diff --git a/test/IDE/complete_decl_attribute.swift b/test/IDE/complete_decl_attribute.swift
index f1d2579eab5..99444a4ee51 100644
--- a/test/IDE/complete_decl_attribute.swift
+++ b/test/IDE/complete_decl_attribute.swift
@@ -92,6 +92,7 @@ actor MyGlobalActor {
 // KEYWORD2-NEXT:             Keyword/None:                       noDerivative[#Func Attribute#]; name=noDerivative
 // KEYWORD2-NEXT:             Keyword/None:                       Sendable[#Func Attribute#]; name=Sendable
 // KEYWORD2-NEXT:             Keyword/None:                       preconcurrency[#Func Attribute#]; name=preconcurrency
+// KEYWORD2-NEXT:             Keyword/None:                       backDeployed[#Func Attribute#]; name=backDeployed
 // KEYWORD2-NOT:              Keyword
 // KEYWORD2-DAG:              Decl[Struct]/CurrModule:            MyStruct[#MyStruct#]; name=MyStruct
 // KEYWORD2-DAG:              Decl[Struct]/CurrModule:            MyPropertyWrapper[#MyPropertyWrapper#]; name=MyPropertyWrapper
@@ -241,6 +242,7 @@ struct _S {
 // ON_METHOD-DAG: Keyword/None:                       Sendable[#Func Attribute#]; name=Sendable
 // ON_METHOD-DAG: Keyword/None:                       noDerivative[#Func Attribute#]; name=noDerivative
 // ON_METHOD-DAG: Keyword/None:                       preconcurrency[#Func Attribute#]; name=preconcurrency
+// ON_METHOD-DAG: Keyword/None:                       backDeployed[#Func Attribute#]; name=backDeployed
 // ON_METHOD-NOT: Keyword
 // ON_METHOD-DAG: Decl[Struct]/CurrModule:            MyStruct[#MyStruct#]; name=MyStruct
 // ON_METHOD-DAG: Decl[Struct]/CurrModule:            MyPropertyWrapper[#MyPropertyWrapper#]; name=MyPropertyWrapper
diff --git a/test/IRGen/weak_import_back_deployed_attr.swift b/test/IRGen/weak_import_back_deployed_attr.swift
index 27493c8315a..71c5977163f 100644
--- a/test/IRGen/weak_import_back_deployed_attr.swift
+++ b/test/IRGen/weak_import_back_deployed_attr.swift
@@ -10,7 +10,7 @@
 //--- Library.swift
 
 @available(macOS 10.50, *)
-@_backDeploy(before: macOS 10.60)
+@backDeployed(before: macOS 10.60)
 public func backDeployedFunc() {}
 
 //--- Client.swift
diff --git a/test/ModuleInterface/back-deployed-attr.swift b/test/ModuleInterface/back-deployed-attr.swift
index 23f28b323aa..8a4573a3177 100644
--- a/test/ModuleInterface/back-deployed-attr.swift
+++ b/test/ModuleInterface/back-deployed-attr.swift
@@ -6,36 +6,37 @@
 // RUN: %FileCheck %s < %t/Test.swiftinterface
 
 public struct TopLevelStruct {
+  // TODO: Print `@backDeployed` in swiftinterfaces (rdar://104920183)
   // CHECK: @_backDeploy(before: macOS 12.0)
   // CHECK: public func backDeployedFunc_SinglePlatform() -> Swift.Int { return 42 }
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func backDeployedFunc_SinglePlatform() -> Int { return 42 }
   
   // CHECK: @_backDeploy(before: macOS 12.0, iOS 15.0)
   // CHECK: public func backDeployedFunc_MultiPlatform() -> Swift.Int { return 43 }
-  @_backDeploy(before: macOS 12.0, iOS 15.0)
+  @backDeployed(before: macOS 12.0, iOS 15.0)
   public func backDeployedFunc_MultiPlatform() -> Int { return 43 }
 
   // CHECK: @_backDeploy(before: macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0)
   // CHECK: public func backDeployedFunc_MultiPlatformSeparate() -> Swift.Int { return 43 }
-  @_backDeploy(before: macOS 12.0)
-  @_backDeploy(before: iOS 15.0)
-  @_backDeploy(before: watchOS 8.0)
-  @_backDeploy(before: tvOS 15.0)
+  @backDeployed(before: macOS 12.0)
+  @backDeployed(before: iOS 15.0)
+  @backDeployed(before: watchOS 8.0)
+  @backDeployed(before: tvOS 15.0)
   public func backDeployedFunc_MultiPlatformSeparate() -> Int { return 43 }
 
   // CHECK: @_backDeploy(before: macOS 12.0)
   // CHECK: public var backDeployedComputedProperty: Swift.Int {
   // CHECK:   get { 44 }
   // CHECK: }
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public var backDeployedComputedProperty: Int { 44 }
 
   // CHECK: @_backDeploy(before: macOS 12.0)
   // CHECK: public var backDeployedPropertyWithAccessors: Swift.Int {
   // CHECK:   get { 45 }
   // CHECK: }
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public var backDeployedPropertyWithAccessors: Int {
     get { 45 }
   }
@@ -44,7 +45,7 @@ public struct TopLevelStruct {
   // CHECK: public subscript(index: Swift.Int) -> Swift.Int {
   // CHECK:   get { 46 }
   // CHECK: }
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public subscript(index: Int) -> Int {
     get { 46 }
   }
@@ -52,17 +53,17 @@ public struct TopLevelStruct {
 
 // CHECK: @_backDeploy(before: macOS 12.0)
 // CHECK: public func backDeployTopLevelFunc1() -> Swift.Int { return 47 }
-@_backDeploy(before: macOS 12.0)
+@backDeployed(before: macOS 12.0)
 public func backDeployTopLevelFunc1() -> Int { return 47 }
 
 // MARK: - Availability macros
 
 // CHECK: @_backDeploy(before: macOS 12.1)
 // CHECK: public func backDeployTopLevelFunc2() -> Swift.Int { return 48 }
-@_backDeploy(before: _macOS12_1)
+@backDeployed(before: _macOS12_1)
 public func backDeployTopLevelFunc2() -> Int { return 48 }
 
 // CHECK: @_backDeploy(before: macOS 12.1, iOS 15.1)
 // CHECK: public func backDeployTopLevelFunc3() -> Swift.Int { return 49 }
-@_backDeploy(before: _myProject 1.0)
+@backDeployed(before: _myProject 1.0)
 public func backDeployTopLevelFunc3() -> Int { return 49 }
diff --git a/test/SILGen/back_deployed_attr.swift b/test/SILGen/back_deployed_attr.swift
index 427e23dba2e..d325e397aca 100644
--- a/test/SILGen/back_deployed_attr.swift
+++ b/test/SILGen/back_deployed_attr.swift
@@ -6,13 +6,13 @@
 
 // REQUIRES: OS=macosx
 
-@_backDeploy(before: macOS 10.52)
+@backDeployed(before: macOS 10.52)
 public func someFunc() {}
 
 public struct S<T> {
   @usableFromInline var _x: T
 
-  @_backDeploy(before: macOS 10.52)
+  @backDeployed(before: macOS 10.52)
   public var x: T {
     get { _x }
     set { _x = newValue }
@@ -59,7 +59,7 @@ func aeicCaller(_ s: inout S<Z>) {
 }
 
 // CHECK-LABEL: sil non_abi [serialized] [ossa] @$s11back_deploy0A14DeployedCalleryyAA1SVyAA1ZVGzFTwB
-@_backDeploy(before: macOS 10.52)
+@backDeployed(before: macOS 10.52)
 public func backDeployedCaller(_ s: inout S<Z>) {
   // CHECK: function_ref @$s11back_deploy8someFuncyyFTwb : $@convention(thin) () -> ()
   someFunc()
diff --git a/test/SILGen/back_deployed_attr_accessor.swift b/test/SILGen/back_deployed_attr_accessor.swift
index cc1e7dce756..d4ed992ff93 100644
--- a/test/SILGen/back_deployed_attr_accessor.swift
+++ b/test/SILGen/back_deployed_attr_accessor.swift
@@ -35,7 +35,7 @@ public struct TopLevelStruct {
 
   // -- Original definition of TopLevelStruct.property.getter
   // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy14TopLevelStructV8propertyACvg : $@convention(method) (TopLevelStruct) -> TopLevelStruct
-  @_backDeploy(before: macOS 10.52)
+  @backDeployed(before: macOS 10.52)
   public var property: TopLevelStruct { self }
 }
 
diff --git a/test/SILGen/back_deployed_attr_accessor_coroutine.swift b/test/SILGen/back_deployed_attr_accessor_coroutine.swift
index 8b0df940de4..740c25a96cb 100644
--- a/test/SILGen/back_deployed_attr_accessor_coroutine.swift
+++ b/test/SILGen/back_deployed_attr_accessor_coroutine.swift
@@ -62,7 +62,7 @@ public struct TopLevelStruct {
 
   // -- Original definition of TopLevelStruct.property.read
   // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy14TopLevelStructV8propertyACvr : $@yield_once @convention(method) (TopLevelStruct) -> @yields TopLevelStruct
-  @_backDeploy(before: macOS 10.52)
+  @backDeployed(before: macOS 10.52)
   public var property: TopLevelStruct {
     _read { yield self }
   }
diff --git a/test/SILGen/back_deployed_attr_async_func.swift b/test/SILGen/back_deployed_attr_async_func.swift
index c3c45ec83da..10162e7ff41 100644
--- a/test/SILGen/back_deployed_attr_async_func.swift
+++ b/test/SILGen/back_deployed_attr_async_func.swift
@@ -43,7 +43,7 @@
 // -- Original definition of trivialFunc()
 // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy9asyncFuncyyYaF : $@convention(thin) @async () -> ()
 @available(macOS 10.51, *)
-@_backDeploy(before: macOS 10.52)
+@backDeployed(before: macOS 10.52)
 public func asyncFunc() async {
   await otherFunc()
 }
diff --git a/test/SILGen/back_deployed_attr_func.swift b/test/SILGen/back_deployed_attr_func.swift
index a1aeef5e8c7..1896b9d834a 100644
--- a/test/SILGen/back_deployed_attr_func.swift
+++ b/test/SILGen/back_deployed_attr_func.swift
@@ -36,7 +36,7 @@
 
 // -- Original definition of trivialFunc()
 // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy11trivialFuncyyF : $@convention(thin) () -> ()
-@_backDeploy(before: macOS 10.52)
+@backDeployed(before: macOS 10.52)
 public func trivialFunc() {}
 
 // -- Fallback definition of isNumber(_:)
@@ -70,7 +70,7 @@ public func trivialFunc() {}
 
 // -- Original definition of isNumber(_:)
 // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy8isNumberySbSiF : $@convention(thin) (Int) -> Bool
-@_backDeploy(before: macOS 10.52)
+@backDeployed(before: macOS 10.52)
 public func isNumber(_ x: Int) -> Bool {
   return true
 }
diff --git a/test/SILGen/back_deployed_attr_generic_func.swift b/test/SILGen/back_deployed_attr_generic_func.swift
index ebb0c0e6768..62d8dfef81c 100644
--- a/test/SILGen/back_deployed_attr_generic_func.swift
+++ b/test/SILGen/back_deployed_attr_generic_func.swift
@@ -37,7 +37,7 @@
 
 // -- Original definition of genericFunc(_:)
 // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy11genericFuncyxxlF : $@convention(thin) <T> (@in_guaranteed T) -> @out T
-@_backDeploy(before: macOS 10.52)
+@backDeployed(before: macOS 10.52)
 public func genericFunc<T>(_ t: T) -> T {
   return t
 }
@@ -76,7 +76,7 @@ public func genericFunc<T>(_ t: T) -> T {
 
 // -- Original definition of genericFuncWithOwnedParam(_:)
 // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy25genericFuncWithOwnedParamyyxnlF : $@convention(thin) <T> (@in T) -> ()
-@_backDeploy(before: macOS 10.52)
+@backDeployed(before: macOS 10.52)
 public func genericFuncWithOwnedParam<T>(_ t: __owned T) { }
 
 struct S {}
diff --git a/test/SILGen/back_deployed_attr_struct_init.swift b/test/SILGen/back_deployed_attr_struct_init.swift
index f240dcb25c6..13827f86b1e 100644
--- a/test/SILGen/back_deployed_attr_struct_init.swift
+++ b/test/SILGen/back_deployed_attr_struct_init.swift
@@ -56,7 +56,7 @@ public struct TopLevelStruct<T> {
   // -- Original definition of TopLevelStruct.init(_:)
   // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy14TopLevelStructVyACyxGxcfC : $@convention(method) <T> (@in T, @thin TopLevelStruct<T>.Type) -> @out TopLevelStruct<T>
   @available(macOS 10.51, *)
-  @_backDeploy(before: macOS 10.52)
+  @backDeployed(before: macOS 10.52)
   public init(_ t: T) {
     self.t = t
   }
diff --git a/test/SILGen/back_deployed_attr_struct_method.swift b/test/SILGen/back_deployed_attr_struct_method.swift
index cdf473a1793..60da3fc9f2e 100644
--- a/test/SILGen/back_deployed_attr_struct_method.swift
+++ b/test/SILGen/back_deployed_attr_struct_method.swift
@@ -37,7 +37,7 @@ public struct TopLevelStruct {
 
   // -- Original definition of TopLevelStruct.trivialMethod()
   // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy14TopLevelStructV13trivialMethodyyF : $@convention(method) (TopLevelStruct) -> ()
-  @_backDeploy(before: macOS 10.52)
+  @backDeployed(before: macOS 10.52)
   public func trivialMethod() {}
 }
 
diff --git a/test/SILGen/back_deployed_attr_throwing_func.swift b/test/SILGen/back_deployed_attr_throwing_func.swift
index 45480b99bc6..c71d418b952 100644
--- a/test/SILGen/back_deployed_attr_throwing_func.swift
+++ b/test/SILGen/back_deployed_attr_throwing_func.swift
@@ -49,7 +49,7 @@
 
 // -- Original definition of throwingFunc()
 // CHECK-LABEL: sil [available 10.52] [ossa] @$s11back_deploy12throwingFuncyyKF : $@convention(thin) () -> @error any Error
-@_backDeploy(before: macOS 10.52)
+@backDeployed(before: macOS 10.52)
 public func throwingFunc() throws {}
 
 // CHECK-LABEL: sil hidden [ossa] @$s11back_deploy6calleryyKF : $@convention(thin) () -> @error any Error
diff --git a/test/SILGen/opaque_values_silgen.swift b/test/SILGen/opaque_values_silgen.swift
index faaa1cba2a9..66bef215904 100644
--- a/test/SILGen/opaque_values_silgen.swift
+++ b/test/SILGen/opaque_values_silgen.swift
@@ -643,5 +643,5 @@ func giveKeyPathString() {
 // CHECK-NOT: {{bb[0-9]+}}({{%[^,]+}} : @owned $τ_0_0):
 // CHECK-LABEL: } // end sil function '$s20opaque_values_silgen29backDeployingReturningGenericyxxKlFTwb'
 @available(SwiftStdlib 5.1, *)
-@_backDeploy(before: SwiftStdlib 5.8)
+@backDeployed(before: SwiftStdlib 5.8)
 public func backDeployingReturningGeneric<T>(_ t: T) throws -> T { t }
diff --git a/test/Sema/availability_define.swift b/test/Sema/availability_define.swift
index 8e7d4eab454..095a1fe283f 100644
--- a/test/Sema/availability_define.swift
+++ b/test/Sema/availability_define.swift
@@ -96,15 +96,15 @@ public func forbidMacrosInInlinableCode1() {
   }
 }
 
-@_backDeploy(before: _iOS9Aligned)
+@backDeployed(before: _iOS9Aligned)
 public func forbidMacrosInInlinableCode2() {
-  if #available(_iOS9Aligned, *) { } // expected-error {{availability macro cannot be used in a '@_backDeploy' function}}
-  if #available(_iOS9, _macOS10_11, *) { } // expected-error {{availability macro cannot be used in a '@_backDeploy' function}}
-  if #available(iOS 9.0, _macOS10_11, tvOS 9.0, *) { } // expected-error {{availability macro cannot be used in a '@_backDeploy' function}}
-  if #unavailable(_iOS9Aligned) { } // expected-error {{availability macro cannot be used in a '@_backDeploy' function}}
-  if #unavailable(_iOS9, _macOS10_11) { } // expected-error {{availability macro cannot be used in a '@_backDeploy' function}}
-  if #unavailable(iOS 9.0, _macOS10_11, tvOS 9.0) { } // expected-error {{availability macro cannot be used in a '@_backDeploy' function}}
+  if #available(_iOS9Aligned, *) { } // expected-error {{availability macro cannot be used in a '@backDeployed' function}}
+  if #available(_iOS9, _macOS10_11, *) { } // expected-error {{availability macro cannot be used in a '@backDeployed' function}}
+  if #available(iOS 9.0, _macOS10_11, tvOS 9.0, *) { } // expected-error {{availability macro cannot be used in a '@backDeployed' function}}
+  if #unavailable(_iOS9Aligned) { } // expected-error {{availability macro cannot be used in a '@backDeployed' function}}
+  if #unavailable(_iOS9, _macOS10_11) { } // expected-error {{availability macro cannot be used in a '@backDeployed' function}}
+  if #unavailable(iOS 9.0, _macOS10_11, tvOS 9.0) { } // expected-error {{availability macro cannot be used in a '@backDeployed' function}}
   doIt {
-    if #available(_iOS9Aligned, *) { } // expected-error {{availability macro cannot be used in a '@_backDeploy' function}}
+    if #available(_iOS9Aligned, *) { } // expected-error {{availability macro cannot be used in a '@backDeployed' function}}
   }
 }
diff --git a/test/Serialization/back-deployed-attr-skip-noninlinable-function-bodies.swift b/test/Serialization/back-deployed-attr-skip-noninlinable-function-bodies.swift
index c65d0b16a40..bf6d3804d64 100644
--- a/test/Serialization/back-deployed-attr-skip-noninlinable-function-bodies.swift
+++ b/test/Serialization/back-deployed-attr-skip-noninlinable-function-bodies.swift
@@ -1,4 +1,4 @@
 // RUN: %target-swift-frontend -parse-as-library -enable-library-evolution -emit-module -module-name Test -experimental-skip-non-inlinable-function-bodies %s
 
-@_backDeploy(before: SwiftStdlib 5.7)
+@backDeployed(before: SwiftStdlib 5.7)
 public func foo() {}
diff --git a/test/attr/Inputs/BackDeployHelper.swift b/test/attr/Inputs/BackDeployHelper.swift
index f587a865d59..c049a199c61 100644
--- a/test/attr/Inputs/BackDeployHelper.swift
+++ b/test/attr/Inputs/BackDeployHelper.swift
@@ -94,20 +94,20 @@ extension ReferenceIntArray: Countable {
 #if !STRIP_V2_APIS
 
 @available(BackDeploy 1.0, *)
-@_backDeploy(before: BackDeploy 2.0)
+@backDeployed(before: BackDeploy 2.0)
 public func trivial() {
   testPrint(handle: #dsohandle, "trivial")
 }
 
 @available(BackDeploy 1.0, *)
-@_backDeploy(before: BackDeploy 2.0)
+@backDeployed(before: BackDeploy 2.0)
 public func pleaseThrow(_ shouldThrow: Bool) throws -> Bool {
   if shouldThrow { throw BadError.bad }
   return !shouldThrow
 }
 
 @available(BackDeploy 1.0, *)
-@_backDeploy(before: BackDeploy 2.0)
+@backDeployed(before: BackDeploy 2.0)
 public func genericAppend<T: Appendable>(
   _ a: inout T,
   _ x: __owned T.Element
@@ -116,37 +116,37 @@ public func genericAppend<T: Appendable>(
 }
 
 @available(BackDeploy 1.0, *)
-@_backDeploy(before: BackDeploy 2.0)
+@backDeployed(before: BackDeploy 2.0)
 public func existentialCount(_ c: any Countable) -> Int {
   c.count
 }
 
 extension IntArray {
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public var values: [Int] { _values }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public init() { self.init([]) }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public func print() {
-    // Tests recursive @_backDeploy since `Array.print()` is also @_backDeploy
+    // Tests recursive @backDeployed since `Array.print()` is also @backDeployed
     _values.print()
   }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public static var empty: Self { IntArray([]) }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public func toCountable() -> any Countable { self }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   @inlinable
   public subscript(_ i: Int) -> Int {
     get { _values[i] }
@@ -154,13 +154,13 @@ extension IntArray {
   }
   
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public var rawValues: [Int] {
     _read { yield _values }
   }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public mutating func removeLast() -> Int? {
     defer { _values.removeLast() }
     return _values.last
@@ -169,36 +169,36 @@ extension IntArray {
 
 extension ReferenceIntArray {
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public convenience init() { self.init([]) }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public final var values: [Int] { _values }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public final func print() {
-    // Tests recursive @_backDeploy since `Array.print()` is also @_backDeploy
+    // Tests recursive @backDeployed since `Array.print()` is also @backDeployed
     _values.print()
   }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public final func copy() -> ReferenceIntArray {
     return ReferenceIntArray(values)
   }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public final class var empty: ReferenceIntArray { ReferenceIntArray([]) }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public final func toCountable() -> any Countable { self }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   @inlinable
   public final subscript(_ i: Int) -> Int {
     get { _values[i] }
@@ -206,13 +206,13 @@ extension ReferenceIntArray {
   }
   
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public final var rawValues: [Int] {
     _read { yield _values }
   }
 
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public final func removeLast() -> Int? {
     defer { _values.removeLast() }
     return _values.last
@@ -221,7 +221,7 @@ extension ReferenceIntArray {
 
 extension Array {
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public func print() {
     testPrint(handle: #dsohandle, description)
   }
@@ -229,7 +229,7 @@ extension Array {
 
 extension BadError {
   @available(BackDeploy 1.0, *)
-  @_backDeploy(before: BackDeploy 2.0)
+  @backDeployed(before: BackDeploy 2.0)
   public init?(fromEmoji emoji: Character) {
     switch emoji {
     case "❗️": self = .bad
diff --git a/test/attr/attr_backDeployed.swift b/test/attr/attr_backDeployed.swift
index b06c5d89e8e..1704ba2ecd8 100644
--- a/test/attr/attr_backDeployed.swift
+++ b/test/attr/attr_backDeployed.swift
@@ -4,45 +4,45 @@
 // MARK: - Valid declarations
 
 // Ok, top level functions
-@_backDeploy(before: macOS 12.0)
+@backDeployed(before: macOS 12.0)
 public func backDeployedTopLevelFunc() {}
 
 // Ok, internal decls may be back deployed when @usableFromInline
-@_backDeploy(before: macOS 12.0)
+@backDeployed(before: macOS 12.0)
 @usableFromInline
 internal func backDeployedUsableFromInlineTopLevelFunc() {}
 
 // Ok, decls in a struct
 public struct TopLevelStruct {
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public init<T>(_ t: T) {}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func backDeployedMethod() {}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public var backDeployedComputedProperty: Int { 98 }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public subscript(_ index: Int) -> Int { index }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public var readWriteProperty: Int {
     get { 42 }
     set(newValue) {}
   }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public subscript(at index: Int) -> Int {
     get { 42 }
     set(newValue) {}
   }
 
   public var explicitReadAndModify: Int {
-    @_backDeploy(before: macOS 12.0)
+    @backDeployed(before: macOS 12.0)
     _read { yield 42 }
 
-    @_backDeploy(before: macOS 12.0)
+    @backDeployed(before: macOS 12.0)
     _modify {}
   }
 }
@@ -51,7 +51,7 @@ public struct TopLevelStruct {
 public enum TopLevelEnum {
   case a, b
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public init?(from name: String) {
     switch name {
     case "a": self = .a
@@ -60,10 +60,10 @@ public enum TopLevelEnum {
     }
   }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func backDeployedMethod() {}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public var name: String {
     switch self {
     case .a: return "a"
@@ -80,29 +80,29 @@ public class TopLevelClass {
     self.x = x
   }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public convenience init() {
     self.init(x: 1)
   }
 
   public func hook() {}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   final public func backDeployedFinalMethod() {}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   final public var backDeployedFinalComputedProperty: Int { 98 }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public static func backDeployedStaticMethod() {}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public final class func backDeployedClassMethod() {}
 }
 
 // Ok, final decls in a non-final, derived class
 public class DerivedTopLevelClass: TopLevelClass {
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   final public func backDeployedFinalMethodOnDerived() {}
 }
 
@@ -114,15 +114,15 @@ final public class FinalTopLevelClass {
     self.x = x
   }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public convenience init() {
     self.init(x: 1)
   }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func backDeployedMethod() {}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public var backDeployedComputedProperty: Int { 98 }
 }
 
@@ -135,15 +135,15 @@ public actor TopLevelActor {
     self.x = x
   }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public init() {
     self.init(x: 1)
   }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   final public func method() {}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   final public var computedProperty: Int { 98 }
 }
 
@@ -156,107 +156,107 @@ final public actor FinalTopLevelActor {
     self.x = x
   }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public init() {
     self.init(x: 1)
   }
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func method() {}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public var computedProperty: Int { 98 }
 }
 
 // Ok, decls in extensions of public types
 extension TopLevelStruct {
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func backDeployedExtensionMethod() {}
 }
 
 extension TopLevelClass {
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   final public func backDeployedExtensionMethod() {}
 }
 
 extension FinalTopLevelClass {
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func backDeployedExtensionMethod() {}
 }
 
 @available(SwiftStdlib 5.1, *)
 extension TopLevelActor {
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   final public func backDeployedExtensionMethod() {}
 }
 
 @available(SwiftStdlib 5.1, *)
 extension FinalTopLevelActor {
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func backDeployedExtensionMethod() {}
 }
 
 public protocol TopLevelProtocol {}
 
 extension TopLevelProtocol {
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func backDeployedExtensionMethod() {}
 }
 
 
 // MARK: - Unsupported declaration kinds
 
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to this declaration}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' attribute cannot be applied to this declaration}}
 public class CannotBackDeployClass {}
 
 public class CannotBackDeployClassDesignatedInit {
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' cannot be applied to a non-final initializer}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' cannot be applied to a non-final initializer}}
   public init(x: Int) {}
 }
 
 public final class CannotBackDeployClassDeinit {
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to deinitializer declarations}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' attribute cannot be applied to deinitializer declarations}}
   deinit {}
 }
 
 // Ok, final decls in a non-final, derived class
 public class CannotBackDeployOverride: TopLevelClass {
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' cannot be combined with 'override'}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' cannot be combined with 'override'}}
   final public override func hook() {}
 }
 
 @available(SwiftStdlib 5.1, *)
 public actor CannotBackDeployActorDesignatedInit {
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' cannot be applied to a non-final initializer}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' cannot be applied to a non-final initializer}}
   public init(x: Int) {}
 }
 
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to this declaration}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' attribute cannot be applied to this declaration}}
 public struct CannotBackDeployStruct {
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' must not be used on stored properties}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' must not be used on stored properties}}
   public var cannotBackDeployStoredProperty: Int = 83
 
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' must not be used on stored properties}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' must not be used on stored properties}}
   public lazy var cannotBackDeployLazyStoredProperty: Int = 15
 }
 
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to this declaration}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' attribute cannot be applied to this declaration}}
 public enum CannotBackDeployEnum {
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to this declaration}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' attribute cannot be applied to this declaration}}
   case cannotBackDeployEnumCase
 }
 
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' must not be used on stored properties}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' must not be used on stored properties}}
 public var cannotBackDeployTopLevelVar = 79
 
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to this declaration}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' attribute cannot be applied to this declaration}}
 extension TopLevelStruct {}
 
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to this declaration}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' attribute cannot be applied to this declaration}}
 protocol CannotBackDeployProtocol {}
 
 @available(SwiftStdlib 5.1, *)
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to this declaration}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' attribute cannot be applied to this declaration}}
 public actor CannotBackDeployActor {}
 
 
@@ -269,147 +269,152 @@ public struct FunctionBodyDiagnostics {
   fileprivate func fileprivateFunc() {} // expected-note {{instance method 'fileprivateFunc()' is not '@usableFromInline' or public}}
   private func privateFunc() {} // expected-note {{instance method 'privateFunc()' is not '@usableFromInline' or public}}
 
-  @_backDeploy(before: macOS 12.0)
+  @backDeployed(before: macOS 12.0)
   public func backDeployedMethod() {
-    struct Nested {} // expected-error {{type 'Nested' cannot be nested inside a '@_backDeploy' function}}
+    struct Nested {} // expected-error {{type 'Nested' cannot be nested inside a '@backDeployed' function}}
 
     publicFunc()
     usableFromInlineFunc()
-    internalFunc() // expected-error {{instance method 'internalFunc()' is internal and cannot be referenced from a '@_backDeploy' function}}
-    fileprivateFunc() // expected-error {{instance method 'fileprivateFunc()' is fileprivate and cannot be referenced from a '@_backDeploy' function}}
-    privateFunc() // expected-error {{instance method 'privateFunc()' is private and cannot be referenced from a '@_backDeploy' function}}
+    internalFunc() // expected-error {{instance method 'internalFunc()' is internal and cannot be referenced from a '@backDeployed' function}}
+    fileprivateFunc() // expected-error {{instance method 'fileprivateFunc()' is fileprivate and cannot be referenced from a '@backDeployed' function}}
+    privateFunc() // expected-error {{instance method 'privateFunc()' is private and cannot be referenced from a '@backDeployed' function}}
   }
 }
 
 
 // MARK: - Incompatible declarations
 
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' may not be used on fileprivate declarations}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' may not be used on fileprivate declarations}}
 fileprivate func filePrivateFunc() {}
 
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' may not be used on private declarations}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' may not be used on private declarations}}
 private func privateFunc() {}
 
-@_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' may not be used on internal declarations}}
+@backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' may not be used on internal declarations}}
 internal func internalFunc() {}
 
 private struct PrivateTopLevelStruct {
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' may not be used on private declarations}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' may not be used on private declarations}}
   public func effectivelyPrivateFunc() {}
 }
 
 public class TopLevelClass2 {
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' cannot be applied to a non-final instance method}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' cannot be applied to a non-final instance method}}
   public func nonFinalMethod() {}
 
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' cannot be applied to a non-final class method}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' cannot be applied to a non-final class method}}
   public class func nonFinalClassMethod() {}
 }
 
-@_backDeploy(before: macOS 12.0, macOS 13.0) // expected-error {{'@_backDeploy' contains multiple versions for macOS}}
+@backDeployed(before: macOS 12.0, macOS 13.0) // expected-error {{'@backDeployed' contains multiple versions for macOS}}
 public func duplicatePlatformsFunc1() {}
 
-@_backDeploy(before: macOS 12.0)
-@_backDeploy(before: macOS 13.0) // expected-error {{'@_backDeploy' contains multiple versions for macOS}}
+@backDeployed(before: macOS 12.0)
+@backDeployed(before: macOS 13.0) // expected-error {{'@backDeployed' contains multiple versions for macOS}}
 public func duplicatePlatformsFunc2() {}
 
-@_backDeploy(before: macOS 12.0)
+@backDeployed(before: macOS 12.0)
 @_alwaysEmitIntoClient // expected-error {{'@_alwaysEmitIntoClient' cannot be applied to a back deployed global function}}
 public func alwaysEmitIntoClientFunc() {}
 
-@_backDeploy(before: macOS 12.0)
+@backDeployed(before: macOS 12.0)
 @inlinable // Ok
 public func inlinableFunc() {}
 
-@_backDeploy(before: macOS 12.0)
+@backDeployed(before: macOS 12.0)
 @_transparent // expected-error {{'@_transparent' cannot be applied to a back deployed global function}}
 public func transparentFunc() {}
 
 
 // MARK: - Attribute parsing
 
-@_backDeploy(before: macos 12.0, iOS 15.0) // expected-warning {{unknown platform 'macos' for attribute '@_backDeploy'; did you mean 'macOS'?}} {{22-27=macOS}}
+@backDeployed(before: macos 12.0, iOS 15.0) // expected-warning {{unknown platform 'macos' for attribute '@backDeployed'; did you mean 'macOS'?}} {{23-28=macOS}}
 public func incorrectPlatformCaseFunc() {}
 
-@_backDeploy(before: mscos 12.0, iOS 15.0) // expected-warning {{unknown platform 'mscos' for attribute '@_backDeploy'; did you mean 'macOS'?}} {{22-27=macOS}}
+@backDeployed(before: mscos 12.0, iOS 15.0) // expected-warning {{unknown platform 'mscos' for attribute '@backDeployed'; did you mean 'macOS'?}} {{23-28=macOS}}
 public func incorrectPlatformSimilarFunc() {}
 
-@_backDeploy(before: macOS 12.0, unknownOS 1.0) // expected-warning {{unknown platform 'unknownOS' for attribute '@_backDeploy'}}
+@backDeployed(before: macOS 12.0, unknownOS 1.0) // expected-warning {{unknown platform 'unknownOS' for attribute '@backDeployed'}}
 public func unknownOSFunc() {}
 
-@_backDeploy(before: @) // expected-error {{expected platform in '@_backDeploy' attribute}}
+@backDeployed(before: @) // expected-error {{expected platform in '@backDeployed' attribute}}
 public func badPlatformFunc1() {}
 
-@_backDeploy(before: @ 12.0) // expected-error {{expected platform in '@_backDeploy' attribute}}
+@backDeployed(before: @ 12.0) // expected-error {{expected platform in '@backDeployed' attribute}}
 public func badPlatformFunc2() {}
 
-@_backDeploy(before: macOS) // expected-error {{expected version number in '@_backDeploy' attribute}}
+@backDeployed(before: macOS) // expected-error {{expected version number in '@backDeployed' attribute}}
 public func missingVersionFunc1() {}
 
-@_backDeploy(before: macOS 12.0, iOS) // expected-error {{expected version number in '@_backDeploy' attribute}}
+@backDeployed(before: macOS 12.0, iOS) // expected-error {{expected version number in '@backDeployed' attribute}}
 public func missingVersionFunc2() {}
 
-@_backDeploy(before: macOS, iOS) // expected-error 2{{expected version number in '@_backDeploy' attribute}}
+@backDeployed(before: macOS, iOS) // expected-error 2{{expected version number in '@backDeployed' attribute}}
 public func missingVersionFunc3() {}
 
-@_backDeploy(before: macOS 12.0, iOS 15.0,) // expected-error {{unexpected ',' separator}}
+@backDeployed(before: macOS 12.0, iOS 15.0,) // expected-error {{unexpected ',' separator}}
 public func unexpectedSeparatorFunc() {}
 
-@_backDeploy(before: macOS 12.0.1) // expected-warning {{'@_backDeploy' only uses major and minor version number}}
+@backDeployed(before: macOS 12.0.1) // expected-warning {{'@backDeployed' only uses major and minor version number}}
 public func patchVersionFunc() {}
 
-@_backDeploy(before: macOS 12.0, * 9.0) // expected-warning {{* as platform name has no effect in '@_backDeploy' attribute}}
+@backDeployed(before: macOS 12.0, * 9.0) // expected-warning {{* as platform name has no effect in '@backDeployed' attribute}}
 public func wildcardWithVersionFunc() {}
 
-@_backDeploy(before: macOS 12.0, *) // expected-warning {{* as platform name has no effect in '@_backDeploy' attribute}}
+@backDeployed(before: macOS 12.0, *) // expected-warning {{* as platform name has no effect in '@backDeployed' attribute}}
 public func trailingWildcardFunc() {}
 
-@_backDeploy(before: macOS 12.0, *, iOS 15.0) // expected-warning {{* as platform name has no effect in '@_backDeploy' attribute}}
+@backDeployed(before: macOS 12.0, *, iOS 15.0) // expected-warning {{* as platform name has no effect in '@backDeployed' attribute}}
 public func embeddedWildcardFunc() {}
 
-@_backDeploy(before: _myProject 3.0) // expected-error {{reference to undefined version '3.0' for availability macro '_myProject'}}
+@backDeployed(before: _myProject 3.0) // expected-error {{reference to undefined version '3.0' for availability macro '_myProject'}}
 public func macroVersioned() {}
 
-@_backDeploy(before: _myProject) // expected-error {{reference to undefined version '0' for availability macro '_myProject'}}
+@backDeployed(before: _myProject) // expected-error {{reference to undefined version '0' for availability macro '_myProject'}}
 public func missingMacroVersion() {}
 
 // Fall back to the default diagnostic when the macro is unknown.
-@_backDeploy(before: _unknownMacro) // expected-warning {{unknown platform '_unknownMacro' for attribute '@_backDeploy'}}
-// expected-error@-1 {{expected version number in '@_backDeploy' attribute}}
+@backDeployed(before: _unknownMacro) // expected-warning {{unknown platform '_unknownMacro' for attribute '@backDeployed'}}
+// expected-error@-1 {{expected version number in '@backDeployed' attribute}}
 public func unknownMacroMissingVersion() {}
 
-@_backDeploy(before: _unknownMacro 1.0) // expected-warning {{unknown platform '_unknownMacro' for attribute '@_backDeploy'}}
-// expected-error@-1 {{expected at least one platform version in '@_backDeploy' attribute}}
+@backDeployed(before: _unknownMacro 1.0) // expected-warning {{unknown platform '_unknownMacro' for attribute '@backDeployed'}}
+// expected-error@-1 {{expected at least one platform version in '@backDeployed' attribute}}
 public func unknownMacroVersioned() {}
 
-@_backDeploy(before: _unknownMacro 1.0, _myProject 2.0) // expected-warning {{unknown platform '_unknownMacro' for attribute '@_backDeploy'}}
+@backDeployed(before: _unknownMacro 1.0, _myProject 2.0) // expected-warning {{unknown platform '_unknownMacro' for attribute '@backDeployed'}}
 public func knownAndUnknownMacroVersioned() {}
 
-@_backDeploy() // expected-error {{expected 'before:' in '@_backDeploy' attribute}}
-// expected-error@-1 {{expected at least one platform version in '@_backDeploy' attribute}}
+@backDeployed() // expected-error {{expected 'before:' in '@backDeployed' attribute}}
+// expected-error@-1 {{expected at least one platform version in '@backDeployed' attribute}}
 public func emptyAttributeFunc() {}
 
-@_backDeploy(macOS 12.0) // expected-error {{expected 'before:' in '@_backDeploy' attribute}} {{14-14=before:}}
+@backDeployed(macOS 12.0) // expected-error {{expected 'before:' in '@backDeployed' attribute}} {{15-15=before:}}
 public func missingBeforeFunc() {}
 
-@_backDeploy(before) // expected-error {{expected ':' after 'before' in '@_backDeploy' attribute}} {{20-20=:}}
-// expected-error@-1 {{expected at least one platform version in '@_backDeploy' attribute}}
+@backDeployed(before) // expected-error {{expected ':' after 'before' in '@backDeployed' attribute}} {{21-21=:}}
+// expected-error@-1 {{expected at least one platform version in '@backDeployed' attribute}}
 public func missingColonAfterBeforeFunc() {}
 
-@_backDeploy(before macOS 12.0) // expected-error {{expected ':' after 'before' in '@_backDeploy' attribute}} {{20-20=:}}
+@backDeployed(before macOS 12.0) // expected-error {{expected ':' after 'before' in '@backDeployed' attribute}} {{21-21=:}}
 public func missingColonBetweenBeforeAndPlatformFunc() {}
 
-@_backDeploy(before: macOS 12.0,) // expected-error {{unexpected ',' separator}} {{32-33=}}
+@backDeployed(before: macOS 12.0,) // expected-error {{unexpected ',' separator}} {{33-34=}}
 public func unexpectedTrailingCommaFunc() {}
 
-@_backDeploy(before: macOS 12.0,, iOS 15.0) // expected-error {{unexpected ',' separator}} {{33-34=}}
+@backDeployed(before: macOS 12.0,, iOS 15.0) // expected-error {{unexpected ',' separator}} {{34-35=}}
 public func extraCommaFunc() {}
 
-@_backDeploy(before:) // expected-error {{expected at least one platform version in '@_backDeploy' attribute}}
+@backDeployed(before:) // expected-error {{expected at least one platform version in '@backDeployed' attribute}}
 public func emptyPlatformVersionsFunc() {}
 
-@_backDeploy // expected-error {{expected '(' in '@_backDeploy' attribute}}
+@backDeployed // expected-error {{expected '(' in '@backDeployed' attribute}}
 public func expectedLeftParenFunc() {}
 
-@_backDeploy(before: macOS 12.0 // expected-note {{to match this opening '('}}
-public func expectedRightParenFunc() {} // expected-error {{expected ')' in '@_backDeploy' argument list}}
+@backDeployed(before: macOS 12.0 // expected-note {{to match this opening '('}}
+public func expectedRightParenFunc() {} // expected-error {{expected ')' in '@backDeployed' argument list}}
+
+// MARK: - Legacy attribute spelling
+
+@_backDeploy(before: macOS 12.0)
+public func legacyBackDeployFunc() {}
diff --git a/test/attr/attr_backDeployed_availability.swift b/test/attr/attr_backDeployed_availability.swift
index ac68e02ea54..fcb10653344 100644
--- a/test/attr/attr_backDeployed_availability.swift
+++ b/test/attr/attr_backDeployed_availability.swift
@@ -2,84 +2,84 @@
 
 // REQUIRES: OS=macosx
 
-@_backDeploy(before: macOS 12) // Ok, introduced availability is inferred to be macOS 10.9
+@backDeployed(before: macOS 12) // Ok, introduced availability is inferred to be macOS 10.9
 public func topLevelFunc() {}
 
 public struct TopLevelStruct {
-  @_backDeploy(before: macOS 12) // Ok, introduced availability is inferred to be macOS 10.9
+  @backDeployed(before: macOS 12) // Ok, introduced availability is inferred to be macOS 10.9
   public func methodInStruct() {}
 }
 
 extension TopLevelStruct {
-  @_backDeploy(before: macOS 12) // Ok, introduced availability is inferred to be macOS 10.9
+  @backDeployed(before: macOS 12) // Ok, introduced availability is inferred to be macOS 10.9
   public func methodInExtension() {}
 }
 
 @available(macOS 11, *)
-@_backDeploy(before: macOS 12) // Ok, introduced availability is earlier than macOS 12
+@backDeployed(before: macOS 12) // Ok, introduced availability is earlier than macOS 12
 public func availableBeforeBackDeployment() {}
 
 @available(macOS 12, *) // expected-note {{'availableSameVersionAsBackDeployment()' was introduced in macOS 12}}
-@_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because 'availableSameVersionAsBackDeployment()' is not available before macOS 12}}
+@backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because 'availableSameVersionAsBackDeployment()' is not available before macOS 12}}
 public func availableSameVersionAsBackDeployment() {}
 
 @available(macOS 12.1, *) // expected-note {{'availableAfterBackDeployment()' was introduced in macOS 12.1}}
-@_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because 'availableAfterBackDeployment()' is not available before macOS 12}}
+@backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because 'availableAfterBackDeployment()' is not available before macOS 12}}
 public func availableAfterBackDeployment() {}
 
 @available(macOS 12, iOS 13, *)
-@_backDeploy(before: iOS 12) // This is invalid but it can only be diagnosed when building for iOS
+@backDeployed(before: iOS 12) // This is invalid but it can only be diagnosed when building for iOS
 public func availableAfterBackDeploymentForInactiveAttribute() {}
 
 @available(macOS 12, *) // expected-note {{'memberFunc()' was introduced in macOS 12}}
 public struct AvailableMacOS12Struct {
-  @_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because 'memberFunc()' is not available before macOS 12}}
+  @backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because 'memberFunc()' is not available before macOS 12}}
   public func memberFunc() {}
 }
 
 @available(macOS 12, *) // expected-note {{'methodInExtensionAvailableMacOS12()' was introduced in macOS 12}}
 extension TopLevelStruct {
-  @_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because 'methodInExtensionAvailableMacOS12()' is not available before macOS 12}}
+  @backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because 'methodInExtensionAvailableMacOS12()' is not available before macOS 12}}
   public func methodInExtensionAvailableMacOS12() {}
 }
 
 extension TopLevelStruct {
   @available(macOS 12, *) // expected-note {{getter for 'propertyAvailableMacOS12' was introduced in macOS 12}}
   public var propertyAvailableMacOS12: Int {
-    @_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because getter for 'propertyAvailableMacOS12' is not available before macOS 12}}
+    @backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because getter for 'propertyAvailableMacOS12' is not available before macOS 12}}
     get { 0 }
   }
 }
 
 @available(macOS, unavailable) // expected-note {{'unavailableMacOSFunc()' has been explicitly marked unavailable here}}
-@_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because 'unavailableMacOSFunc()' is unavailable on macOS}}
+@backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because 'unavailableMacOSFunc()' is unavailable on macOS}}
 public func unavailableMacOSFunc() {}
 
 @available(macOS, unavailable)
 @available(iOS, unavailable)
-@_backDeploy(before: iOS 12) // This is invalid but it can only be diagnosed when building for iOS
+@backDeployed(before: iOS 12) // This is invalid but it can only be diagnosed when building for iOS
 public func unavailableForInactiveAttributeFunc() {}
 
 @available(*, unavailable) // expected-note {{'alwaysUnavailableFunc()' has been explicitly marked unavailable here}}
-@_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because 'alwaysUnavailableFunc()' is unavailable on macOS}}
+@backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because 'alwaysUnavailableFunc()' is unavailable on macOS}}
 public func alwaysUnavailableFunc() {}
 
 @available(macOS, unavailable) // expected-note {{'memberFunc()' has been explicitly marked unavailable here}}
 public struct UnavailableMacOSStruct {
-  @_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because 'memberFunc()' is unavailable on macOS}}
+  @backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because 'memberFunc()' is unavailable on macOS}}
   public func memberFunc() {}
 }
 
 @available(macOS, unavailable) // expected-note {{'methodInUnavailableExtension()' has been explicitly marked unavailable here}}
 extension TopLevelStruct {
-  @_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because 'methodInUnavailableExtension()' is unavailable on macOS}}
+  @backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because 'methodInUnavailableExtension()' is unavailable on macOS}}
   public func methodInUnavailableExtension() {}
 }
 
 extension TopLevelStruct {
   @available(macOS, unavailable) // expected-note {{getter for 'unavailableMacOSProperty' has been explicitly marked unavailable here}}
   public var unavailableMacOSProperty: Int {
-    @_backDeploy(before: macOS 12) // expected-error {{'@_backDeploy' has no effect because getter for 'unavailableMacOSProperty' is unavailable on macOS}}
+    @backDeployed(before: macOS 12) // expected-error {{'@backDeployed' has no effect because getter for 'unavailableMacOSProperty' is unavailable on macOS}}
     get { 0 }
   }
 }
diff --git a/test/attr/attr_backDeployed_evolution.swift b/test/attr/attr_backDeployed_evolution.swift
index 6b98bf8d3d5..757c9d00f3a 100644
--- a/test/attr/attr_backDeployed_evolution.swift
+++ b/test/attr/attr_backDeployed_evolution.swift
@@ -1,6 +1,6 @@
 //
 // At a high level, this test is designed to verify that use of declarations
-// annotated with @_backDeploy behave as expected when running a client binary
+// annotated with @backDeployed behave as expected when running a client binary
 // on an older OS that does not have the back deployed APIs. The
 // BackDeployHelper framework has a number of APIs that are available in the
 // OSes identified by the "BackDeploy 1.0" availability macro and are back
diff --git a/test/attr/attr_inlinable_available.swift b/test/attr/attr_inlinable_available.swift
index 63e57545726..78d9b93660b 100644
--- a/test/attr/attr_inlinable_available.swift
+++ b/test/attr/attr_inlinable_available.swift
@@ -615,12 +615,12 @@ public func spiDeployedUseNoAvailable( // expected-note 3 {{add @available attri
 }
 
 
-// MARK: - @_backDeploy functions
+// MARK: - @backDeployed functions
 
-// @_backDeploy acts like @inlinable.
+// @backDeployed acts like @inlinable.
 
 @available(macOS 10.10, *)
-@_backDeploy(before: macOS 999.0)
+@backDeployed(before: macOS 999.0)
 public func backDeployedToInliningTarget(
   _: NoAvailable,
   _: BeforeInliningTarget,
diff --git a/test/attr/attr_objc.swift b/test/attr/attr_objc.swift
index 398ed1ff9bb..08801c8ed5b 100644
--- a/test/attr/attr_objc.swift
+++ b/test/attr/attr_objc.swift
@@ -2668,10 +2668,10 @@ class issue55246 {
   // access-note-adjust{{@objc}} expected-error@-1 {{subscript cannot be marked @objc because it has generic parameters}}
 }
 
-// @_backDeploy
+// @backDeployed
 
 public class BackDeployClass {
-  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' must not be used on an '@objc' instance method}}
+  @backDeployed(before: macOS 12.0) // expected-error {{'@backDeployed' must not be used on an '@objc' instance method}}
   @objc
   final public func objcMethod() {}
 }