diff --git a/stdlib/public/core/CTypes.swift b/stdlib/public/core/CTypes.swift
index a07d756b3f17c..a68bf7ddba69c 100644
--- a/stdlib/public/core/CTypes.swift
+++ b/stdlib/public/core/CTypes.swift
@@ -56,11 +56,11 @@ public typealias CLong = Int
 /// The C 'long long' type.
 public typealias CLongLong = Int64
 
+#if !(os(macOS) && arch(x86_64))
 /// The C '_Float16' type.
-@available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-@available(macOS, unavailable)
-@available(macCatalyst, unavailable)
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
 public typealias CFloat16 = Float16
+#endif
 
 /// The C 'float' type.
 public typealias CFloat = Float
diff --git a/stdlib/public/core/Codable.swift b/stdlib/public/core/Codable.swift
index 3c9d02bcd839f..5057970760b23 100644
--- a/stdlib/public/core/Codable.swift
+++ b/stdlib/public/core/Codable.swift
@@ -4730,9 +4730,8 @@ extension RawRepresentable where RawValue == Float, Self: Decodable {
   }
 }
 
-@available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-@available(macOS, unavailable)
-@available(macCatalyst, unavailable)
+#if !(os(macOS) && arch(x86_64))
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
 extension Float16: Codable {
   /// Creates a new instance by decoding from the given decoder.
   ///
@@ -4763,6 +4762,7 @@ extension Float16: Codable {
     try Float(self).encode(to: encoder)
   }
 }
+#endif
 
 extension Int: Codable {
   /// Creates a new instance by decoding from the given decoder.
diff --git a/stdlib/public/core/FloatingPointParsing.swift.gyb b/stdlib/public/core/FloatingPointParsing.swift.gyb
index 0ae7a0a3e6dbb..a3c4b1b883bfd 100644
--- a/stdlib/public/core/FloatingPointParsing.swift.gyb
+++ b/stdlib/public/core/FloatingPointParsing.swift.gyb
@@ -42,13 +42,12 @@ internal func _isspace_clocale(_ u: UTF16.CodeUnit) -> Bool {
 
 % if bits == 80:
 #if !(os(Windows) || os(Android)) && (arch(i386) || arch(x86_64))
+% elif bits == 16:
+#if !(os(macOS) && arch(x86_64))
 % end
 
-//===--- Parsing ----------------------------------------------------------===//
 %if bits == 16:
-@available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-@available(macOS, unavailable)
-@available(macCatalyst, unavailable)
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
 %end
 extension ${Self}: LosslessStringConvertible {
   /// Creates a new instance from the given string.
@@ -136,7 +135,7 @@ extension ${Self}: LosslessStringConvertible {
   %if bits == 16:
     self.init(Substring(text))
   %else:
-    if #available(macOS 10.16, iOS 14.0, watchOS 7.0, tvOS 14.0, *) {
+    if #available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *) {
       self.init(Substring(text))
     } else {
       self = 0.0
@@ -166,13 +165,7 @@ extension ${Self}: LosslessStringConvertible {
   // In particular, we still have to export
   // _swift_stdlib_strtoXYZ_clocale()
   // as ABI to support old compiled code that still requires it.
-%if bits == 16:
-  @available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-  @available(macOS, unavailable)
-  @available(macCatalyst, unavailable)
-%else:
-  @available(macOS 10.16, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-%end
+  @available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
   public init?(_ text: Substring) {
     self = 0.0
     let success = withUnsafeMutablePointer(to: &self) { p -> Bool in
@@ -196,7 +189,7 @@ extension ${Self}: LosslessStringConvertible {
   }
 }
 
-% if bits == 80:
+% if bits in [16,80]:
 #endif
 % end
 
diff --git a/stdlib/public/core/FloatingPointTypes.swift.gyb b/stdlib/public/core/FloatingPointTypes.swift.gyb
index 59a3a0379d2a8..ac7ec998e675d 100644
--- a/stdlib/public/core/FloatingPointTypes.swift.gyb
+++ b/stdlib/public/core/FloatingPointTypes.swift.gyb
@@ -40,7 +40,7 @@ RawSignificand = 'UInt' + str(SignificandSize)
 
 def Availability(bits):
     if bits == 16:
-        return '@available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)\n@available(macOS, unavailable)\n@available(macCatalyst, unavailable)'
+        return '@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)'
     return ''
 
 if Self == 'Float16':
@@ -65,6 +65,8 @@ else:
 
 % if bits == 80:
 #if !(os(Windows) || os(Android)) && (arch(i386) || arch(x86_64))
+% elif bits == 16:
+#if !(os(macOS) && arch(x86_64))
 % end
 
 ${SelfDocComment}
@@ -1106,8 +1108,10 @@ extension ${Self} {
 %   srcBits = src_type.bits
 %   That = src_type.stdlib_name
 
-%   if (srcBits == 80) and (bits != 80):
+%   if srcBits == 80:
 #if !(os(Windows) || os(Android)) && (arch(i386) || arch(x86_64))
+%   elif srcBits == 16:
+#if !(os(macOS) && arch(x86_64))
 %   end
 
 %   if srcBits == bits:
@@ -1192,7 +1196,7 @@ extension ${Self} {
     }
   }
 
-%   if (srcBits == 80) and (bits != 80):
+%   if srcBits in [16,80]:
 #endif
 %   end
 % end
@@ -1343,12 +1347,12 @@ internal struct _${Self}AnyHashableBox: _AnyHashableBox {
 // Deprecated operators
 //===----------------------------------------------------------------------===//
 
-% if bits == 80:
+% if bits in [16,80]:
 #else
 
 ${SelfDocComment}
 @frozen
-@available(*, unavailable, message: "Float80 is not available on target platform.")
+@available(*, unavailable, message: "${Self} is not available on target platform.")
 public struct ${Self} {
   /// Creates a value initialized to zero.
   @_transparent
diff --git a/stdlib/public/core/IntegerTypes.swift.gyb b/stdlib/public/core/IntegerTypes.swift.gyb
index c275c30d86d2e..4b4c6c7cbe716 100644
--- a/stdlib/public/core/IntegerTypes.swift.gyb
+++ b/stdlib/public/core/IntegerTypes.swift.gyb
@@ -1129,6 +1129,8 @@ public struct ${Self}
 
 %     if FloatType == 'Float80':
 #if !(os(Windows) || os(Android)) && (arch(i386) || arch(x86_64))
+%     elif FloatType == 'Float16':
+#if !(os(macOS) && arch(x86_64))
 %     end
 
   /// Creates an integer from the given floating-point value, rounding toward
@@ -1152,9 +1154,7 @@ public struct ${Self}
   ///   `source` must be representable in this type after rounding toward
   ///   zero.
 %     if FloatType == 'Float16':
-  @available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-  @available(macOS, unavailable)
-  @available(macCatalyst, unavailable)
+  @available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
 %     end
   @_transparent
   public init(_ source: ${FloatType}) {
@@ -1184,9 +1184,7 @@ public struct ${Self}
   ///
   /// - Parameter source: A floating-point value to convert to an integer.
 %     if FloatType == 'Float16':
-  @available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-  @available(macOS, unavailable)
-  @available(macCatalyst, unavailable)
+  @available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
 %     end
   @_transparent
   public init?(exactly source: ${FloatType}) {
@@ -1206,7 +1204,7 @@ public struct ${Self}
     self._value = Builtin.fpto${u}i_FPIEEE${FloatBits}_${BuiltinName}(source._value)
   }
 
-%     if FloatType == 'Float80':
+%     if FloatType in ['Float16', 'Float80']:
 #endif
 %     end
 
diff --git a/stdlib/public/core/Runtime.swift b/stdlib/public/core/Runtime.swift
index 086588cffc43d..c1e72cdd0eae2 100644
--- a/stdlib/public/core/Runtime.swift
+++ b/stdlib/public/core/Runtime.swift
@@ -293,6 +293,7 @@ internal struct _Buffer72 {
   }
 }
 
+#if !(os(macOS) && arch(x86_64))
 // Note that this takes a Float32 argument instead of Float16, because clang
 // doesn't have _Float16 on all platforms yet.
 @_silgen_name("swift_float16ToString")
@@ -303,9 +304,7 @@ internal func _float16ToStringImpl(
   _ debug: Bool
 ) -> Int
 
-@available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-@available(macOS, unavailable)
-@available(macCatalyst, unavailable)
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
 internal func _float16ToString(
   _ value: Float16,
   debug: Bool
@@ -317,6 +316,7 @@ internal func _float16ToString(
   }
   return (buffer, length)
 }
+#endif
 
 // Returns a UInt64, but that value is the length of the string, so it's
 // guaranteed to fit into an Int. This is part of the ABI, so we can't
diff --git a/stdlib/public/core/SIMDVectorTypes.swift.gyb b/stdlib/public/core/SIMDVectorTypes.swift.gyb
index 0faf4371bc7f7..0002f8cdcf293 100644
--- a/stdlib/public/core/SIMDVectorTypes.swift.gyb
+++ b/stdlib/public/core/SIMDVectorTypes.swift.gyb
@@ -253,11 +253,10 @@ extension ${Self}: SIMDScalar {
 %end
 
 %for (Self, bits) in [('Float16',16), ('Float',32), ('Double',64)]:
-%if bits == 16:
-@available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-@available(macOS, unavailable)
-@available(macCatalyst, unavailable)
-%end
+% if bits == 16:
+#if !(os(macOS) && arch(x86_64))
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+% end
 extension ${Self} : SIMDScalar {
 
   public typealias SIMDMaskScalar = Int${bits}
@@ -299,5 +298,8 @@ extension ${Self} : SIMDScalar {
 
 % end
 }
+% if bits == 16:
+#endif
+% end
 
 %end
diff --git a/test/ClangImporter/simd.swift b/test/ClangImporter/simd.swift
index e308b0792b46a..69eb614057023 100644
--- a/test/ClangImporter/simd.swift
+++ b/test/ClangImporter/simd.swift
@@ -22,12 +22,14 @@ let ll3_value: ll3 = makes_ll3()
 let ll8_value: ll8 = makes_ll8()
 let ull4_value: ull4 = makes_ull4()
 let ull16_value: ull16 = makes_ull16()
+#if !(os(macOS) && arch(x86_64))
 let half2_value: half2 = makes_half2()
 let half3_value: half3 = makes_half3()
 let half4_value: half4 = makes_half4()
 let half8_value: half8 = makes_half8()
 let half16_value: half16 = makes_half16()
 let half32_value: half32 = makes_half32()
+#endif
 let float2_value: float2 = makes_float2()
 let float3_value: float3 = makes_float3()
 let float4_value: float4 = makes_float4()
@@ -58,12 +60,14 @@ takes_ll3(ll3_value)
 takes_ll8(ll8_value)
 takes_ull4(ull4_value)
 takes_ull16(ull16_value)
+#if !(os(macOS) && arch(x86_64))
 takes_half2(half2_value)
 takes_half3(half3_value)
 takes_half4(half4_value)
 takes_half8(half8_value)
 takes_half16(half16_value)
 takes_half32(half32_value)
+#endif
 takes_float2(float2_value)
 takes_float3(float3_value)
 takes_float4(float4_value)
diff --git a/test/stdlib/PrintFloat.swift.gyb b/test/stdlib/PrintFloat.swift.gyb
index ec24b7ba11113..b151df19893df 100644
--- a/test/stdlib/PrintFloat.swift.gyb
+++ b/test/stdlib/PrintFloat.swift.gyb
@@ -345,11 +345,9 @@ let PrintTests = TestSuite("FloatingPointPrinting")
 
 % for FloatType in ['Float16', 'Float', 'Double', 'Float80']:
 % if FloatType == 'Float16':
-@available(iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-@available(macOS, unavailable)
-@available(macCatalyst, unavailable)
-% end
-% if FloatType == 'Float80':
+#if !(os(macOS) && arch(x86_64))
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+% elif FloatType == 'Float80':
 #if !os(Windows) && (arch(i386) || arch(x86_64))
 % end
 
@@ -425,7 +423,7 @@ fileprivate func expectAccurateDescription(_ object: ${FloatType},
   // that the result is not closer.  Note this requires higher-precision
   // arithmetic.
 }
-% if FloatType == 'Float80':
+% if FloatType in ['Float16','Float80']:
 #endif
 % end
 % end
@@ -587,8 +585,8 @@ PrintTests.test("Printable_CDouble") {
   expectDescription("-1.0", CDouble(-1.0))
 }
 
-#if !os(macOS) && !(os(iOS) && targetEnvironment(macCatalyst))
-if #available(iOS 14.0, watchOS 7.0, tvOS 14.0, *) {
+#if !(os(macOS) && arch(x86_64))
+if #available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *) {
 PrintTests.test("Printable_Float16") {
   func asFloat16(_ f: Float16) -> Float16 { return f }