diff --git a/include/swift/Basic/Features.def b/include/swift/Basic/Features.def
index 66d57b27aaedc..0da7bf21c9cfe 100644
--- a/include/swift/Basic/Features.def
+++ b/include/swift/Basic/Features.def
@@ -561,6 +561,9 @@ EXPERIMENTAL_FEATURE(CheckImplementationOnly, true)
 /// report references to implementation-only imported modules.
 EXPERIMENTAL_FEATURE(CheckImplementationOnlyStrict, false)
 
+/// Check that use sites have the required @_spi import for operators.
+EXPERIMENTAL_FEATURE(EnforceSPIOperatorGroup, true)
+
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE
 #undef UPCOMING_FEATURE
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 7b6774729a8e0..611edf3a5d769 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -5536,9 +5536,19 @@ static bool checkAccess(const DeclContext *useDC, const ValueDecl *VD,
     return srcPkg && usePkg && usePkg->isSamePackageAs(srcPkg);
   }
   case AccessLevel::Public:
-  case AccessLevel::Open:
+  case AccessLevel::Open: {
+    if (VD->getASTContext().LangOpts.hasFeature(
+            Feature::EnforceSPIOperatorGroup) &&
+        VD->isOperator() && VD->isSPI()) {
+      const DeclContext *useFile = useDC->getModuleScopeContext();
+      if (useFile->getParentModule() == sourceDC->getParentModule())
+        return true;
+      auto *useSF = dyn_cast<SourceFile>(useFile);
+      return !useSF || useSF->isImportedAsSPI(VD);
+    }
     return true;
   }
+  }
   llvm_unreachable("bad access level");
 }
 
diff --git a/lib/AST/FeatureSet.cpp b/lib/AST/FeatureSet.cpp
index f18edb364e3ae..cdc5f2d3472e7 100644
--- a/lib/AST/FeatureSet.cpp
+++ b/lib/AST/FeatureSet.cpp
@@ -146,6 +146,7 @@ UNINTERESTING_FEATURE(SameElementRequirements)
 UNINTERESTING_FEATURE(SendingArgsAndResults)
 UNINTERESTING_FEATURE(CheckImplementationOnly)
 UNINTERESTING_FEATURE(CheckImplementationOnlyStrict)
+UNINTERESTING_FEATURE(EnforceSPIOperatorGroup)
 
 static bool findUnderscoredLifetimeAttr(Decl *decl) {
   auto hasUnderscoredLifetimeAttr = [](Decl *decl) {
diff --git a/test/SPI/Inputs/spi_helper.swift b/test/SPI/Inputs/spi_helper.swift
index 506ddd83ccb37..2eef695f7efe7 100644
--- a/test/SPI/Inputs/spi_helper.swift
+++ b/test/SPI/Inputs/spi_helper.swift
@@ -4,6 +4,10 @@ public protocol PublicProto {
   associatedtype Assoc
 }
 
+public struct PublicType {
+    public init() { }
+}
+
 public func publicFunc() { print("publicFunc") }
 
 func internalFunc() {}
@@ -94,3 +98,6 @@ public enum PublicEnum {
   case publicCase
   @_spi(HelperSPI) case spiCase
 }
+
+@_spi(HelperSPI) public func -(_ s1: PublicType, _ s2: PublicType) -> PublicType { s1 }
+@_spi(HelperSPI) public func +(_ s1: PublicType, _ s2: PublicType) -> PublicType { s1 }
diff --git a/test/SPI/local_spi_decls.swift b/test/SPI/local_spi_decls.swift
index d9350b4b3aa46..5f36727691912 100644
--- a/test/SPI/local_spi_decls.swift
+++ b/test/SPI/local_spi_decls.swift
@@ -115,11 +115,20 @@ public func publicFuncWithDefaultValue(_ p: SPIClass = SPIClass()) {} // expecte
 @_spi(S)
 public func spiFuncWithDefaultValue(_ p: SPIClass = SPIClass()) {}
 
+public struct PublicType {
+    public init() { }
+}
+@_spi(S) public func -(_ s1: PublicType, _ s2: PublicType) -> PublicType { s1 }
+
+public let o1 = PublicType()
+public let o2 = PublicType()
+
 @inlinable
 public func inlinablePublic() {
   spiFunc() // expected-error {{global function 'spiFunc()' cannot be used in an '@inlinable' function because it is SPI}}
   let _ = SPIClass() // expected-error {{class 'SPIClass' cannot be used in an '@inlinable' function because it is SPI}}
   // expected-error@-1 {{initializer 'init()' cannot be used in an '@inlinable' function because it is SPI}}
+  let _ = o1 - o2 // expected-error {{operator function '-' cannot be used in an '@inlinable' function because it is SPI}}
 }
 
 @_spi(S)
@@ -127,8 +136,11 @@ public func inlinablePublic() {
 public func inlinableSPI() {
   spiFunc()
   let _ = SPIClass()
+  let _ = o1 - o2
 }
 
 @_spi(S) func internalFunc() {} // expected-error {{internal global function cannot be declared '@_spi' because only public and open declarations can be '@_spi'}}
 
 @_spi(S) package func packageFunc() {} // expected-error {{package global function cannot be declared '@_spi' because only public and open declarations can be '@_spi'}}
+
+let _ = o1 - o2
diff --git a/test/SPI/private_swiftinterface.swift b/test/SPI/private_swiftinterface.swift
index 83d1b83e269cc..89c00474ba856 100644
--- a/test/SPI/private_swiftinterface.swift
+++ b/test/SPI/private_swiftinterface.swift
@@ -29,16 +29,16 @@
 
 /// Test the textual interfaces generated from this test.
 // RUN: %target-swift-frontend -typecheck %s -emit-module-interface-path %t/Main.swiftinterface -emit-private-module-interface-path %t/Main.private.swiftinterface -enable-library-evolution -swift-version 5 -I %t -module-name Main
-// RUN: %FileCheck -check-prefix=CHECK-PUBLIC %s < %t/Main.swiftinterface
-// RUN: %FileCheck -check-prefix=CHECK-PRIVATE %s < %t/Main.private.swiftinterface
+// RUN: cat %t/Main.swiftinterface | %FileCheck -check-prefix=CHECK-PUBLIC %s
+// RUN: cat %t/Main.private.swiftinterface | %FileCheck -check-prefix=CHECK-PRIVATE %s
 // RUN: %target-swift-frontend -typecheck-module-from-interface -I %t %t/Main.swiftinterface
 // RUN: %target-swift-frontend -typecheck-module-from-interface -I %t %t/Main.private.swiftinterface -module-name Main
 
 /// Both the public and private textual interfaces should have
 /// SPI information with `-library-level spi`.
 // RUN: %target-swift-frontend -typecheck %s -emit-module-interface-path %t/SPIModule.swiftinterface -emit-private-module-interface-path %t/SPIModule.private.swiftinterface -enable-library-evolution -swift-version 5 -I %t -module-name SPIModule -library-level spi
-// RUN: %FileCheck -check-prefix=CHECK-PRIVATE %s < %t/SPIModule.swiftinterface
-// RUN: %FileCheck -check-prefix=CHECK-PRIVATE %s < %t/SPIModule.private.swiftinterface
+// RUN: cat %t/SPIModule.swiftinterface | %FileCheck -check-prefix=CHECK-PRIVATE %s
+// RUN: cat %t/SPIModule.private.swiftinterface | %FileCheck -check-prefix=CHECK-PRIVATE %s
 // RUN: %target-swift-frontend -typecheck-module-from-interface -I %t %t/SPIModule.swiftinterface
 // RUN: %target-swift-frontend -typecheck-module-from-interface -I %t %t/SPIModule.private.swiftinterface -module-name SPIModule
 
@@ -238,6 +238,11 @@ extension IOIPublicStruct : LocalPublicProto {}
   // CHECK-PRIVATE: @_spi(S) private var spiTypeInFrozen1
 }
 
+public struct OpType {}
+@_spi(S) public func +(_ s1: OpType, _ s2: OpType) -> OpType { s1 }
+// CHECK-PRIVATE: @_spi(S) public func + (s1: {{.*}}.OpType, s2: {{.*}}.OpType) -> {{.*}}.OpType
+// CHECK-PUBLIC-NOT: func +
+
 // The dummy conformance should be only in the private swiftinterface for
 // SPI extensions.
 @_spi(LocalSPI)
diff --git a/test/SPI/public_client.swift b/test/SPI/public_client.swift
index 7c59617e4c02e..c9e994ab06e83 100644
--- a/test/SPI/public_client.swift
+++ b/test/SPI/public_client.swift
@@ -6,17 +6,21 @@
 // RUN: %target-swift-frontend -emit-module %S/Inputs/spi_helper.swift -module-name SPIHelper -emit-module-path %t/SPIHelper.swiftmodule -emit-module-interface-path %t/SPIHelper.swiftinterface -emit-private-module-interface-path %t/SPIHelper.private.swiftinterface -enable-library-evolution -swift-version 5 -parse-as-library
 
 /// Reading from swiftmodule
-// RUN: %target-typecheck-verify-swift -verify-ignore-unrelated -I %t -verify-ignore-unknown
+// RUN: %target-typecheck-verify-swift -verify-ignore-unrelated -I %t -verify-ignore-unknown \
+// RUN:   -enable-experimental-feature EnforceSPIOperatorGroup
 
 /// Reading from .private.swiftinterface
 // RUN: rm %t/SPIHelper.swiftmodule
-// RUN: %target-typecheck-verify-swift -verify-ignore-unrelated -I %t -verify-ignore-unknown
+// RUN: %target-typecheck-verify-swift -verify-ignore-unrelated -I %t -verify-ignore-unknown \
+// RUN:   -enable-experimental-feature EnforceSPIOperatorGroup
 
 /// Reading from the public .swiftinterface should raise errors on missing
 /// declarations.
 // RUN: rm %t/SPIHelper.private.swiftinterface
 // RUN: not %target-swift-frontend -typecheck -I %t %s
 
+// REQUIRES: swift_feature_EnforceSPIOperatorGroup
+
 import SPIHelper
 
 // Use the public API
@@ -40,8 +44,14 @@ otherApiFunc() // expected-error {{cannot find 'otherApiFunc' in scope}}
 public func publicUseOfSPI(param: SPIClass) -> SPIClass {} // expected-error 2{{cannot find type 'SPIClass' in scope}}
 public func publicUseOfSPI2() -> [SPIClass] {} // expected-error {{cannot find type 'SPIClass' in scope}}
 
+public let o1 = PublicType()
+public let o2 = PublicType()
+
 @inlinable
-func inlinable() -> SPIClass { // expected-error {{cannot find type 'SPIClass' in scope}}
+public func inlinable() -> SPIClass { // expected-error {{cannot find type 'SPIClass' in scope}}
   spiFunc() // expected-error {{cannot find 'spiFunc' in scope}}
   _ = SPIClass() // expected-error {{cannot find 'SPIClass' in scope}}
+  let _ = o1 - o2 // expected-error {{binary operator '-' cannot be applied to two 'PublicType' operands}}
 }
+
+let _ = o1 - o2 // expected-error {{binary operator '-' cannot be applied to two 'PublicType' operands}}
diff --git a/test/SPI/spi_client.swift b/test/SPI/spi_client.swift
index 574ff2569251f..9046af2384d36 100644
--- a/test/SPI/spi_client.swift
+++ b/test/SPI/spi_client.swift
@@ -61,10 +61,16 @@ public func inlinable1() -> SPIClass { // expected-error {{class 'SPIClass' cann
   _ = [SPIClass]() // expected-error {{class 'SPIClass' cannot be used in an '@inlinable' function because it is an SPI imported from 'SPIHelper'}}
 }
 
+public let o1 = PublicType()
+public let o2 = PublicType()
+
 @_spi(S)
 @inlinable
 public func inlinable2() -> SPIClass {
   spiFunc()
   _ = SPIClass()
   _ = [SPIClass]()
+  let _ = o1 - o2
 }
+
+let _ = o1 - o2