diff --git a/include/swift/AST/DiagnosticsFrontend.def b/include/swift/AST/DiagnosticsFrontend.def
index 7f52123bed721..dd5a18ab55e4d 100644
--- a/include/swift/AST/DiagnosticsFrontend.def
+++ b/include/swift/AST/DiagnosticsFrontend.def
@@ -80,6 +80,8 @@ ERROR(error_unknown_arg,none,
       "unknown argument: '%0'", (StringRef))
 ERROR(error_invalid_arg_value,none,
       "invalid value '%1' in '%0'", (StringRef, StringRef))
+ERROR(error_invalid_arg_combination,none,
+      "unsupported argument combination: '%0' and '%1'", (StringRef, StringRef))
 WARNING(warning_invalid_locale_code,none,
       "unsupported locale code; supported locale codes are: '%0'", (StringRef))
 WARNING(warning_locale_path_not_found,none,
diff --git a/include/swift/Option/FrontendOptions.td b/include/swift/Option/FrontendOptions.td
index 6c53cbc492fc0..93a277688027a 100644
--- a/include/swift/Option/FrontendOptions.td
+++ b/include/swift/Option/FrontendOptions.td
@@ -213,7 +213,8 @@ def dependency_scan_cache_remarks : Flag<["-"], "Rdependency-scan-cache">,
   HelpText<"Emit remarks indicating use of the serialized module dependency scanning cache.">;
 
 def enable_copy_propagation : Flag<["-"], "enable-copy-propagation">,
-  HelpText<"Run SIL copy propagation to shorten object lifetime.">;
+  HelpText<"Run SIL copy propagation with lexical lifetimes to shorten object "
+           "lifetimes while preserving variable lifetimes.">;
 def disable_copy_propagation : Flag<["-"], "disable-copy-propagation">,
   HelpText<"Don't run SIL copy propagation to preserve object lifetime.">;
 
@@ -259,15 +260,18 @@ def enable_experimental_concurrency :
   Flag<["-"], "enable-experimental-concurrency">,
   HelpText<"Enable experimental concurrency model">;
 
-def disable_lexical_lifetimes :
-  Flag<["-"], "disable-lexical-lifetimes">,
-  HelpText<"Disables early lexical lifetimes. Mutually exclusive with "
-           "-enable-lexical-lifetimes">;
-
+def enable_lexical_borrow_scopes :
+  Joined<["-"], "enable-lexical-borrow-scopes=">,
+  HelpText<"Whether to emit lexical borrow scopes (default: true)">,
+  MetaVarName<"true|false">;
+          
 def enable_lexical_lifetimes :
+  Joined<["-"], "enable-lexical-lifetimes=">,
+  HelpText<"Whether to enable lexical lifetimes">,
+  MetaVarName<"true|false">;
+def enable_lexical_lifetimes_noArg :
   Flag<["-"], "enable-lexical-lifetimes">,
-  HelpText<"Enable lexical lifetimes. Mutually exclusive with "
-           "-disable-lexical-lifetimes">;
+  HelpText<"Enable lexical lifetimes">;
 
 def enable_experimental_move_only :
   Flag<["-"], "enable-experimental-move-only">,
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index cc60ba016612a..c286e25230226 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -1449,21 +1449,88 @@ static bool ParseSILArgs(SILOptions &Opts, ArgList &Args,
   // -Ounchecked might also set removal of runtime asserts (cond_fail).
   Opts.RemoveRuntimeAsserts |= Args.hasArg(OPT_RemoveRuntimeAsserts);
 
-  // If experimental move only is enabled, always enable lexical lifetime as
-  // well. Move only depends on lexical lifetimes.
-  bool enableExperimentalLexicalLifetimes =
-      Args.hasArg(OPT_enable_lexical_lifetimes) ||
-      Args.hasArg(OPT_enable_experimental_move_only);
-  // Error if both experimental lexical lifetimes and disable lexical lifetimes
-  // are both set.
-  if (enableExperimentalLexicalLifetimes &&
-      Args.hasArg(OPT_disable_lexical_lifetimes)) {
+  Optional<bool> enableLexicalBorrowScopesFlag;
+  if (Arg *A = Args.getLastArg(OPT_enable_lexical_borrow_scopes)) {
+    enableLexicalBorrowScopesFlag =
+        llvm::StringSwitch<Optional<bool>>(A->getValue())
+            .Case("true", true)
+            .Case("false", false)
+            .Default(None);
+  }
+  Optional<bool> enableLexicalLifetimesFlag;
+  if (Arg *A = Args.getLastArg(OPT_enable_lexical_lifetimes)) {
+    enableLexicalLifetimesFlag =
+        llvm::StringSwitch<Optional<bool>>(A->getValue())
+            .Case("true", true)
+            .Case("false", false)
+            .Default(None);
+  }
+  if (Args.getLastArg(OPT_enable_lexical_lifetimes_noArg)) {
+    if (!enableLexicalLifetimesFlag.getValueOr(true)) {
+      // Error if lexical lifetimes have been disabled via the meta-var form
+      // and enabled via the flag.
+      Diags.diagnose(SourceLoc(), diag::error_invalid_arg_combination,
+                     "enable-lexical-lifetimes",
+                     "enable-lexical-lifetimes=false");
+      return true;
+    } else {
+      enableLexicalLifetimesFlag = true;
+    }
+  }
+
+  if (enableLexicalLifetimesFlag.getValueOr(false) &&
+      !enableLexicalBorrowScopesFlag.getValueOr(true)) {
+    // Error if lexical lifetimes have been enabled but lexical borrow scopes--
+    // on which they are dependent--have been disabled.
+    Diags.diagnose(SourceLoc(), diag::error_invalid_arg_combination,
+                   "enable-lexical-lifetimes=true",
+                   "enable-lexical-borrow-scopes=false");
     return true;
-  } else {
-    if (enableExperimentalLexicalLifetimes)
+  }
+
+  if (Args.hasArg(OPT_enable_experimental_move_only) &&
+      (enableLexicalBorrowScopesFlag.getValueOr(false))) {
+    // Error if move-only is enabled and lexical borrow scopes--on which it
+    // depends--has been disabled.
+    Diags.diagnose(SourceLoc(), diag::error_invalid_arg_combination,
+                   "enable-experimental-move-only",
+                   "enable-lexical-borrow-scopes=false");
+    return true;
+  }
+
+  if (Args.hasArg(OPT_enable_experimental_move_only) &&
+      (enableLexicalLifetimesFlag.getValueOr(false))) {
+    // Error if move-only is enabled and lexical lifetimes--on which it
+    // depends--has been disabled.
+    Diags.diagnose(SourceLoc(), diag::error_invalid_arg_combination,
+                   "enable-experimental-move-only",
+                   "enable-lexical-lifetimes=false");
+    return true;
+  }
+
+  // -enable-copy-propagation implies -enable-lexical-lifetimes unless
+  // otherwise specified.
+  if (Args.hasArg(OPT_enable_copy_propagation))
+    Opts.LexicalLifetimes = LexicalLifetimesOption::ExperimentalLate;
+
+  // If move-only is enabled, always enable lexical lifetime as well.  Move-only
+  // depends on lexical lifetimes.
+  if (Args.hasArg(OPT_enable_experimental_move_only))
+    Opts.LexicalLifetimes = LexicalLifetimesOption::ExperimentalLate;
+
+  if (enableLexicalLifetimesFlag) {
+    if (*enableLexicalLifetimesFlag) {
       Opts.LexicalLifetimes = LexicalLifetimesOption::ExperimentalLate;
-    if (Args.hasArg(OPT_disable_lexical_lifetimes))
+    } else {
+      Opts.LexicalLifetimes = LexicalLifetimesOption::Early;
+    }
+  }
+  if (enableLexicalBorrowScopesFlag) {
+    if (*enableLexicalBorrowScopesFlag) {
+      Opts.LexicalLifetimes = LexicalLifetimesOption::Early;
+    } else {
       Opts.LexicalLifetimes = LexicalLifetimesOption::Off;
+    }
   }
 
   Opts.EnableCopyPropagation |= Args.hasArg(OPT_enable_copy_propagation);
diff --git a/lib/SILOptimizer/Utils/CanonicalizeInstruction.cpp b/lib/SILOptimizer/Utils/CanonicalizeInstruction.cpp
index 22c9f87ff1843..c989263a8eb01 100644
--- a/lib/SILOptimizer/Utils/CanonicalizeInstruction.cpp
+++ b/lib/SILOptimizer/Utils/CanonicalizeInstruction.cpp
@@ -415,8 +415,8 @@ broadenSingleElementStores(StoreInst *storeInst,
 /// borrow scope--copy/destroy is insufficient by itself.
 ///
 /// FIXME: Technically this should be guarded by a compiler flag like
-/// -enable-copy-propagation until SILGen protects scoped variables by borrow
-/// scopes.
+/// -enable-copy-propagation until SILGen protects scoped variables by
+/// borrow scopes.
 static SILBasicBlock::iterator
 eliminateSimpleCopies(CopyValueInst *cvi, CanonicalizeInstruction &pass) {
   auto next = std::next(cvi->getIterator());
diff --git a/test/AutoDiff/validation-test/array.swift b/test/AutoDiff/validation-test/array.swift
index 7eb460631ec52..f84d6f315838a 100644
--- a/test/AutoDiff/validation-test/array.swift
+++ b/test/AutoDiff/validation-test/array.swift
@@ -1,4 +1,4 @@
-// RUN: %target-run-simple-swift(-Xfrontend -disable-lexical-lifetimes)
+// RUN: %target-run-simple-swift(-Xfrontend -enable-lexical-borrow-scopes=false)
 
 // REQUIRES: executable_test
 
diff --git a/test/AutoDiff/validation-test/optional.swift b/test/AutoDiff/validation-test/optional.swift
index 83b273f9cb8b0..4a10255867a76 100644
--- a/test/AutoDiff/validation-test/optional.swift
+++ b/test/AutoDiff/validation-test/optional.swift
@@ -1,4 +1,4 @@
-// RUN: %target-run-simple-swift(-Xfrontend -disable-lexical-lifetimes)
+// RUN: %target-run-simple-swift(-Xfrontend -enable-lexical-borrow-scopes=false)
 
 // REQUIRES: executable_test
 
diff --git a/test/AutoDiff/validation-test/optional_property.swift b/test/AutoDiff/validation-test/optional_property.swift
index 414145a2244ef..8bf5eafe3cdf5 100644
--- a/test/AutoDiff/validation-test/optional_property.swift
+++ b/test/AutoDiff/validation-test/optional_property.swift
@@ -1,5 +1,5 @@
-// RUN: %target-run-simple-swift(-Xfrontend -disable-lexical-lifetimes)
-// RUN: %target-swift-emit-sil -Xllvm -debug-only=differentiation -disable-lexical-lifetimes -module-name null -o /dev/null 2>&1 %s | %FileCheck %s
+// RUN: %target-run-simple-swift(-Xfrontend -enable-lexical-borrow-scopes=false)
+// RUN: %target-swift-emit-sil -Xllvm -debug-only=differentiation -enable-lexical-borrow-scopes=false -module-name null -o /dev/null 2>&1 %s | %FileCheck %s
 
 // REQUIRES: executable_test
 // REQUIRES: asserts
diff --git a/test/Concurrency/Runtime/async_properties_actor.swift b/test/Concurrency/Runtime/async_properties_actor.swift
index 0d2c5f0b02bba..06e0025a4eb07 100644
--- a/test/Concurrency/Runtime/async_properties_actor.swift
+++ b/test/Concurrency/Runtime/async_properties_actor.swift
@@ -1,4 +1,4 @@
-// RUN: %target-run-simple-swift(-parse-as-library -Xfrontend -enable-copy-propagation  -Xfrontend -disable-availability-checking %import-libdispatch) | %FileCheck %s
+// RUN: %target-run-simple-swift(-parse-as-library -Xfrontend -enable-copy-propagation -Xfrontend -enable-lexical-lifetimes=false  -Xfrontend -disable-availability-checking %import-libdispatch) | %FileCheck %s
 
 // REQUIRES: executable_test
 // REQUIRES: concurrency
diff --git a/test/DebugInfo/if-branchlocations.swift b/test/DebugInfo/if-branchlocations.swift
index 0cdd228727226..fa03eeb2f103a 100644
--- a/test/DebugInfo/if-branchlocations.swift
+++ b/test/DebugInfo/if-branchlocations.swift
@@ -1,5 +1,5 @@
 // RUN: %target-swift-frontend %s -emit-sil -disable-copy-propagation -emit-verbose-sil -g -o - | %FileCheck %s --check-prefixes=CHECK,CHECK-NCP
-// RUN: %target-swift-frontend %s -emit-sil -enable-copy-propagation -disable-lexical-lifetimes -emit-verbose-sil -g -o - | %FileCheck %s --check-prefixes=CHECK,CHECK-CP
+// RUN: %target-swift-frontend %s -emit-sil -enable-copy-propagation -enable-lexical-borrow-scopes=false -emit-verbose-sil -g -o - | %FileCheck %s --check-prefixes=CHECK,CHECK-CP
 
 class NSURL {}
 
diff --git a/test/DebugInfo/linetable-do.swift b/test/DebugInfo/linetable-do.swift
index 8b212dc3e1fab..576ae47afc6c9 100644
--- a/test/DebugInfo/linetable-do.swift
+++ b/test/DebugInfo/linetable-do.swift
@@ -1,6 +1,6 @@
 // RUN: %target-swift-frontend -Xllvm -sil-full-demangle %s -emit-ir -g -o - | %FileCheck %s
 // RUN: %target-swift-frontend -Xllvm -sil-full-demangle -disable-copy-propagation %s -emit-sil -emit-verbose-sil -g -o - | %FileCheck --check-prefixes=CHECK-SIL,CHECK-NCP %s
-// RUN: %target-swift-frontend -Xllvm -sil-full-demangle -enable-copy-propagation -disable-lexical-lifetimes %s -emit-sil -emit-verbose-sil -g -o - | %FileCheck --check-prefixes=CHECK-SIL,CHECK-CP %s
+// RUN: %target-swift-frontend -Xllvm -sil-full-demangle -enable-copy-propagation -enable-lexical-borrow-scopes=false %s -emit-sil -emit-verbose-sil -g -o - | %FileCheck --check-prefixes=CHECK-SIL,CHECK-CP %s
 import StdlibUnittest
 
 class Obj {}
diff --git a/test/IRGen/debug_poison.swift b/test/IRGen/debug_poison.swift
index e68044e964832..9359086c80a79 100644
--- a/test/IRGen/debug_poison.swift
+++ b/test/IRGen/debug_poison.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -primary-file %s -emit-ir -Onone -enable-copy-propagation -disable-lexical-lifetimes | %FileCheck %s -DINT=i%target-ptrsize
+// RUN: %target-swift-frontend -primary-file %s -emit-ir -Onone -enable-copy-propagation -enable-lexical-borrow-scopes=false | %FileCheck %s -DINT=i%target-ptrsize
 
 // Test debug_value [poison] emission
 
diff --git a/test/IRGen/unmanaged_objc_throw_func.swift b/test/IRGen/unmanaged_objc_throw_func.swift
index e79760212e9d7..8c619801c2e1d 100644
--- a/test/IRGen/unmanaged_objc_throw_func.swift
+++ b/test/IRGen/unmanaged_objc_throw_func.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -emit-ir -enable-copy-propagation %s | %FileCheck %s
+// RUN: %target-swift-frontend -emit-ir -enable-copy-propagation -enable-lexical-lifetimes=false %s | %FileCheck %s
 // REQUIRES: objc_interop
 // REQUIRES: optimized_stdlib
 
diff --git a/test/Interpreter/builtin_bridge_object.swift b/test/Interpreter/builtin_bridge_object.swift
index a391e63f11925..c6ee190825200 100644
--- a/test/Interpreter/builtin_bridge_object.swift
+++ b/test/Interpreter/builtin_bridge_object.swift
@@ -1,5 +1,5 @@
-// RUN: %target-run-simple-swift(-Onone -parse-stdlib -Xfrontend -enable-copy-propagation -Xfrontend -disable-lexical-lifetimes) | %FileCheck %s --check-prefixes=CHECK,CHECK-DBG
-// RUN: %target-run-simple-swift(-O -parse-stdlib -Xfrontend -enable-copy-propagation -Xfrontend -disable-lexical-lifetimes) | %FileCheck --check-prefixes=CHECK,CHECK-OPT %s
+// RUN: %target-run-simple-swift(-Onone -parse-stdlib -Xfrontend -enable-copy-propagation -Xfrontend -enable-lexical-borrow-scopes=false) | %FileCheck %s --check-prefixes=CHECK,CHECK-DBG
+// RUN: %target-run-simple-swift(-O -parse-stdlib -Xfrontend -enable-copy-propagation -Xfrontend -enable-lexical-borrow-scopes=false) | %FileCheck --check-prefixes=CHECK,CHECK-OPT %s
 
 // REQUIRES: executable_test
 // REQUIRES: objc_interop
diff --git a/test/SILOptimizer/OSLogFullOptTest.swift b/test/SILOptimizer/OSLogFullOptTest.swift
index bb858e916bf4b..79e1244ba6771 100644
--- a/test/SILOptimizer/OSLogFullOptTest.swift
+++ b/test/SILOptimizer/OSLogFullOptTest.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -emit-ir -swift-version 5 -O -enable-copy-propagation -primary-file %s | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%target-ptrsize
+// RUN: %target-swift-frontend -emit-ir -swift-version 5 -O -enable-copy-propagation -enable-lexical-lifetimes=false -primary-file %s | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%target-ptrsize
 //
 // REQUIRES: VENDOR=apple
 // REQUIRES: swift_stdlib_no_asserts
diff --git a/test/SILOptimizer/allocbox_to_stack.sil b/test/SILOptimizer/allocbox_to_stack.sil
index 5b7b752037832..c864889c982db 100644
--- a/test/SILOptimizer/allocbox_to_stack.sil
+++ b/test/SILOptimizer/allocbox_to_stack.sil
@@ -1,4 +1,4 @@
-// RUN: %target-sil-opt -sil-print-debuginfo -enable-sil-verify-all %s -allocbox-to-stack -disable-lexical-lifetimes | %FileCheck %s
+// RUN: %target-sil-opt -sil-print-debuginfo -enable-sil-verify-all %s -allocbox-to-stack -enable-lexical-borrow-scopes=false | %FileCheck %s
 
 sil_stage raw
 
diff --git a/test/SILOptimizer/allocbox_to_stack_ownership.sil b/test/SILOptimizer/allocbox_to_stack_ownership.sil
index 1650ebc8dab3a..8181671035c6f 100644
--- a/test/SILOptimizer/allocbox_to_stack_ownership.sil
+++ b/test/SILOptimizer/allocbox_to_stack_ownership.sil
@@ -1,4 +1,4 @@
-// RUN: %target-sil-opt -enable-sil-verify-all %s -allocbox-to-stack -disable-lexical-lifetimes | %FileCheck %s
+// RUN: %target-sil-opt -enable-sil-verify-all %s -allocbox-to-stack -enable-lexical-borrow-scopes=false | %FileCheck %s
 
 sil_stage raw
 
diff --git a/test/SILOptimizer/assemblyvision_remark/basic.swift b/test/SILOptimizer/assemblyvision_remark/basic.swift
index a4607ed80534e..5c13d5db17b3f 100644
--- a/test/SILOptimizer/assemblyvision_remark/basic.swift
+++ b/test/SILOptimizer/assemblyvision_remark/basic.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swiftc_driver -O -Rpass-missed=sil-assembly-vision-remark-gen -Xllvm -sil-disable-pass=FunctionSignatureOpts -Xfrontend -enable-copy-propagation -emit-sil %s -o /dev/null -Xfrontend -verify -Xfrontend -disable-lexical-lifetimes
+// RUN: %target-swiftc_driver -O -Rpass-missed=sil-assembly-vision-remark-gen -Xllvm -sil-disable-pass=FunctionSignatureOpts -Xfrontend -enable-copy-propagation -emit-sil %s -o /dev/null -Xfrontend -verify -Xfrontend -enable-lexical-borrow-scopes=false
 // REQUIRES: optimized_stdlib,swift_stdlib_no_asserts
 
 public class Klass {
diff --git a/test/SILOptimizer/assemblyvision_remark/basic_yaml.swift b/test/SILOptimizer/assemblyvision_remark/basic_yaml.swift
index a650b1946347f..6cac91306c699 100644
--- a/test/SILOptimizer/assemblyvision_remark/basic_yaml.swift
+++ b/test/SILOptimizer/assemblyvision_remark/basic_yaml.swift
@@ -1,7 +1,7 @@
-// RUN: %target-swiftc_driver -O -Rpass-missed=sil-assembly-vision-remark-gen -Xllvm -sil-disable-pass=FunctionSignatureOpts -Xfrontend -enable-copy-propagation -emit-sil %s -o /dev/null -Xfrontend -verify -Xfrontend -disable-lexical-lifetimes
+// RUN: %target-swiftc_driver -O -Rpass-missed=sil-assembly-vision-remark-gen -Xllvm -sil-disable-pass=FunctionSignatureOpts -Xfrontend -enable-copy-propagation -emit-sil %s -o /dev/null -Xfrontend -verify -Xfrontend -enable-lexical-borrow-scopes=false
 
 // RUN: %empty-directory(%t)
-// RUN: %target-swiftc_driver -wmo -O -Xllvm -sil-disable-pass=FunctionSignatureOpts -Xfrontend -enable-copy-propagation -emit-sil -save-optimization-record=yaml  -save-optimization-record-path %t/note.yaml -Xfrontend -disable-lexical-lifetimes %s -o /dev/null && %FileCheck --input-file=%t/note.yaml %s
+// RUN: %target-swiftc_driver -wmo -O -Xllvm -sil-disable-pass=FunctionSignatureOpts -Xfrontend -enable-copy-propagation -emit-sil -save-optimization-record=yaml  -save-optimization-record-path %t/note.yaml -Xfrontend -enable-lexical-borrow-scopes=false %s -o /dev/null && %FileCheck --input-file=%t/note.yaml %s
 
 // REQUIRES: optimized_stdlib,swift_stdlib_no_asserts
 
diff --git a/test/SILOptimizer/diagnose_lifetime_issues.swift b/test/SILOptimizer/diagnose_lifetime_issues.swift
index ebc4e1d90ccae..2b2fd9f38e62c 100644
--- a/test/SILOptimizer/diagnose_lifetime_issues.swift
+++ b/test/SILOptimizer/diagnose_lifetime_issues.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -emit-sil -disable-lexical-lifetimes -enable-copy-propagation %s -o /dev/null -verify
+// RUN: %target-swift-frontend -emit-sil -enable-lexical-borrow-scopes=false -enable-copy-propagation %s -o /dev/null -verify
 
 class Delegate {
   func foo() { }
diff --git a/test/SILOptimizer/diagnose_lifetime_issues_objc.swift b/test/SILOptimizer/diagnose_lifetime_issues_objc.swift
index 235af58ff7b10..87e2228f7e105 100644
--- a/test/SILOptimizer/diagnose_lifetime_issues_objc.swift
+++ b/test/SILOptimizer/diagnose_lifetime_issues_objc.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -emit-sil %s -disable-lexical-lifetimes -enable-copy-propagation -o /dev/null -verify
+// RUN: %target-swift-frontend -emit-sil %s -enable-lexical-borrow-scopes=false -enable-copy-propagation -o /dev/null -verify
 // REQUIRES: objc_interop
 
 import Foundation
diff --git a/test/SILOptimizer/opaque_values_mandatory.sil b/test/SILOptimizer/opaque_values_mandatory.sil
index baff8f69b52c0..91a998b4211e7 100644
--- a/test/SILOptimizer/opaque_values_mandatory.sil
+++ b/test/SILOptimizer/opaque_values_mandatory.sil
@@ -1,7 +1,8 @@
 // RUN: %target-sil-opt -diagnostics -enable-sil-opaque-values %s | \
 // RUN:     %target-sil-opt -Onone-performance -enable-sil-verify-all \
 // RUN:                     -enable-sil-opaque-values -emit-sorted-sil \
-// RUN:                     -enable-ossa-modules -enable-copy-propagation | \
+// RUN:                     -enable-ossa-modules -enable-copy-propagation \
+// RUN:                     -enable-lexical-borrow-scopes | \
 // RUN:     %FileCheck %s
 
 import Builtin
diff --git a/test/SILOptimizer/outliner.swift b/test/SILOptimizer/outliner.swift
index b16ee288679d7..68557cd64b8d6 100644
--- a/test/SILOptimizer/outliner.swift
+++ b/test/SILOptimizer/outliner.swift
@@ -1,5 +1,5 @@
-// RUN: %target-swift-frontend -Osize -import-objc-header %S/Inputs/Outliner.h %s -emit-sil -enforce-exclusivity=unchecked -enable-copy-propagation -disable-lexical-lifetimes | %FileCheck %s
-// RUN: %target-swift-frontend -Osize -g -import-objc-header %S/Inputs/Outliner.h %s -emit-sil -enforce-exclusivity=unchecked -enable-copy-propagation -disable-lexical-lifetimes | %FileCheck %s
+// RUN: %target-swift-frontend -Osize -import-objc-header %S/Inputs/Outliner.h %s -emit-sil -enforce-exclusivity=unchecked -enable-copy-propagation -enable-lexical-borrow-scopes=false | %FileCheck %s
+// RUN: %target-swift-frontend -Osize -g -import-objc-header %S/Inputs/Outliner.h %s -emit-sil -enforce-exclusivity=unchecked -enable-copy-propagation -enable-lexical-borrow-scopes=false | %FileCheck %s
 
 // REQUIRES: objc_interop
 // REQUIRES: optimized_stdlib
diff --git a/test/SILOptimizer/sil_combine_apply_ossa.sil b/test/SILOptimizer/sil_combine_apply_ossa.sil
index de18b09d757cc..e4dc98153dc13 100644
--- a/test/SILOptimizer/sil_combine_apply_ossa.sil
+++ b/test/SILOptimizer/sil_combine_apply_ossa.sil
@@ -1,4 +1,4 @@
-// RUN: %target-sil-opt -enable-ossa-modules -enable-copy-propagation -enable-sil-verify-all %s -sil-combine -sil-combine-disable-alloc-stack-opts | %FileCheck %s
+// RUN: %target-sil-opt -enable-ossa-modules -enable-copy-propagation -enable-lexical-lifetimes=false -enable-sil-verify-all %s -sil-combine -sil-combine-disable-alloc-stack-opts | %FileCheck %s
 
 import Swift
 import Builtin
diff --git a/test/SILOptimizer/sil_combine_ossa.sil b/test/SILOptimizer/sil_combine_ossa.sil
index 827c42db0267f..0a565e557645c 100644
--- a/test/SILOptimizer/sil_combine_ossa.sil
+++ b/test/SILOptimizer/sil_combine_ossa.sil
@@ -2,7 +2,7 @@
 // RUN: %target-sil-opt -enable-objc-interop -enforce-exclusivity=none -enable-sil-verify-all %s -sil-combine -generic-specializer | %FileCheck %s  --check-prefix=CHECK_FORWARDING_OWNERSHIP_KIND
 //
 // FIXME: check copy-propagation output instead once it is the default mode
-// RUN: %target-sil-opt -enable-objc-interop -enforce-exclusivity=none -enable-sil-verify-all %s -sil-combine -enable-copy-propagation | %FileCheck %s --check-prefix=CHECK_COPYPROP
+// RUN: %target-sil-opt -enable-objc-interop -enforce-exclusivity=none -enable-sil-verify-all %s -sil-combine -enable-copy-propagation -enable-lexical-lifetimes=false | %FileCheck %s --check-prefix=CHECK_COPYPROP
 
 // Declare this SIL to be canonical because some tests break raw SIL
 // conventions. e.g. address-type block args. -enforce-exclusivity=none is also
diff --git a/tools/sil-opt/SILOpt.cpp b/tools/sil-opt/SILOpt.cpp
index 226557fa780f7..d8f03256f5b5f 100644
--- a/tools/sil-opt/SILOpt.cpp
+++ b/tools/sil-opt/SILOpt.cpp
@@ -105,15 +105,16 @@ static llvm::cl::opt<bool>
 EnableExperimentalConcurrency("enable-experimental-concurrency",
                    llvm::cl::desc("Enable experimental concurrency model."));
 
-static llvm::cl::opt<bool> EnableExperimentalLexicalLifetimes(
-    "enable-lexical-lifetimes",
-    llvm::cl::desc("Enable experimental lexical lifetimes. Mutually exclusive "
-                   "with disable-lexical-lifetimes."));
+static llvm::cl::opt<bool> EnableLexicalLifetimes(
+    "enable-lexical-lifetimes", llvm::cl::init(false),
+    llvm::cl::desc("Enable lexical lifetimes. Mutually exclusive with "
+                   "enable-lexical-borrow-scopes and "
+                   "disable-lexical-lifetimes."));
 
-static llvm::cl::opt<bool> DisableLexicalLifetimes(
-    "disable-lexical-lifetimes",
-    llvm::cl::desc("Disable the default early lexical lifetimes. Mutually "
-                   "exclusive with enable-lexical-lifetimes"));
+static llvm::cl::opt<bool>
+    EnableLexicalBorrowScopes("enable-lexical-borrow-scopes",
+                              llvm::cl::init(true),
+                              llvm::cl::desc("Enable lexical borrow scopes."));
 
 static llvm::cl::opt<bool>
 EnableExperimentalMoveOnly("enable-experimental-move-only",
@@ -137,9 +138,9 @@ static llvm::cl::opt<bool> EnableOSSAModules(
                    "this is disabled we do not serialize in OSSA "
                    "form when optimizing."));
 
-static llvm::cl::opt<bool> EnableCopyPropagation(
-    "enable-copy-propagation",
-    llvm::cl::desc("Enable the copy propagation pass."));
+static llvm::cl::opt<bool>
+    EnableCopyPropagation("enable-copy-propagation",
+                          llvm::cl::desc("Enable the copy propagation pass."));
 
 static llvm::cl::opt<bool> DisableCopyPropagation(
     "disable-copy-propagation",
@@ -526,21 +527,22 @@ int main(int argc, char **argv) {
   SILOpts.EnableCopyPropagation = EnableCopyPropagation;
   SILOpts.DisableCopyPropagation = DisableCopyPropagation;
 
+  if (EnableCopyPropagation)
+    SILOpts.LexicalLifetimes = LexicalLifetimesOption::ExperimentalLate;
+
   // Enable lexical lifetimes if it is set or if experimental move only is
   // enabled. This is because move only depends on lexical lifetimes being
   // enabled and it saved some typing ; ).
-  bool enableExperimentalLexicalLifetimes =
-      EnableExperimentalLexicalLifetimes | EnableExperimentalMoveOnly;
-  if (enableExperimentalLexicalLifetimes && DisableLexicalLifetimes) {
-    fprintf(
-        stderr,
-        "Error! Can not specify both -enable-lexical-lifetimes "
-        "and -disable-lexical-lifetimes!\n");
+  bool enableLexicalLifetimes =
+      EnableLexicalLifetimes | EnableExperimentalMoveOnly;
+  if (enableLexicalLifetimes && !EnableLexicalBorrowScopes) {
+    fprintf(stderr, "Error! Cannot specify both -enable-lexical-lifetimes "
+                    "and either -enable-lexical-borrow-scopes=false");
     exit(-1);
   }
-  if (enableExperimentalLexicalLifetimes)
+  if (enableLexicalLifetimes)
     SILOpts.LexicalLifetimes = LexicalLifetimesOption::ExperimentalLate;
-  if (DisableLexicalLifetimes)
+  if (!EnableLexicalBorrowScopes)
     SILOpts.LexicalLifetimes = LexicalLifetimesOption::Off;
 
   serialization::ExtendedValidationInfo extendedInfo;
diff --git a/validation-test/SILOptimizer/lexical-lifetimes.swift b/validation-test/SILOptimizer/lexical-lifetimes.swift
index 1727970caeed1..8d66114471f98 100644
--- a/validation-test/SILOptimizer/lexical-lifetimes.swift
+++ b/validation-test/SILOptimizer/lexical-lifetimes.swift
@@ -1,4 +1,4 @@
-// RUN: %target-run-simple-swift(-Xfrontend -enable-lexical-lifetimes -Xfrontend -enable-copy-propagation) | %FileCheck %s
+// RUN: %target-run-simple-swift(-Xfrontend -enable-copy-propagation) | %FileCheck %s
 
 // REQUIRES: executable_test