diff --git a/tsc/internal/bundled/libs/lib.es2015.collection.d.ts b/tsc/internal/bundled/libs/lib.es2015.collection.d.ts
index 225e918b76477..55399ad8ec1f1 100644
--- a/tsc/internal/bundled/libs/lib.es2015.collection.d.ts
+++ b/tsc/internal/bundled/libs/lib.es2015.collection.d.ts
@@ -49,6 +49,7 @@ interface Map<K, V> {
 interface MapConstructor {
     new (): Map<any, any>;
     new <K, V>(entries?: readonly (readonly [K, V])[] | null): Map<K, V>;
+    new <KV extends readonly [any, any]>(entries?: readonly KV[] | null): Map<KV[0], KV[1]>;
     readonly prototype: Map<any, any>;
 }
 declare var Map: MapConstructor;
diff --git a/tsc/internal/bundled/libs/lib.es2015.iterable.d.ts b/tsc/internal/bundled/libs/lib.es2015.iterable.d.ts
index 7396a53feb8cf..650139576ddac 100644
--- a/tsc/internal/bundled/libs/lib.es2015.iterable.d.ts
+++ b/tsc/internal/bundled/libs/lib.es2015.iterable.d.ts
@@ -179,6 +179,7 @@ interface ReadonlyMap<K, V> {
 interface MapConstructor {
     new (): Map<any, any>;
     new <K, V>(iterable?: Iterable<readonly [K, V]> | null): Map<K, V>;
+    new <KV extends readonly [any, any]>(iterable?: Iterable<KV> | null): Map<KV[0], KV[1]>;
 }
 
 interface WeakMap<K extends WeakKey, V> {}
diff --git a/tsc/testdata/baselines/reference/compiler/newMap.errors.txt b/tsc/testdata/baselines/reference/compiler/newMap.errors.txt
index ac5cce1f5ed80..ec31222ec6a3e 100644
--- a/tsc/testdata/baselines/reference/compiler/newMap.errors.txt
+++ b/tsc/testdata/baselines/reference/compiler/newMap.errors.txt
@@ -1,9 +1,9 @@
-newMap.ts(1,9): error TS2743: No overload expects 1 type arguments, but overloads do exist that expect either 0 or 2 type arguments.
+newMap.ts(1,9): error TS2344: Type 'string' does not satisfy the constraint 'readonly [any, any]'.
 
 
 ==== newMap.ts (1 errors) ====
     new Map<string>();
             ~~~~~~
-!!! error TS2743: No overload expects 1 type arguments, but overloads do exist that expect either 0 or 2 type arguments.
+!!! error TS2344: Type 'string' does not satisfy the constraint 'readonly [any, any]'.
     new WeakMap<object>();
     
\ No newline at end of file
diff --git a/tsc/testdata/baselines/reference/conformance/for-of39.errors.txt b/tsc/testdata/baselines/reference/conformance/for-of39.errors.txt
deleted file mode 100644
index 9b25b5eb78a78..0000000000000
--- a/tsc/testdata/baselines/reference/conformance/for-of39.errors.txt
+++ /dev/null
@@ -1,16 +0,0 @@
-for-of39.ts(1,25): error TS2769: No overload matches this call.
-  The last overload gave the following error.
-    Type 'boolean' is not assignable to type 'number'.
-
-
-==== for-of39.ts (1 errors) ====
-    var map = new Map([["", true], ["", 0]]);
-                            ~~~~
-!!! error TS2769: No overload matches this call.
-!!! error TS2769:   The last overload gave the following error.
-!!! error TS2769:     Type 'boolean' is not assignable to type 'number'.
-!!! related TS2771 lib.es2015.collection.d.ts:--:--: The last overload is declared here.
-    for (var [k, v] of map) {
-        k;
-        v;
-    }
\ No newline at end of file
diff --git a/tsc/testdata/baselines/reference/conformance/for-of39.types b/tsc/testdata/baselines/reference/conformance/for-of39.types
index 220f0474230f1..f42a6f133cdde 100644
--- a/tsc/testdata/baselines/reference/conformance/for-of39.types
+++ b/tsc/testdata/baselines/reference/conformance/for-of39.types
@@ -2,11 +2,11 @@
 
 === for-of39.ts ===
 var map = new Map([["", true], ["", 0]]);
->map : Map<string, number>
->new Map([["", true], ["", 0]]) : Map<string, number>
+>map : Map<string, number | boolean>
+>new Map([["", true], ["", 0]]) : Map<string, number | boolean>
 >Map : MapConstructor
->[["", true], ["", 0]] : ([string, number] | [string, boolean])[]
->["", true] : [string, boolean]
+>[["", true], ["", 0]] : ([string, number] | [string, true])[]
+>["", true] : [string, true]
 >"" : ""
 >true : true
 >["", 0] : [string, number]
@@ -15,12 +15,12 @@ var map = new Map([["", true], ["", 0]]);
 
 for (var [k, v] of map) {
 >k : string
->v : number
->map : Map<string, number>
+>v : number | boolean
+>map : Map<string, number | boolean>
 
     k;
 >k : string
 
     v;
->v : number
+>v : number | boolean
 }
diff --git a/tsc/testdata/baselines/reference/conformance/iterableArrayPattern28.errors.txt b/tsc/testdata/baselines/reference/conformance/iterableArrayPattern28.errors.txt
index 23d0eab3af01e..9fd23f7e97209 100644
--- a/tsc/testdata/baselines/reference/conformance/iterableArrayPattern28.errors.txt
+++ b/tsc/testdata/baselines/reference/conformance/iterableArrayPattern28.errors.txt
@@ -1,13 +1,14 @@
-iterableArrayPattern28.ts(2,52): error TS2769: No overload matches this call.
-  The last overload gave the following error.
-    Type 'boolean' is not assignable to type 'number'.
+iterableArrayPattern28.ts(2,21): error TS2345: Argument of type '[string, number | boolean]' is not assignable to parameter of type '[string, number]'.
+  Type at position 1 in source is not compatible with type at position 1 in target.
+    Type 'number | boolean' is not assignable to type 'number'.
+      Type 'boolean' is not assignable to type 'number'.
 
 
 ==== iterableArrayPattern28.ts (1 errors) ====
     function takeFirstTwoEntries(...[[k1, v1], [k2, v2]]: [string, number][]) { }
     takeFirstTwoEntries(...new Map([["", 0], ["hello", true]]));
-                                                       ~~~~
-!!! error TS2769: No overload matches this call.
-!!! error TS2769:   The last overload gave the following error.
-!!! error TS2769:     Type 'boolean' is not assignable to type 'number'.
-!!! related TS2771 lib.es2015.collection.d.ts:--:--: The last overload is declared here.
\ No newline at end of file
+                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2345: Argument of type '[string, number | boolean]' is not assignable to parameter of type '[string, number]'.
+!!! error TS2345:   Type at position 1 in source is not compatible with type at position 1 in target.
+!!! error TS2345:     Type 'number | boolean' is not assignable to type 'number'.
+!!! error TS2345:       Type 'boolean' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tsc/testdata/baselines/reference/conformance/iterableArrayPattern28.types b/tsc/testdata/baselines/reference/conformance/iterableArrayPattern28.types
index 2d836c6eab74d..b833ab983fece 100644
--- a/tsc/testdata/baselines/reference/conformance/iterableArrayPattern28.types
+++ b/tsc/testdata/baselines/reference/conformance/iterableArrayPattern28.types
@@ -11,14 +11,14 @@ function takeFirstTwoEntries(...[[k1, v1], [k2, v2]]: [string, number][]) { }
 takeFirstTwoEntries(...new Map([["", 0], ["hello", true]]));
 >takeFirstTwoEntries(...new Map([["", 0], ["hello", true]])) : void
 >takeFirstTwoEntries : (...[[k1, v1], [k2, v2]]: [string, number][]) => void
->...new Map([["", 0], ["hello", true]]) : [string, number]
->new Map([["", 0], ["hello", true]]) : Map<string, number>
+>...new Map([["", 0], ["hello", true]]) : [string, number | boolean]
+>new Map([["", 0], ["hello", true]]) : Map<string, number | boolean>
 >Map : MapConstructor
->[["", 0], ["hello", true]] : ([string, number] | [string, boolean])[]
+>[["", 0], ["hello", true]] : ([string, number] | [string, true])[]
 >["", 0] : [string, number]
 >"" : ""
 >0 : 0
->["hello", true] : [string, boolean]
+>["hello", true] : [string, true]
 >"hello" : "hello"
 >true : true
 
diff --git a/tsc/testdata/baselines/reference/conformance/new-Map1.js b/tsc/testdata/baselines/reference/conformance/new-Map1.js
new file mode 100644
index 0000000000000..53c665e92be81
--- /dev/null
+++ b/tsc/testdata/baselines/reference/conformance/new-Map1.js
@@ -0,0 +1,46 @@
+//// [tests/cases/conformance/es6/mapConstruction/new-Map1.ts] ////
+
+//// [new-Map1.ts]
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-628802102
+const sample: Map<number | string, number> = new Map([[1, 1], ["yes", 1]]);
+
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-750412755
+function test(_a: Map<string | number, boolean>) {}
+test(new Map([["test" ,true] ,[1 ,false]]))
+
+// https://github.com/microsoft/TypeScript/issues/33611#issue-498858215
+const M1 = new Map([
+	['k', {a: 1, b: 'asd'}],
+	['k', {a: 2, b: 'asd'}],
+]);
+const M2 = new Map([
+	...M1,
+	['k', {a: 1}],
+]);
+
+// Additional cases
+const m1 = new Map([['num', 123], ['str', 'val1']]);
+const m2 = new Map([['num', 456], ['str', 'val2']] as const);
+const m3 = new Map([['num' as const, 456], ['str' as const, 'val2']]);
+
+
+//// [new-Map1.js]
+"use strict";
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-628802102
+const sample = new Map([[1, 1], ["yes", 1]]);
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-750412755
+function test(_a) { }
+test(new Map([["test", true], [1, false]]));
+// https://github.com/microsoft/TypeScript/issues/33611#issue-498858215
+const M1 = new Map([
+    ['k', { a: 1, b: 'asd' }],
+    ['k', { a: 2, b: 'asd' }],
+]);
+const M2 = new Map([
+    ...M1,
+    ['k', { a: 1 }],
+]);
+// Additional cases
+const m1 = new Map([['num', 123], ['str', 'val1']]);
+const m2 = new Map([['num', 456], ['str', 'val2']]);
+const m3 = new Map([['num', 456], ['str', 'val2']]);
diff --git a/tsc/testdata/baselines/reference/conformance/new-Map1.symbols b/tsc/testdata/baselines/reference/conformance/new-Map1.symbols
new file mode 100644
index 0000000000000..74a3315139ed7
--- /dev/null
+++ b/tsc/testdata/baselines/reference/conformance/new-Map1.symbols
@@ -0,0 +1,61 @@
+//// [tests/cases/conformance/es6/mapConstruction/new-Map1.ts] ////
+
+=== new-Map1.ts ===
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-628802102
+const sample: Map<number | string, number> = new Map([[1, 1], ["yes", 1]]);
+>sample : Symbol(sample, Decl(new-Map1.ts, 1, 5))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-750412755
+function test(_a: Map<string | number, boolean>) {}
+>test : Symbol(test, Decl(new-Map1.ts, 1, 75))
+>_a : Symbol(_a, Decl(new-Map1.ts, 4, 14))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+
+test(new Map([["test" ,true] ,[1 ,false]]))
+>test : Symbol(test, Decl(new-Map1.ts, 1, 75))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+
+// https://github.com/microsoft/TypeScript/issues/33611#issue-498858215
+const M1 = new Map([
+>M1 : Symbol(M1, Decl(new-Map1.ts, 8, 5))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+
+	['k', {a: 1, b: 'asd'}],
+>a : Symbol(a, Decl(new-Map1.ts, 9, 8))
+>b : Symbol(b, Decl(new-Map1.ts, 9, 13))
+
+	['k', {a: 2, b: 'asd'}],
+>a : Symbol(a, Decl(new-Map1.ts, 10, 8))
+>b : Symbol(b, Decl(new-Map1.ts, 10, 13))
+
+]);
+const M2 = new Map([
+>M2 : Symbol(M2, Decl(new-Map1.ts, 12, 5))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+
+	...M1,
+>M1 : Symbol(M1, Decl(new-Map1.ts, 8, 5))
+
+	['k', {a: 1}],
+>a : Symbol(a, Decl(new-Map1.ts, 14, 8))
+
+]);
+
+// Additional cases
+const m1 = new Map([['num', 123], ['str', 'val1']]);
+>m1 : Symbol(m1, Decl(new-Map1.ts, 18, 5))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+
+const m2 = new Map([['num', 456], ['str', 'val2']] as const);
+>m2 : Symbol(m2, Decl(new-Map1.ts, 19, 5))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+>const : Symbol(const)
+
+const m3 = new Map([['num' as const, 456], ['str' as const, 'val2']]);
+>m3 : Symbol(m3, Decl(new-Map1.ts, 20, 5))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+>const : Symbol(const)
+>const : Symbol(const)
+
diff --git a/tsc/testdata/baselines/reference/conformance/new-Map1.types b/tsc/testdata/baselines/reference/conformance/new-Map1.types
new file mode 100644
index 0000000000000..dcc7d379b50ec
--- /dev/null
+++ b/tsc/testdata/baselines/reference/conformance/new-Map1.types
@@ -0,0 +1,119 @@
+//// [tests/cases/conformance/es6/mapConstruction/new-Map1.ts] ////
+
+=== new-Map1.ts ===
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-628802102
+const sample: Map<number | string, number> = new Map([[1, 1], ["yes", 1]]);
+>sample : Map<string | number, number>
+>new Map([[1, 1], ["yes", 1]]) : Map<string | number, number>
+>Map : MapConstructor
+>[[1, 1], ["yes", 1]] : ([string, number] | [number, number])[]
+>[1, 1] : [number, number]
+>1 : 1
+>1 : 1
+>["yes", 1] : [string, number]
+>"yes" : "yes"
+>1 : 1
+
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-750412755
+function test(_a: Map<string | number, boolean>) {}
+>test : (_a: Map<string | number, boolean>) => void
+>_a : Map<string | number, boolean>
+
+test(new Map([["test" ,true] ,[1 ,false]]))
+>test(new Map([["test" ,true] ,[1 ,false]])) : void
+>test : (_a: Map<string | number, boolean>) => void
+>new Map([["test" ,true] ,[1 ,false]]) : Map<string | number, boolean>
+>Map : MapConstructor
+>[["test" ,true] ,[1 ,false]] : ([string, true] | [number, false])[]
+>["test" ,true] : [string, true]
+>"test" : "test"
+>true : true
+>[1 ,false] : [number, false]
+>1 : 1
+>false : false
+
+// https://github.com/microsoft/TypeScript/issues/33611#issue-498858215
+const M1 = new Map([
+>M1 : Map<string, { a: number; b: string; }>
+>new Map([	['k', {a: 1, b: 'asd'}],	['k', {a: 2, b: 'asd'}],]) : Map<string, { a: number; b: string; }>
+>Map : MapConstructor
+>[	['k', {a: 1, b: 'asd'}],	['k', {a: 2, b: 'asd'}],] : [string, { a: number; b: string; }][]
+
+	['k', {a: 1, b: 'asd'}],
+>['k', {a: 1, b: 'asd'}] : [string, { a: number; b: string; }]
+>'k' : "k"
+>{a: 1, b: 'asd'} : { a: number; b: string; }
+>a : number
+>1 : 1
+>b : string
+>'asd' : "asd"
+
+	['k', {a: 2, b: 'asd'}],
+>['k', {a: 2, b: 'asd'}] : [string, { a: number; b: string; }]
+>'k' : "k"
+>{a: 2, b: 'asd'} : { a: number; b: string; }
+>a : number
+>2 : 2
+>b : string
+>'asd' : "asd"
+
+]);
+const M2 = new Map([
+>M2 : Map<string, { a: number; b: string; } | { a: number; }>
+>new Map([	...M1,	['k', {a: 1}],]) : Map<string, { a: number; b: string; } | { a: number; }>
+>Map : MapConstructor
+>[	...M1,	['k', {a: 1}],] : ([string, { a: number; b: string; }] | [string, { a: number; }])[]
+
+	...M1,
+>...M1 : [string, { a: number; b: string; }]
+>M1 : Map<string, { a: number; b: string; }>
+
+	['k', {a: 1}],
+>['k', {a: 1}] : [string, { a: number; }]
+>'k' : "k"
+>{a: 1} : { a: number; }
+>a : number
+>1 : 1
+
+]);
+
+// Additional cases
+const m1 = new Map([['num', 123], ['str', 'val1']]);
+>m1 : Map<string, string | number>
+>new Map([['num', 123], ['str', 'val1']]) : Map<string, string | number>
+>Map : MapConstructor
+>[['num', 123], ['str', 'val1']] : ([string, string] | [string, number])[]
+>['num', 123] : [string, number]
+>'num' : "num"
+>123 : 123
+>['str', 'val1'] : [string, string]
+>'str' : "str"
+>'val1' : "val1"
+
+const m2 = new Map([['num', 456], ['str', 'val2']] as const);
+>m2 : Map<"num" | "str", "val2" | 456>
+>new Map([['num', 456], ['str', 'val2']] as const) : Map<"num" | "str", "val2" | 456>
+>Map : MapConstructor
+>[['num', 456], ['str', 'val2']] as const : readonly [readonly ["num", 456], readonly ["str", "val2"]]
+>[['num', 456], ['str', 'val2']] : readonly [readonly ["num", 456], readonly ["str", "val2"]]
+>['num', 456] : readonly ["num", 456]
+>'num' : "num"
+>456 : 456
+>['str', 'val2'] : readonly ["str", "val2"]
+>'str' : "str"
+>'val2' : "val2"
+
+const m3 = new Map([['num' as const, 456], ['str' as const, 'val2']]);
+>m3 : Map<"num" | "str", string | number>
+>new Map([['num' as const, 456], ['str' as const, 'val2']]) : Map<"num" | "str", string | number>
+>Map : MapConstructor
+>[['num' as const, 456], ['str' as const, 'val2']] : (["num", number] | ["str", string])[]
+>['num' as const, 456] : ["num", number]
+>'num' as const : "num"
+>'num' : "num"
+>456 : 456
+>['str' as const, 'val2'] : ["str", string]
+>'str' as const : "str"
+>'str' : "str"
+>'val2' : "val2"
+
diff --git a/tsc/testdata/baselines/reference/conformance/new-Map2.errors.txt b/tsc/testdata/baselines/reference/conformance/new-Map2.errors.txt
new file mode 100644
index 0000000000000..54a1fa3dea806
--- /dev/null
+++ b/tsc/testdata/baselines/reference/conformance/new-Map2.errors.txt
@@ -0,0 +1,17 @@
+new-Map2.ts(6,7): error TS7034: Variable 'a3' implicitly has type 'any[]' in some locations where its type cannot be determined.
+new-Map2.ts(7,20): error TS7005: Variable 'a3' implicitly has an 'any[]' type.
+
+
+==== new-Map2.ts (2 errors) ====
+    const m1 = new Map([]);
+    
+    const a2: any[] = [];
+    const m2 = new Map(a2);
+    
+    const a3 = [];
+          ~~
+!!! error TS7034: Variable 'a3' implicitly has type 'any[]' in some locations where its type cannot be determined.
+    const m3 = new Map(a3);
+                       ~~
+!!! error TS7005: Variable 'a3' implicitly has an 'any[]' type.
+    
\ No newline at end of file
diff --git a/tsc/testdata/baselines/reference/conformance/new-Map2.js b/tsc/testdata/baselines/reference/conformance/new-Map2.js
new file mode 100644
index 0000000000000..3139f2d165031
--- /dev/null
+++ b/tsc/testdata/baselines/reference/conformance/new-Map2.js
@@ -0,0 +1,19 @@
+//// [tests/cases/conformance/es6/mapConstruction/new-Map2.ts] ////
+
+//// [new-Map2.ts]
+const m1 = new Map([]);
+
+const a2: any[] = [];
+const m2 = new Map(a2);
+
+const a3 = [];
+const m3 = new Map(a3);
+
+
+//// [new-Map2.js]
+"use strict";
+const m1 = new Map([]);
+const a2 = [];
+const m2 = new Map(a2);
+const a3 = [];
+const m3 = new Map(a3);
diff --git a/tsc/testdata/baselines/reference/conformance/new-Map2.symbols b/tsc/testdata/baselines/reference/conformance/new-Map2.symbols
new file mode 100644
index 0000000000000..2a082d8006ee6
--- /dev/null
+++ b/tsc/testdata/baselines/reference/conformance/new-Map2.symbols
@@ -0,0 +1,23 @@
+//// [tests/cases/conformance/es6/mapConstruction/new-Map2.ts] ////
+
+=== new-Map2.ts ===
+const m1 = new Map([]);
+>m1 : Symbol(m1, Decl(new-Map2.ts, 0, 5))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+
+const a2: any[] = [];
+>a2 : Symbol(a2, Decl(new-Map2.ts, 2, 5))
+
+const m2 = new Map(a2);
+>m2 : Symbol(m2, Decl(new-Map2.ts, 3, 5))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+>a2 : Symbol(a2, Decl(new-Map2.ts, 2, 5))
+
+const a3 = [];
+>a3 : Symbol(a3, Decl(new-Map2.ts, 5, 5))
+
+const m3 = new Map(a3);
+>m3 : Symbol(m3, Decl(new-Map2.ts, 6, 5))
+>Map : Symbol(Map, Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2026.collection.d.ts, --, --))
+>a3 : Symbol(a3, Decl(new-Map2.ts, 5, 5))
+
diff --git a/tsc/testdata/baselines/reference/conformance/new-Map2.types b/tsc/testdata/baselines/reference/conformance/new-Map2.types
new file mode 100644
index 0000000000000..81aad9abbe2c7
--- /dev/null
+++ b/tsc/testdata/baselines/reference/conformance/new-Map2.types
@@ -0,0 +1,29 @@
+//// [tests/cases/conformance/es6/mapConstruction/new-Map2.ts] ////
+
+=== new-Map2.ts ===
+const m1 = new Map([]);
+>m1 : Map<unknown, unknown>
+>new Map([]) : Map<unknown, unknown>
+>Map : MapConstructor
+>[] : never[]
+
+const a2: any[] = [];
+>a2 : any[]
+>[] : never[]
+
+const m2 = new Map(a2);
+>m2 : Map<any, any>
+>new Map(a2) : Map<any, any>
+>Map : MapConstructor
+>a2 : any[]
+
+const a3 = [];
+>a3 : any[]
+>[] : never[]
+
+const m3 = new Map(a3);
+>m3 : Map<any, any>
+>new Map(a3) : Map<any, any>
+>Map : MapConstructor
+>a3 : any[]
+
diff --git a/tsc/testdata/tests/cases/conformance/es6/mapConstruction/new-Map1.ts b/tsc/testdata/tests/cases/conformance/es6/mapConstruction/new-Map1.ts
new file mode 100644
index 0000000000000..d97e848cbc0ef
--- /dev/null
+++ b/tsc/testdata/tests/cases/conformance/es6/mapConstruction/new-Map1.ts
@@ -0,0 +1,21 @@
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-628802102
+const sample: Map<number | string, number> = new Map([[1, 1], ["yes", 1]]);
+
+// https://github.com/microsoft/TypeScript/issues/37527#issuecomment-750412755
+function test(_a: Map<string | number, boolean>) {}
+test(new Map([["test" ,true] ,[1 ,false]]))
+
+// https://github.com/microsoft/TypeScript/issues/33611#issue-498858215
+const M1 = new Map([
+	['k', {a: 1, b: 'asd'}],
+	['k', {a: 2, b: 'asd'}],
+]);
+const M2 = new Map([
+	...M1,
+	['k', {a: 1}],
+]);
+
+// Additional cases
+const m1 = new Map([['num', 123], ['str', 'val1']]);
+const m2 = new Map([['num', 456], ['str', 'val2']] as const);
+const m3 = new Map([['num' as const, 456], ['str' as const, 'val2']]);
diff --git a/tsc/testdata/tests/cases/conformance/es6/mapConstruction/new-Map2.ts b/tsc/testdata/tests/cases/conformance/es6/mapConstruction/new-Map2.ts
new file mode 100644
index 0000000000000..1a07769dd67ce
--- /dev/null
+++ b/tsc/testdata/tests/cases/conformance/es6/mapConstruction/new-Map2.ts
@@ -0,0 +1,7 @@
+const m1 = new Map([]);
+
+const a2: any[] = [];
+const m2 = new Map(a2);
+
+const a3 = [];
+const m3 = new Map(a3);