diff --git a/include/swift/AST/DiagnosticGroups.def b/include/swift/AST/DiagnosticGroups.def
index fa200714c7b05..9aa58a9d923b8 100644
--- a/include/swift/AST/DiagnosticGroups.def
+++ b/include/swift/AST/DiagnosticGroups.def
@@ -22,12 +22,12 @@
 
 GROUP(no_group, "")
 
-GROUP(DeprecatedDeclaration, "DeprecatedDeclaration.md")
-GROUP(Unsafe, "Unsafe.md")
-GROUP(UnknownWarningGroup, "UnknownWarningGroup.md")
-GROUP(PreconcurrencyImport, "PreconcurrencyImport.md")
-GROUP(StrictLanguageFeatures, "StrictLanguageFeatures.md")
-GROUP(ExistentialAny, "ExistentialAny.md")
+GROUP(DeprecatedDeclaration, "deprecated-declaration.md")
+GROUP(StrictMemorySafety, "strict-memory-safety.md")
+GROUP(UnknownWarningGroup, "unknown-warning-group.md")
+GROUP(PreconcurrencyImport, "preconcurrency-import.md")
+GROUP(StrictLanguageFeatures, "strict-language-features.md")
+GROUP(ExistentialAny, "existential-any.md")
 
 #define UNDEFINE_DIAGNOSTIC_GROUPS_MACROS
 #include "swift/AST/DefineDiagnosticGroupsMacros.h"
diff --git a/include/swift/AST/DiagnosticsFrontend.def b/include/swift/AST/DiagnosticsFrontend.def
index dc5d82d37657a..5bb3bc47b4213 100644
--- a/include/swift/AST/DiagnosticsFrontend.def
+++ b/include/swift/AST/DiagnosticsFrontend.def
@@ -590,7 +590,7 @@ ERROR(experimental_not_supported_in_production,none,
       "experimental feature '%0' cannot be enabled in production compiler",
       (StringRef))
 
-GROUPED_WARNING(command_line_conflicts_with_strict_safety,Unsafe,none,
+GROUPED_WARNING(command_line_conflicts_with_strict_safety,StrictMemorySafety,none,
       "'%0' is not memory-safe and should not be combined with "
       "strict memory safety checking", (StringRef))
 
diff --git a/include/swift/AST/DiagnosticsSema.def b/include/swift/AST/DiagnosticsSema.def
index 32a8d68d277e2..61a8097156b28 100644
--- a/include/swift/AST/DiagnosticsSema.def
+++ b/include/swift/AST/DiagnosticsSema.def
@@ -8196,7 +8196,7 @@ NOTE(note_use_of_unsafe_conformance_is_unsafe,none,
 NOTE(note_unsafe_storage,none,
      "%kindbase1 involves unsafe type %2", (bool, const ValueDecl *, Type))
 
-GROUPED_WARNING(decl_unsafe_storage,Unsafe,none,
+GROUPED_WARNING(decl_unsafe_storage,StrictMemorySafety,none,
       "%kindbase0 has storage involving unsafe types",
       (const Decl *))
 NOTE(decl_storage_mark_unsafe,none,
@@ -8206,11 +8206,11 @@ NOTE(decl_storage_mark_safe,none,
       "add '@safe' if this type encapsulates the unsafe storage in "
       "a safe interface", ())
 
-GROUPED_WARNING(unsafe_superclass,Unsafe,none,
+GROUPED_WARNING(unsafe_superclass,StrictMemorySafety,none,
      "%kindbase0 has superclass involving unsafe type %1", 
      (const ValueDecl *, Type))
 
-GROUPED_WARNING(conformance_involves_unsafe,Unsafe,none,
+GROUPED_WARNING(conformance_involves_unsafe,StrictMemorySafety,none,
      "conformance of %0 to %kind1 involves unsafe code; use '@unsafe' to "
      "indicate that the conformance is not memory-safe",
      (Type, const ValueDecl *))
@@ -8221,15 +8221,15 @@ NOTE(note_type_witness_unsafe,none,
       "unsafe type %0 cannot satisfy safe associated type %1",
       (Type, DeclName))
 
-GROUPED_WARNING(override_safe_with_unsafe,Unsafe,none,
+GROUPED_WARNING(override_safe_with_unsafe,StrictMemorySafety,none,
       "override of safe %0 with unsafe %0", (DescriptiveDeclKind))
 
-GROUPED_WARNING(preconcurrency_import_unsafe,Unsafe,none,
+GROUPED_WARNING(preconcurrency_import_unsafe,StrictMemorySafety,none,
       "@preconcurrency import is not memory-safe because it can silently "
       "introduce data races", ())
-GROUPED_WARNING(unsafe_without_unsafe,Unsafe,none,
+GROUPED_WARNING(unsafe_without_unsafe,StrictMemorySafety,none,
       "expression uses unsafe constructs but is not marked with 'unsafe'", ())
-GROUPED_WARNING(for_unsafe_without_unsafe,Unsafe,none,
+GROUPED_WARNING(for_unsafe_without_unsafe,StrictMemorySafety,none,
       "for-in loop uses unsafe constructs but is not marked with 'unsafe'", ())
 WARNING(no_unsafe_in_unsafe,none,
         "no unsafe operations occur within 'unsafe' expression", ())
diff --git a/test/Unsafe/safe.swift b/test/Unsafe/safe.swift
index f1d0633399cfd..a41c740d99706 100644
--- a/test/Unsafe/safe.swift
+++ b/test/Unsafe/safe.swift
@@ -91,9 +91,9 @@ func testUnsafeAsSequenceForEach() {
 
   // expected-warning@+1{{expression uses unsafe constructs but is not marked with 'unsafe'}}{{12-12=unsafe }}
   for _ in uas { } // expected-note{{conformance}}
-  // expected-warning@-1{{for-in loop uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}{{7-7=unsafe }}
+  // expected-warning@-1{{for-in loop uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}{{7-7=unsafe }}
 
-  for _ in unsafe uas { } // expected-warning{{for-in loop uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}{{7-7=unsafe }}
+  for _ in unsafe uas { } // expected-warning{{for-in loop uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}{{7-7=unsafe }}
 
   for unsafe _ in unsafe uas { } // okay
 }
diff --git a/test/Unsafe/safe_argument_suppression.swift b/test/Unsafe/safe_argument_suppression.swift
index 1a571607a95ef..4c60ad462265d 100644
--- a/test/Unsafe/safe_argument_suppression.swift
+++ b/test/Unsafe/safe_argument_suppression.swift
@@ -36,7 +36,7 @@ class NotSafeSubclass: NotSafe {
   _ = NotSafe[ns]
   NotSafe.doStatically(NotSafe.self)
 
-  ns.stillUnsafe() // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}
+  ns.stillUnsafe() // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}
   // expected-note@-1{{reference to parameter 'ns' involves unsafe type 'NotSafe'}}
   // expected-note@-2{{reference to unsafe instance method 'stillUnsafe()'}}
 }
diff --git a/test/Unsafe/unsafe-suppression.swift b/test/Unsafe/unsafe-suppression.swift
index eb3c108cb7c1d..a15344dbdd249 100644
--- a/test/Unsafe/unsafe-suppression.swift
+++ b/test/Unsafe/unsafe-suppression.swift
@@ -21,7 +21,7 @@ class C {
 
 class D1: C { // expected-note{{make class 'D1' @unsafe to allow unsafe overrides of safe superclass methods}}{{1-1=@unsafe }}
   @unsafe
-  override func method() { } // expected-warning{{override of safe instance method with unsafe instance method [Unsafe]}}
+  override func method() { } // expected-warning{{override of safe instance method with unsafe instance method [StrictMemorySafety]}}
 }
 
 @unsafe class D2: C {
@@ -34,7 +34,7 @@ protocol P {
 }
 
 struct S1: P {
-  // expected-warning@-1{{conformance of 'S1' to protocol 'P' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [Unsafe]}}{{12-12=@unsafe }}
+  // expected-warning@-1{{conformance of 'S1' to protocol 'P' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [StrictMemorySafety]}}{{12-12=@unsafe }}
   @unsafe
   func protoMethod() { } // expected-note{{unsafe instance method 'protoMethod()' cannot satisfy safe requirement}}
 }
@@ -48,7 +48,7 @@ struct S2: P {
 struct S3 { }
 
 extension S3: P {
-  // expected-warning@-1{{conformance of 'S3' to protocol 'P' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [Unsafe]}}{{15-15=@unsafe }}
+  // expected-warning@-1{{conformance of 'S3' to protocol 'P' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [StrictMemorySafety]}}{{15-15=@unsafe }}
   @unsafe
   func protoMethod() { } // expected-note{{unsafe instance method 'protoMethod()' cannot satisfy safe requirement}}
 }
@@ -116,12 +116,12 @@ extension UnsafeOuter {
 var yieldUnsafe: Int {
   _read {
     @unsafe let x = 5
-    yield x // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}
+    yield x // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}
     // expected-note@-1{{reference to unsafe let 'x'}}
   }
   _modify {
     @unsafe var x = 5
-    yield &x // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}
+    yield &x // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}
     // expected-note@-1{{reference to unsafe var 'x'}}
   }
 }
@@ -142,9 +142,9 @@ struct UnsafeSequence: @unsafe IteratorProtocol, @unsafe Sequence {
 }
 
 func forEachLoop(us: UnsafeSequence) {
-  for _ in us { } // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}{{12-12=unsafe }}
+  for _ in us { } // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}{{12-12=unsafe }}
   // expected-note@-1{{@unsafe conformance of 'UnsafeSequence' to protocol 'Sequence' involves unsafe code}}
-  // expected-warning@-2{{for-in loop uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}
+  // expected-warning@-2{{for-in loop uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}
   for _ in unsafe us { }
-  // expected-warning@-1{{for-in loop uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}
+  // expected-warning@-1{{for-in loop uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}
 }
diff --git a/test/Unsafe/unsafe.swift b/test/Unsafe/unsafe.swift
index 18c644da82366..0b4bbb809de04 100644
--- a/test/Unsafe/unsafe.swift
+++ b/test/Unsafe/unsafe.swift
@@ -16,7 +16,7 @@ protocol P {
   @unsafe func g()
 }
 
-struct XP: P { // expected-warning{{conformance of 'XP' to protocol 'P' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [Unsafe]}}{{12-12=@unsafe }}
+struct XP: P { // expected-warning{{conformance of 'XP' to protocol 'P' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [StrictMemorySafety]}}{{12-12=@unsafe }}
   @unsafe func f() { } // expected-note{{unsafe instance method 'f()' cannot satisfy safe requirement}}
   @unsafe func g() { }
 }
@@ -30,7 +30,7 @@ protocol Ptrable2 {
 }
 
 extension HasAPointerType: Ptrable2 { } // expected-note{{unsafe type 'HasAPointerType.Ptr' (aka 'PointerType') cannot satisfy safe associated type 'Ptr'}}
-  // expected-warning@-1{{conformance of 'HasAPointerType' to protocol 'Ptrable2' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [Unsafe]}}{{28-28=@unsafe }}
+  // expected-warning@-1{{conformance of 'HasAPointerType' to protocol 'Ptrable2' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [StrictMemorySafety]}}{{28-28=@unsafe }}
 
 struct UnsafeXP: @unsafe P {
   @unsafe func f() { }
@@ -44,7 +44,7 @@ protocol MultiP {
 
 struct ConformsToMultiP { }
 
-// expected-warning@+1{{conformance of 'ConformsToMultiP' to protocol 'MultiP' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [Unsafe]}}{{29-29=@unsafe }}
+// expected-warning@+1{{conformance of 'ConformsToMultiP' to protocol 'MultiP' involves unsafe code; use '@unsafe' to indicate that the conformance is not memory-safe [StrictMemorySafety]}}{{29-29=@unsafe }}
 extension ConformsToMultiP: MultiP {
   // expected-note@-1{{unsafe type 'UnsafeSuper' cannot satisfy safe associated type 'Ptr'}}
   @unsafe func f() -> UnsafeSuper {
@@ -74,7 +74,7 @@ class Super {
 }
 
 class Sub: Super { // expected-note{{make class 'Sub' @unsafe to allow unsafe overrides of safe superclass methods}}{{1-1=@unsafe }}
-  @unsafe override func f() { } // expected-warning{{override of safe instance method with unsafe instance method [Unsafe]}}
+  @unsafe override func f() { } // expected-warning{{override of safe instance method with unsafe instance method [StrictMemorySafety]}}
   @unsafe override func g() { }  
 }
 
@@ -117,7 +117,7 @@ class ExclusivityChecking {
   func f() { }
 };
 
-// expected-warning@+1{{class 'UnsafeSub' has superclass involving unsafe type 'UnsafeSuper' [Unsafe]}}{{1-1=@unsafe }}
+// expected-warning@+1{{class 'UnsafeSub' has superclass involving unsafe type 'UnsafeSuper' [StrictMemorySafety]}}{{1-1=@unsafe }}
 class UnsafeSub: UnsafeSuper { }
 
 // -----------------------------------------------------------------------
@@ -129,13 +129,13 @@ struct BufferThingy<T> {
 }
 
 func testConstruction() {
-  let _ = BufferThingy<Int>(count: 17) // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}{{11-11=unsafe }}
+  let _ = BufferThingy<Int>(count: 17) // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}{{11-11=unsafe }}
   // expected-note@-1{{reference to unsafe initializer 'init(count:)'}}
 }
 
 func testRHS(b: Bool, x: Int) {
   @unsafe let limit = 17
-  if b && x > limit { // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [Unsafe]}}{{6-6=unsafe }}
+  if b && x > limit { // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}{{6-6=unsafe }}
     // expected-note@-1{{reference to unsafe let 'limit'}}
   }
 }
@@ -171,7 +171,7 @@ typealias SuperUnsafe = UnsafeSuper
 
 @unsafe typealias SuperUnsafe2 = UnsafeSuper
 
-// expected-warning@+3{{enum 'HasUnsafeThings' has storage involving unsafe types [Unsafe]}}
+// expected-warning@+3{{enum 'HasUnsafeThings' has storage involving unsafe types [StrictMemorySafety]}}
 // expected-note@+2{{add '@unsafe' if this type is also unsafe to use}}{{1-1=@unsafe }}
 // expected-note@+1{{add '@safe' if this type encapsulates the unsafe storage in a safe interface}}{{1-1=@safe }}
 enum HasUnsafeThings {
@@ -181,7 +181,7 @@ case one(UnsafeSuper) // expected-note{{enum case 'one' involves unsafe type 'Un
 case two(UnsafeSuper) // expected-note{{enum case 'two' involves unsafe type 'UnsafeSuper'}}
 }
 
-// expected-warning@+3{{class 'ClassWithUnsafeStorage' has storage involving unsafe types [Unsafe]}}
+// expected-warning@+3{{class 'ClassWithUnsafeStorage' has storage involving unsafe types [StrictMemorySafety]}}
 // expected-note@+2{{add '@unsafe' if this type is also unsafe to use}}{{1-1=@unsafe }}
 // expected-note@+1{{add '@safe' if this type encapsulates the unsafe storage in a safe interface}}{{1-1=@safe }}
 class ClassWithUnsafeStorage {
diff --git a/userdocs/diagnostic_groups/DeprecatedDeclaration.md b/userdocs/diagnostic_groups/deprecated-declaration.md
similarity index 100%
rename from userdocs/diagnostic_groups/DeprecatedDeclaration.md
rename to userdocs/diagnostic_groups/deprecated-declaration.md
diff --git a/userdocs/diagnostic_groups/ExistentialAny.md b/userdocs/diagnostic_groups/existential-any.md
similarity index 100%
rename from userdocs/diagnostic_groups/ExistentialAny.md
rename to userdocs/diagnostic_groups/existential-any.md
diff --git a/userdocs/diagnostic_groups/PreconcurrencyImport.md b/userdocs/diagnostic_groups/preconcurrency-import.md
similarity index 100%
rename from userdocs/diagnostic_groups/PreconcurrencyImport.md
rename to userdocs/diagnostic_groups/preconcurrency-import.md
diff --git a/userdocs/diagnostic_groups/StrictLanguageFeatures.md b/userdocs/diagnostic_groups/strict-language-features.md
similarity index 100%
rename from userdocs/diagnostic_groups/StrictLanguageFeatures.md
rename to userdocs/diagnostic_groups/strict-language-features.md
diff --git a/userdocs/diagnostic_groups/UnknownWarningGroup.md b/userdocs/diagnostic_groups/unknown-warning-group.md
similarity index 100%
rename from userdocs/diagnostic_groups/UnknownWarningGroup.md
rename to userdocs/diagnostic_groups/unknown-warning-group.md
diff --git a/userdocs/diagnostic_groups/Unsafe.md b/userdocs/diagnostic_groups/unsafe.md
similarity index 100%
rename from userdocs/diagnostic_groups/Unsafe.md
rename to userdocs/diagnostic_groups/unsafe.md