
-                    // Produce baselines.  The first gives the types for all expressions.
-                    // The second gives symbols for all identifiers.
-                    let e1: Error, e2: Error;
-                    try {
-                        checkBaseLines(/*isSymbolBaseLine*/ false);
-                    }
-                    catch (e) {
-                        e1 = e;
-                    }
-
-                    try {
-                        checkBaseLines(/*isSymbolBaseLine*/ true);
-                    }
-                    catch (e) {
-                        e2 = e;
-                    }
-
-                    if (e1 || e2) {
-                        throw e1 || e2;
-                    }
-
+                if (result.errors.length !== 0) {
                     return;
+                }
 
-                    function checkBaseLines(isSymbolBaseLine: boolean) {
-                        const fullBaseLine = generateBaseLine(fullResults, isSymbolBaseLine);
-                        const pullBaseLine = generateBaseLine(pullResults, isSymbolBaseLine);
+                // The full walker simulates the types that you would get from doing a full
+                // compile.  The pull walker simulates the types you get when you just do
+                // a type query for a random node (like how the LS would do it).  Most of the
+                // time, these will be the same.  However, occasionally, they can be different.
+                // Specifically, when the compiler internally depends on symbol IDs to order
+                // things, then we may see different results because symbols can be created in a
+                // different order with 'pull' operations, and thus can produce slightly differing
+                // output.
+                //
+                // For example, with a full type check, we may see a type displayed as: number | string
+                // But with a pull type check, we may see it as:                        string | number
+                //
+                // These types are equivalent, but depend on what order the compiler observed
+                // certain parts of the program.
 
-                        const fullExtension = isSymbolBaseLine ? ".symbols" : ".types";
-                        const pullExtension = isSymbolBaseLine ? ".symbols.pull" : ".types.pull";
+                const program = result.program;
+                const allFiles = toBeCompiled.concat(otherFiles).filter(file => !!program.getSourceFile(file.unitName));
 
-                        if (fullBaseLine !== pullBaseLine) {
-                            Harness.Baseline.runBaseline("Correct full information for " + fileName, justName.replace(/\.tsx?/, fullExtension), () => fullBaseLine);
-                            Harness.Baseline.runBaseline("Correct pull information for " + fileName, justName.replace(/\.tsx?/, pullExtension), () => pullBaseLine);
-                        }
-                        else {
-                            Harness.Baseline.runBaseline("Correct information for " + fileName, justName.replace(/\.tsx?/, fullExtension), () => fullBaseLine);
-                        }
+                const fullWalker = new TypeWriterWalker(program, /*fullTypeCheck*/ true);
+
+                const fullResults: ts.Map<TypeWriterResult[]> = {};
+                const pullResults: ts.Map<TypeWriterResult[]> = {};
+
+                for (const sourceFile of allFiles) {
+                    fullResults[sourceFile.unitName] = fullWalker.getTypeAndSymbols(sourceFile.unitName);
+                    pullResults[sourceFile.unitName] = fullWalker.getTypeAndSymbols(sourceFile.unitName);
+                }
+
+                // Produce baselines.  The first gives the types for all expressions.
+                // The second gives symbols for all identifiers.
+                let e1: Error, e2: Error;
+                try {
+                    checkBaseLines(/*isSymbolBaseLine*/ false);
+                }
+                catch (e) {
+                    e1 = e;
+                }
+
+                try {
+                    checkBaseLines(/*isSymbolBaseLine*/ true);
+                }
+                catch (e) {
+                    e2 = e;
+                }
+
+                if (e1 || e2) {
+                    throw e1 || e2;
+                }
+
+                return;
+
+                function checkBaseLines(isSymbolBaseLine: boolean) {
+                    const fullBaseLine = generateBaseLine(fullResults, isSymbolBaseLine);
+                    const pullBaseLine = generateBaseLine(pullResults, isSymbolBaseLine);
+
+                    const fullExtension = isSymbolBaseLine ? ".symbols" : ".types";
+                    const pullExtension = isSymbolBaseLine ? ".symbols.pull" : ".types.pull";
+
+                    if (fullBaseLine !== pullBaseLine) {
+                        Harness.Baseline.runBaseline("Correct full information for " + fileName, justName.replace(/\.tsx?/, fullExtension), () => fullBaseLine);
+                        Harness.Baseline.runBaseline("Correct pull information for " + fileName, justName.replace(/\.tsx?/, pullExtension), () => pullBaseLine);
                     }
-
-                    function generateBaseLine(typeWriterResults: ts.Map<TypeWriterResult[]>, isSymbolBaseline: boolean): string {
-                        const typeLines: string[] = [];
-                        const typeMap: { [fileName: string]: { [lineNum: number]: string[]; } } = {};
-
-                        allFiles.forEach(file => {
-                            const codeLines = file.content.split("\n");
-                            typeWriterResults[file.unitName].forEach(result => {
-                                if (isSymbolBaseline && !result.symbol) {
-                                    return;
-                                }
-
-                                const typeOrSymbolString = isSymbolBaseline ? result.symbol : result.type;
-                                const formattedLine = result.sourceText.replace(/\r?\n/g, "") + " : " + typeOrSymbolString;
-                                if (!typeMap[file.unitName]) {
-                                    typeMap[file.unitName] = {};
-                                }
-
-                                let typeInfo = [formattedLine];
-                                const existingTypeInfo = typeMap[file.unitName][result.line];
-                                if (existingTypeInfo) {
-                                    typeInfo = existingTypeInfo.concat(typeInfo);
-                                }
-                                typeMap[file.unitName][result.line] = typeInfo;
-                            });
-
-                            typeLines.push("=== " + file.unitName + " ===\r\n");
-                            for (let i = 0; i < codeLines.length; i++) {
-                                const currentCodeLine = codeLines[i];
-                                typeLines.push(currentCodeLine + "\r\n");
-                                if (typeMap[file.unitName]) {
-                                    const typeInfo = typeMap[file.unitName][i];
-                                    if (typeInfo) {
-                                        typeInfo.forEach(ty => {
-                                            typeLines.push(">" + ty + "\r\n");
-                                        });
-                                        if (i + 1 < codeLines.length && (codeLines[i + 1].match(/^\s*[{|}]\s*$/) || codeLines[i + 1].trim() === "")) {
-                                        }
-                                        else {
-                                            typeLines.push("\r\n");
-                                        }
-                                    }
-                                }
-                                else {
-                                    typeLines.push("No type information for this code.");
-                                }
-                            }
-                        });
-
-                        return typeLines.join("");
+                    else {
+                        Harness.Baseline.runBaseline("Correct information for " + fileName, justName.replace(/\.tsx?/, fullExtension), () => fullBaseLine);
                     }
                 }
+
+                function generateBaseLine(typeWriterResults: ts.Map<TypeWriterResult[]>, isSymbolBaseline: boolean): string {
+                    const typeLines: string[] = [];
+                    const typeMap: { [fileName: string]: { [lineNum: number]: string[]; } } = {};
+
+                    allFiles.forEach(file => {
+                        const codeLines = file.content.split("\n");
+                        typeWriterResults[file.unitName].forEach(result => {
+                            if (isSymbolBaseline && !result.symbol) {
+                                return;
+                            }
+
+                            const typeOrSymbolString = isSymbolBaseline ? result.symbol : result.type;
+                            const formattedLine = result.sourceText.replace(/\r?\n/g, "") + " : " + typeOrSymbolString;
+                            if (!typeMap[file.unitName]) {
+                                typeMap[file.unitName] = {};
+                            }
+
+                            let typeInfo = [formattedLine];
+                            const existingTypeInfo = typeMap[file.unitName][result.line];
+                            if (existingTypeInfo) {
+                                typeInfo = existingTypeInfo.concat(typeInfo);
+                            }
+                            typeMap[file.unitName][result.line] = typeInfo;
+                        });
+
+                        typeLines.push("=== " + file.unitName + " ===\r\n");
+                        for (let i = 0; i < codeLines.length; i++) {
+                            const currentCodeLine = codeLines[i];
+                            typeLines.push(currentCodeLine + "\r\n");
+                            if (typeMap[file.unitName]) {
+                                const typeInfo = typeMap[file.unitName][i];
+                                if (typeInfo) {
+                                    typeInfo.forEach(ty => {
+                                        typeLines.push(">" + ty + "\r\n");
+                                    });
+                                    if (i + 1 < codeLines.length && (codeLines[i + 1].match(/^\s*[{|}]\s*$/) || codeLines[i + 1].trim() === "")) {
+                                    }
+                                    else {
+                                        typeLines.push("\r\n");
+                                    }
+                                }
+                            }
+                            else {
+                                typeLines.push("No type information for this code.");
+                            }
+                        }
+                    });
+
+                    return typeLines.join("");
+                }
+
             });
         });
     }
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationES5.js b/tests/baselines/reference/blockScopedFunctionDeclarationES5.js
new file mode 100644
index 00000000000..066dd07351c
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationES5.js
@@ -0,0 +1,13 @@
+//// [blockScopedFunctionDeclarationES5.ts]
+if (true) {
+    function foo() { }
+    foo();
+}
+foo();
+
+//// [blockScopedFunctionDeclarationES5.js]
+if (true) {
+    function foo() { }
+    foo();
+}
+foo();
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationES5.symbols b/tests/baselines/reference/blockScopedFunctionDeclarationES5.symbols
new file mode 100644
index 00000000000..5c8f82cf0ff
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationES5.symbols
@@ -0,0 +1,11 @@
+=== tests/cases/compiler/blockScopedFunctionDeclarationES5.ts ===
+if (true) {
+    function foo() { }
+>foo : Symbol(foo, Decl(blockScopedFunctionDeclarationES5.ts, 0, 11))
+
+    foo();
+>foo : Symbol(foo, Decl(blockScopedFunctionDeclarationES5.ts, 0, 11))
+}
+foo();
+>foo : Symbol(foo, Decl(blockScopedFunctionDeclarationES5.ts, 0, 11))
+
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationES5.types b/tests/baselines/reference/blockScopedFunctionDeclarationES5.types
new file mode 100644
index 00000000000..b3c4d9b7d73
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationES5.types
@@ -0,0 +1,15 @@
+=== tests/cases/compiler/blockScopedFunctionDeclarationES5.ts ===
+if (true) {
+>true : boolean
+
+    function foo() { }
+>foo : () => void
+
+    foo();
+>foo() : void
+>foo : () => void
+}
+foo();
+>foo() : void
+>foo : () => void
+
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationES6.js b/tests/baselines/reference/blockScopedFunctionDeclarationES6.js
new file mode 100644
index 00000000000..32450cd66f1
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationES6.js
@@ -0,0 +1,13 @@
+//// [blockScopedFunctionDeclarationES6.ts]
+if (true) {
+    function foo() { }
+    foo();
+}
+foo();
+
+//// [blockScopedFunctionDeclarationES6.js]
+if (true) {
+    function foo() { }
+    foo();
+}
+foo();
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationES6.symbols b/tests/baselines/reference/blockScopedFunctionDeclarationES6.symbols
new file mode 100644
index 00000000000..65fb133b446
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationES6.symbols
@@ -0,0 +1,11 @@
+=== tests/cases/compiler/blockScopedFunctionDeclarationES6.ts ===
+if (true) {
+    function foo() { }
+>foo : Symbol(foo, Decl(blockScopedFunctionDeclarationES6.ts, 0, 11))
+
+    foo();
+>foo : Symbol(foo, Decl(blockScopedFunctionDeclarationES6.ts, 0, 11))
+}
+foo();
+>foo : Symbol(foo, Decl(blockScopedFunctionDeclarationES6.ts, 0, 11))
+
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationES6.types b/tests/baselines/reference/blockScopedFunctionDeclarationES6.types
new file mode 100644
index 00000000000..7ab74feb0ed
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationES6.types
@@ -0,0 +1,15 @@
+=== tests/cases/compiler/blockScopedFunctionDeclarationES6.ts ===
+if (true) {
+>true : boolean
+
+    function foo() { }
+>foo : () => void
+
+    foo();
+>foo() : void
+>foo : () => void
+}
+foo();
+>foo() : void
+>foo : () => void
+
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationInStrictClass.errors.txt b/tests/baselines/reference/blockScopedFunctionDeclarationInStrictClass.errors.txt
new file mode 100644
index 00000000000..efedfd097a6
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationInStrictClass.errors.txt
@@ -0,0 +1,18 @@
+tests/cases/compiler/blockScopedFunctionDeclarationInStrictClass.ts(4,22): error TS1251: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'. Class definitions are automatically in strict mode.
+tests/cases/compiler/blockScopedFunctionDeclarationInStrictClass.ts(7,9): error TS2304: Cannot find name 'foo'.
+
+
+==== tests/cases/compiler/blockScopedFunctionDeclarationInStrictClass.ts (2 errors) ====
+    class c {
+        method() {
+            if (true) {
+                function foo() { }
+                         ~~~
+!!! error TS1251: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'. Class definitions are automatically in strict mode.
+                foo(); // ok
+            }
+            foo(); // not ok
+            ~~~
+!!! error TS2304: Cannot find name 'foo'.
+        }
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationInStrictClass.js b/tests/baselines/reference/blockScopedFunctionDeclarationInStrictClass.js
new file mode 100644
index 00000000000..70a00a95a41
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationInStrictClass.js
@@ -0,0 +1,24 @@
+//// [blockScopedFunctionDeclarationInStrictClass.ts]
+class c {
+    method() {
+        if (true) {
+            function foo() { }
+            foo(); // ok
+        }
+        foo(); // not ok
+    }
+}
+
+//// [blockScopedFunctionDeclarationInStrictClass.js]
+var c = (function () {
+    function c() {
+    }
+    c.prototype.method = function () {
+        if (true) {
+            function foo() { }
+            foo(); // ok
+        }
+        foo(); // not ok
+    };
+    return c;
+}());
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationInStrictModule.errors.txt b/tests/baselines/reference/blockScopedFunctionDeclarationInStrictModule.errors.txt
new file mode 100644
index 00000000000..3f53ef24b58
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationInStrictModule.errors.txt
@@ -0,0 +1,15 @@
+tests/cases/compiler/blockScopedFunctionDeclarationInStrictModule.ts(2,14): error TS1252: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'. Modules are automatically in strict mode.
+tests/cases/compiler/blockScopedFunctionDeclarationInStrictModule.ts(6,10): error TS2304: Cannot find name 'foo'.
+
+
+==== tests/cases/compiler/blockScopedFunctionDeclarationInStrictModule.ts (2 errors) ====
+    if (true) {
+        function foo() { }
+                 ~~~
+!!! error TS1252: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'. Modules are automatically in strict mode.
+        foo(); // ok
+    }
+    
+    export = foo; // not ok
+             ~~~
+!!! error TS2304: Cannot find name 'foo'.
\ No newline at end of file
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationInStrictModule.js b/tests/baselines/reference/blockScopedFunctionDeclarationInStrictModule.js
new file mode 100644
index 00000000000..cd118733e3c
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationInStrictModule.js
@@ -0,0 +1,16 @@
+//// [blockScopedFunctionDeclarationInStrictModule.ts]
+if (true) {
+    function foo() { }
+    foo(); // ok
+}
+
+export = foo; // not ok
+
+//// [blockScopedFunctionDeclarationInStrictModule.js]
+define(["require", "exports"], function (require, exports) {
+    "use strict";
+    if (true) {
+        function foo() { }
+        foo(); // ok
+    }
+});
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationStrictES5.errors.txt b/tests/baselines/reference/blockScopedFunctionDeclarationStrictES5.errors.txt
new file mode 100644
index 00000000000..f945d0eacbf
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationStrictES5.errors.txt
@@ -0,0 +1,15 @@
+tests/cases/compiler/blockScopedFunctionDeclarationStrictES5.ts(3,14): error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+tests/cases/compiler/blockScopedFunctionDeclarationStrictES5.ts(6,1): error TS2304: Cannot find name 'foo'.
+
+
+==== tests/cases/compiler/blockScopedFunctionDeclarationStrictES5.ts (2 errors) ====
+    "use strict";
+    if (true) {
+        function foo() { } // Error to declare function in block scope
+                 ~~~
+!!! error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+        foo(); // This call should be ok
+    }
+    foo(); // Error to find name foo
+    ~~~
+!!! error TS2304: Cannot find name 'foo'.
\ No newline at end of file
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationStrictES5.js b/tests/baselines/reference/blockScopedFunctionDeclarationStrictES5.js
new file mode 100644
index 00000000000..f0926cadf39
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationStrictES5.js
@@ -0,0 +1,15 @@
+//// [blockScopedFunctionDeclarationStrictES5.ts]
+"use strict";
+if (true) {
+    function foo() { } // Error to declare function in block scope
+    foo(); // This call should be ok
+}
+foo(); // Error to find name foo
+
+//// [blockScopedFunctionDeclarationStrictES5.js]
+"use strict";
+if (true) {
+    function foo() { } // Error to declare function in block scope
+    foo(); // This call should be ok
+}
+foo(); // Error to find name foo
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationStrictES6.errors.txt b/tests/baselines/reference/blockScopedFunctionDeclarationStrictES6.errors.txt
new file mode 100644
index 00000000000..6772a29926b
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationStrictES6.errors.txt
@@ -0,0 +1,12 @@
+tests/cases/compiler/blockScopedFunctionDeclarationStrictES6.ts(6,1): error TS2304: Cannot find name 'foo'.
+
+
+==== tests/cases/compiler/blockScopedFunctionDeclarationStrictES6.ts (1 errors) ====
+    "use strict";
+    if (true) {
+        function foo() { } // Allowed to declare block scope function
+        foo(); // This call should be ok
+    }
+    foo(); // Cannot find name since foo is block scoped
+    ~~~
+!!! error TS2304: Cannot find name 'foo'.
\ No newline at end of file
diff --git a/tests/baselines/reference/blockScopedFunctionDeclarationStrictES6.js b/tests/baselines/reference/blockScopedFunctionDeclarationStrictES6.js
new file mode 100644
index 00000000000..0a1b263875b
--- /dev/null
+++ b/tests/baselines/reference/blockScopedFunctionDeclarationStrictES6.js
@@ -0,0 +1,15 @@
+//// [blockScopedFunctionDeclarationStrictES6.ts]
+"use strict";
+if (true) {
+    function foo() { } // Allowed to declare block scope function
+    foo(); // This call should be ok
+}
+foo(); // Cannot find name since foo is block scoped
+
+//// [blockScopedFunctionDeclarationStrictES6.js]
+"use strict";
+if (true) {
+    function foo() { } // Allowed to declare block scope function
+    foo(); // This call should be ok
+}
+foo(); // Cannot find name since foo is block scoped
diff --git a/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES5.errors.txt b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES5.errors.txt
new file mode 100644
index 00000000000..3efa85d1cc7
--- /dev/null
+++ b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES5.errors.txt
@@ -0,0 +1,37 @@
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts(3,18): error TS2393: Duplicate function implementation.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts(5,9): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts(8,18): error TS2393: Duplicate function implementation.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts(10,9): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts(12,5): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts(16,1): error TS2346: Supplied parameters do not match any signature of call target.
+
+
+==== tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts (6 errors) ====
+    function foo(a: number) {
+        if (a === 1) {
+            function foo() { } // duplicate function
+                     ~~~
+!!! error TS2393: Duplicate function implementation.
+            foo(); 
+            foo(10); // not ok
+            ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        }
+        else {
+            function foo() { } // duplicate function
+                     ~~~
+!!! error TS2393: Duplicate function implementation.
+            foo(); 
+            foo(10); // not ok
+            ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        }
+        foo(10); // not ok
+        ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        foo(); 
+    }
+    foo(10);
+    foo(); // not ok - needs number
+    ~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
\ No newline at end of file
diff --git a/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES5.js b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES5.js
new file mode 100644
index 00000000000..4c7721f9b43
--- /dev/null
+++ b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES5.js
@@ -0,0 +1,35 @@
+//// [blockScopedSameNameFunctionDeclarationES5.ts]
+function foo(a: number) {
+    if (a === 1) {
+        function foo() { } // duplicate function
+        foo(); 
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } // duplicate function
+        foo(); 
+        foo(10); // not ok
+    }
+    foo(10); // not ok
+    foo(); 
+}
+foo(10);
+foo(); // not ok - needs number
+
+//// [blockScopedSameNameFunctionDeclarationES5.js]
+function foo(a) {
+    if (a === 1) {
+        function foo() { } // duplicate function
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } // duplicate function
+        foo();
+        foo(10); // not ok
+    }
+    foo(10); // not ok
+    foo();
+}
+foo(10);
+foo(); // not ok - needs number
diff --git a/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES6.errors.txt b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES6.errors.txt
new file mode 100644
index 00000000000..5d15278f098
--- /dev/null
+++ b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES6.errors.txt
@@ -0,0 +1,37 @@
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts(3,18): error TS2393: Duplicate function implementation.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts(5,9): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts(8,18): error TS2393: Duplicate function implementation.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts(10,9): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts(12,5): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts(16,1): error TS2346: Supplied parameters do not match any signature of call target.
+
+
+==== tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts (6 errors) ====
+    function foo(a: number) {
+        if (a === 10) {
+            function foo() { } // duplicate
+                     ~~~
+!!! error TS2393: Duplicate function implementation.
+            foo();
+            foo(10); // not ok
+            ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        }
+        else {
+            function foo() { } // duplicate
+                     ~~~
+!!! error TS2393: Duplicate function implementation.
+            foo();
+            foo(10);// not ok
+            ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        }
+        foo(10); // not ok
+        ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        foo(); 
+    }
+    foo(10);
+    foo(); // not ok - needs number
+    ~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
\ No newline at end of file
diff --git a/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES6.js b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES6.js
new file mode 100644
index 00000000000..c793b74c60a
--- /dev/null
+++ b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationES6.js
@@ -0,0 +1,35 @@
+//// [blockScopedSameNameFunctionDeclarationES6.ts]
+function foo(a: number) {
+    if (a === 10) {
+        function foo() { } // duplicate
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } // duplicate
+        foo();
+        foo(10);// not ok
+    }
+    foo(10); // not ok
+    foo(); 
+}
+foo(10);
+foo(); // not ok - needs number
+
+//// [blockScopedSameNameFunctionDeclarationES6.js]
+function foo(a) {
+    if (a === 10) {
+        function foo() { } // duplicate
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } // duplicate
+        foo();
+        foo(10); // not ok
+    }
+    foo(10); // not ok
+    foo();
+}
+foo(10);
+foo(); // not ok - needs number
diff --git a/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES5.errors.txt b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES5.errors.txt
new file mode 100644
index 00000000000..36ce2d8c488
--- /dev/null
+++ b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES5.errors.txt
@@ -0,0 +1,38 @@
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts(4,18): error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts(6,9): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts(9,18): error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts(11,9): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts(14,5): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts(17,1): error TS2346: Supplied parameters do not match any signature of call target.
+
+
+==== tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts (6 errors) ====
+    "use strict";
+    function foo(a: number) {
+        if (a === 1) {
+            function foo() { } // Error to declare function in block scope
+                     ~~~
+!!! error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+            foo();
+            foo(10); // not ok
+            ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        }
+        else {
+            function foo() { } // Error to declare function in block scope
+                     ~~~
+!!! error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+            foo();
+            foo(10); // not ok
+            ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        }
+        foo(10);
+        foo(); // not ok - needs number
+        ~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+    }
+    foo(10);
+    foo(); // not ok - needs number
+    ~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
\ No newline at end of file
diff --git a/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES5.js b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES5.js
new file mode 100644
index 00000000000..b51be0493cd
--- /dev/null
+++ b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES5.js
@@ -0,0 +1,37 @@
+//// [blockScopedSameNameFunctionDeclarationStrictES5.ts]
+"use strict";
+function foo(a: number) {
+    if (a === 1) {
+        function foo() { } // Error to declare function in block scope
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } // Error to declare function in block scope
+        foo();
+        foo(10); // not ok
+    }
+    foo(10);
+    foo(); // not ok - needs number
+}
+foo(10);
+foo(); // not ok - needs number
+
+//// [blockScopedSameNameFunctionDeclarationStrictES5.js]
+"use strict";
+function foo(a) {
+    if (a === 1) {
+        function foo() { } // Error to declare function in block scope
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } // Error to declare function in block scope
+        foo();
+        foo(10); // not ok
+    }
+    foo(10);
+    foo(); // not ok - needs number
+}
+foo(10);
+foo(); // not ok - needs number
diff --git a/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES6.errors.txt b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES6.errors.txt
new file mode 100644
index 00000000000..7b8834c5594
--- /dev/null
+++ b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES6.errors.txt
@@ -0,0 +1,32 @@
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES6.ts(6,9): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES6.ts(11,9): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES6.ts(14,5): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES6.ts(17,1): error TS2346: Supplied parameters do not match any signature of call target.
+
+
+==== tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES6.ts (4 errors) ====
+    "use strict";
+    function foo(a: number) {
+        if (a === 10) {
+            function foo() { }
+            foo();
+            foo(10); // not ok
+            ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        }
+        else {
+            function foo() { } 
+            foo();
+            foo(10); // not ok
+            ~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+        }
+        foo(10);
+        foo(); // not ok
+        ~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+    }
+    foo(10);
+    foo(); // not ok - needs number
+    ~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
\ No newline at end of file
diff --git a/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES6.js b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES6.js
new file mode 100644
index 00000000000..863df86c031
--- /dev/null
+++ b/tests/baselines/reference/blockScopedSameNameFunctionDeclarationStrictES6.js
@@ -0,0 +1,37 @@
+//// [blockScopedSameNameFunctionDeclarationStrictES6.ts]
+"use strict";
+function foo(a: number) {
+    if (a === 10) {
+        function foo() { }
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } 
+        foo();
+        foo(10); // not ok
+    }
+    foo(10);
+    foo(); // not ok
+}
+foo(10);
+foo(); // not ok - needs number
+
+//// [blockScopedSameNameFunctionDeclarationStrictES6.js]
+"use strict";
+function foo(a) {
+    if (a === 10) {
+        function foo() { }
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { }
+        foo();
+        foo(10); // not ok
+    }
+    foo(10);
+    foo(); // not ok
+}
+foo(10);
+foo(); // not ok - needs number
diff --git a/tests/baselines/reference/downlevelLetConst18.errors.txt b/tests/baselines/reference/downlevelLetConst18.errors.txt
new file mode 100644
index 00000000000..5b91498f173
--- /dev/null
+++ b/tests/baselines/reference/downlevelLetConst18.errors.txt
@@ -0,0 +1,40 @@
+tests/cases/compiler/downlevelLetConst18.ts(5,14): error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+tests/cases/compiler/downlevelLetConst18.ts(9,14): error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+
+
+==== tests/cases/compiler/downlevelLetConst18.ts (2 errors) ====
+    
+    'use strict'
+    
+    for (let x; ;) {
+        function foo() { x };
+                 ~~~
+!!! error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+    }
+    
+    for (let x; ;) {
+        function foo1() { x };
+                 ~~~~
+!!! error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+    }
+    
+    for (let x; ;) {
+        (() => { x })();
+    }
+    
+    for (const x = 1; ;) {
+        (() => { x })();
+    }
+    
+    for (let x; ;) {
+        ({ foo() { x }})
+    }
+    
+    for (let x; ;) {
+        ({ get foo() { return x } })
+    }
+    
+    for (let x; ;) {
+        ({ set foo(v) { x } })
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/downlevelLetConst18.symbols b/tests/baselines/reference/downlevelLetConst18.symbols
deleted file mode 100644
index a1df0dc6ae9..00000000000
--- a/tests/baselines/reference/downlevelLetConst18.symbols
+++ /dev/null
@@ -1,59 +0,0 @@
-=== tests/cases/compiler/downlevelLetConst18.ts ===
-
-'use strict'
-
-for (let x; ;) {
->x : Symbol(x, Decl(downlevelLetConst18.ts, 3, 8))
-
-    function foo() { x };
->foo : Symbol(foo, Decl(downlevelLetConst18.ts, 3, 16))
->x : Symbol(x, Decl(downlevelLetConst18.ts, 3, 8))
-}
-
-for (let x; ;) {
->x : Symbol(x, Decl(downlevelLetConst18.ts, 7, 8))
-
-    function foo1() { x };
->foo1 : Symbol(foo1, Decl(downlevelLetConst18.ts, 7, 16))
->x : Symbol(x, Decl(downlevelLetConst18.ts, 7, 8))
-}
-
-for (let x; ;) {
->x : Symbol(x, Decl(downlevelLetConst18.ts, 11, 8))
-
-    (() => { x })();
->x : Symbol(x, Decl(downlevelLetConst18.ts, 11, 8))
-}
-
-for (const x = 1; ;) {
->x : Symbol(x, Decl(downlevelLetConst18.ts, 15, 10))
-
-    (() => { x })();
->x : Symbol(x, Decl(downlevelLetConst18.ts, 15, 10))
-}
-
-for (let x; ;) {
->x : Symbol(x, Decl(downlevelLetConst18.ts, 19, 8))
-
-    ({ foo() { x }})
->foo : Symbol(foo, Decl(downlevelLetConst18.ts, 20, 6))
->x : Symbol(x, Decl(downlevelLetConst18.ts, 19, 8))
-}
-
-for (let x; ;) {
->x : Symbol(x, Decl(downlevelLetConst18.ts, 23, 8))
-
-    ({ get foo() { return x } })
->foo : Symbol(foo, Decl(downlevelLetConst18.ts, 24, 6))
->x : Symbol(x, Decl(downlevelLetConst18.ts, 23, 8))
-}
-
-for (let x; ;) {
->x : Symbol(x, Decl(downlevelLetConst18.ts, 27, 8))
-
-    ({ set foo(v) { x } })
->foo : Symbol(foo, Decl(downlevelLetConst18.ts, 28, 6))
->v : Symbol(v, Decl(downlevelLetConst18.ts, 28, 15))
->x : Symbol(x, Decl(downlevelLetConst18.ts, 27, 8))
-}
-
diff --git a/tests/baselines/reference/downlevelLetConst18.types b/tests/baselines/reference/downlevelLetConst18.types
deleted file mode 100644
index 1f7be616124..00000000000
--- a/tests/baselines/reference/downlevelLetConst18.types
+++ /dev/null
@@ -1,73 +0,0 @@
-=== tests/cases/compiler/downlevelLetConst18.ts ===
-
-'use strict'
->'use strict' : string
-
-for (let x; ;) {
->x : any
-
-    function foo() { x };
->foo : () => void
->x : any
-}
-
-for (let x; ;) {
->x : any
-
-    function foo1() { x };
->foo1 : () => void
->x : any
-}
-
-for (let x; ;) {
->x : any
-
-    (() => { x })();
->(() => { x })() : void
->(() => { x }) : () => void
->() => { x } : () => void
->x : any
-}
-
-for (const x = 1; ;) {
->x : number
->1 : number
-
-    (() => { x })();
->(() => { x })() : void
->(() => { x }) : () => void
->() => { x } : () => void
->x : number
-}
-
-for (let x; ;) {
->x : any
-
-    ({ foo() { x }})
->({ foo() { x }}) : { foo(): void; }
->{ foo() { x }} : { foo(): void; }
->foo : () => void
->x : any
-}
-
-for (let x; ;) {
->x : any
-
-    ({ get foo() { return x } })
->({ get foo() { return x } }) : { readonly foo: any; }
->{ get foo() { return x } } : { readonly foo: any; }
->foo : any
->x : any
-}
-
-for (let x; ;) {
->x : any
-
-    ({ set foo(v) { x } })
->({ set foo(v) { x } }) : { foo: any; }
->{ set foo(v) { x } } : { foo: any; }
->foo : any
->v : any
->x : any
-}
-
diff --git a/tests/baselines/reference/downlevelLetConst19.errors.txt b/tests/baselines/reference/downlevelLetConst19.errors.txt
new file mode 100644
index 00000000000..ef8583347bd
--- /dev/null
+++ b/tests/baselines/reference/downlevelLetConst19.errors.txt
@@ -0,0 +1,25 @@
+tests/cases/compiler/downlevelLetConst19.ts(9,14): error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+
+
+==== tests/cases/compiler/downlevelLetConst19.ts (1 errors) ====
+    'use strict'
+    declare function use(a: any);
+    var x;
+    function a() {
+      {
+        let x;
+        use(x);
+    
+        function b() {
+                 ~
+!!! error TS1250: Function declarations are not allowed inside blocks in strict mode when targeting 'ES3' or 'ES5'.
+            {
+                let x;
+                use(x);
+            }
+            use(x);
+        }
+      }
+      use(x)
+    }
+    use(x)
\ No newline at end of file
diff --git a/tests/baselines/reference/downlevelLetConst19.symbols b/tests/baselines/reference/downlevelLetConst19.symbols
deleted file mode 100644
index 9ed23e43447..00000000000
--- a/tests/baselines/reference/downlevelLetConst19.symbols
+++ /dev/null
@@ -1,42 +0,0 @@
-=== tests/cases/compiler/downlevelLetConst19.ts ===
-'use strict'
-declare function use(a: any);
->use : Symbol(use, Decl(downlevelLetConst19.ts, 0, 12))
->a : Symbol(a, Decl(downlevelLetConst19.ts, 1, 21))
-
-var x;
->x : Symbol(x, Decl(downlevelLetConst19.ts, 2, 3))
-
-function a() {
->a : Symbol(a, Decl(downlevelLetConst19.ts, 2, 6))
-  {
-    let x;
->x : Symbol(x, Decl(downlevelLetConst19.ts, 5, 7))
-
-    use(x);
->use : Symbol(use, Decl(downlevelLetConst19.ts, 0, 12))
->x : Symbol(x, Decl(downlevelLetConst19.ts, 5, 7))
-
-    function b() {
->b : Symbol(b, Decl(downlevelLetConst19.ts, 6, 11))
-        {
-            let x;
->x : Symbol(x, Decl(downlevelLetConst19.ts, 10, 15))
-
-            use(x);
->use : Symbol(use, Decl(downlevelLetConst19.ts, 0, 12))
->x : Symbol(x, Decl(downlevelLetConst19.ts, 10, 15))
-        }
-        use(x);
->use : Symbol(use, Decl(downlevelLetConst19.ts, 0, 12))
->x : Symbol(x, Decl(downlevelLetConst19.ts, 5, 7))
-    }
-  }
-  use(x)
->use : Symbol(use, Decl(downlevelLetConst19.ts, 0, 12))
->x : Symbol(x, Decl(downlevelLetConst19.ts, 2, 3))
-}
-use(x)
->use : Symbol(use, Decl(downlevelLetConst19.ts, 0, 12))
->x : Symbol(x, Decl(downlevelLetConst19.ts, 2, 3))
-
diff --git a/tests/baselines/reference/downlevelLetConst19.types b/tests/baselines/reference/downlevelLetConst19.types
deleted file mode 100644
index 687033c195a..00000000000
--- a/tests/baselines/reference/downlevelLetConst19.types
+++ /dev/null
@@ -1,49 +0,0 @@
-=== tests/cases/compiler/downlevelLetConst19.ts ===
-'use strict'
->'use strict' : string
-
-declare function use(a: any);
->use : (a: any) => any
->a : any
-
-var x;
->x : any
-
-function a() {
->a : () => void
-  {
-    let x;
->x : any
-
-    use(x);
->use(x) : any
->use : (a: any) => any
->x : any
-
-    function b() {
->b : () => void
-        {
-            let x;
->x : any
-
-            use(x);
->use(x) : any
->use : (a: any) => any
->x : any
-        }
-        use(x);
->use(x) : any
->use : (a: any) => any
->x : any
-    }
-  }
-  use(x)
->use(x) : any
->use : (a: any) => any
->x : any
-}
-use(x)
->use(x) : any
->use : (a: any) => any
->x : any
-
diff --git a/tests/cases/compiler/blockScopedFunctionDeclarationES5.ts b/tests/cases/compiler/blockScopedFunctionDeclarationES5.ts
new file mode 100644
index 00000000000..dbb725361a0
--- /dev/null
+++ b/tests/cases/compiler/blockScopedFunctionDeclarationES5.ts
@@ -0,0 +1,6 @@
+// @target: ES5
+if (true) {
+    function foo() { }
+    foo();
+}
+foo();
\ No newline at end of file
diff --git a/tests/cases/compiler/blockScopedFunctionDeclarationES6.ts b/tests/cases/compiler/blockScopedFunctionDeclarationES6.ts
new file mode 100644
index 00000000000..fd0e678b806
--- /dev/null
+++ b/tests/cases/compiler/blockScopedFunctionDeclarationES6.ts
@@ -0,0 +1,6 @@
+// @target: ES6
+if (true) {
+    function foo() { }
+    foo();
+}
+foo();
\ No newline at end of file
diff --git a/tests/cases/compiler/blockScopedFunctionDeclarationInStrictClass.ts b/tests/cases/compiler/blockScopedFunctionDeclarationInStrictClass.ts
new file mode 100644
index 00000000000..48d83e6ad87
--- /dev/null
+++ b/tests/cases/compiler/blockScopedFunctionDeclarationInStrictClass.ts
@@ -0,0 +1,10 @@
+// @target: ES5
+class c {
+    method() {
+        if (true) {
+            function foo() { }
+            foo(); // ok
+        }
+        foo(); // not ok
+    }
+}
\ No newline at end of file
diff --git a/tests/cases/compiler/blockScopedFunctionDeclarationInStrictModule.ts b/tests/cases/compiler/blockScopedFunctionDeclarationInStrictModule.ts
new file mode 100644
index 00000000000..48c68770620
--- /dev/null
+++ b/tests/cases/compiler/blockScopedFunctionDeclarationInStrictModule.ts
@@ -0,0 +1,8 @@
+// @target: ES5
+// @module: amd
+if (true) {
+    function foo() { }
+    foo(); // ok
+}
+
+export = foo; // not ok
\ No newline at end of file
diff --git a/tests/cases/compiler/blockScopedFunctionDeclarationStrictES5.ts b/tests/cases/compiler/blockScopedFunctionDeclarationStrictES5.ts
new file mode 100644
index 00000000000..c5035e1130c
--- /dev/null
+++ b/tests/cases/compiler/blockScopedFunctionDeclarationStrictES5.ts
@@ -0,0 +1,7 @@
+// @target: ES5
+"use strict";
+if (true) {
+    function foo() { } // Error to declare function in block scope
+    foo(); // This call should be ok
+}
+foo(); // Error to find name foo
\ No newline at end of file
diff --git a/tests/cases/compiler/blockScopedFunctionDeclarationStrictES6.ts b/tests/cases/compiler/blockScopedFunctionDeclarationStrictES6.ts
new file mode 100644
index 00000000000..043890add06
--- /dev/null
+++ b/tests/cases/compiler/blockScopedFunctionDeclarationStrictES6.ts
@@ -0,0 +1,7 @@
+// @target: ES6
+"use strict";
+if (true) {
+    function foo() { } // Allowed to declare block scope function
+    foo(); // This call should be ok
+}
+foo(); // Cannot find name since foo is block scoped
\ No newline at end of file
diff --git a/tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts b/tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts
new file mode 100644
index 00000000000..a5e10d19af2
--- /dev/null
+++ b/tests/cases/compiler/blockScopedSameNameFunctionDeclarationES5.ts
@@ -0,0 +1,17 @@
+// @target: ES5
+function foo(a: number) {
+    if (a === 1) {
+        function foo() { } // duplicate function
+        foo(); 
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } // duplicate function
+        foo(); 
+        foo(10); // not ok
+    }
+    foo(10); // not ok
+    foo(); 
+}
+foo(10);
+foo(); // not ok - needs number
\ No newline at end of file
diff --git a/tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts b/tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts
new file mode 100644
index 00000000000..c97e50964e7
--- /dev/null
+++ b/tests/cases/compiler/blockScopedSameNameFunctionDeclarationES6.ts
@@ -0,0 +1,17 @@
+// @target: ES6
+function foo(a: number) {
+    if (a === 10) {
+        function foo() { } // duplicate
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } // duplicate
+        foo();
+        foo(10);// not ok
+    }
+    foo(10); // not ok
+    foo(); 
+}
+foo(10);
+foo(); // not ok - needs number
\ No newline at end of file
diff --git a/tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts b/tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts
new file mode 100644
index 00000000000..a0073c75d43
--- /dev/null
+++ b/tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES5.ts
@@ -0,0 +1,18 @@
+// @target: ES5
+"use strict";
+function foo(a: number) {
+    if (a === 1) {
+        function foo() { } // Error to declare function in block scope
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } // Error to declare function in block scope
+        foo();
+        foo(10); // not ok
+    }
+    foo(10);
+    foo(); // not ok - needs number
+}
+foo(10);
+foo(); // not ok - needs number
\ No newline at end of file
diff --git a/tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES6.ts b/tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES6.ts
new file mode 100644
index 00000000000..34d73a05201
--- /dev/null
+++ b/tests/cases/compiler/blockScopedSameNameFunctionDeclarationStrictES6.ts
@@ -0,0 +1,18 @@
+// @target: ES6
+"use strict";
+function foo(a: number) {
+    if (a === 10) {
+        function foo() { }
+        foo();
+        foo(10); // not ok
+    }
+    else {
+        function foo() { } 
+        foo();
+        foo(10); // not ok
+    }
+    foo(10);
+    foo(); // not ok
+}
+foo(10);
+foo(); // not ok - needs number
\ No newline at end of file