diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -620,11 +620,11 @@
 
     std::string LinkerPath(GetProgramPath(LinkerName.c_str()));
     if (llvm::sys::fs::can_execute(LinkerPath)) {
-      // FIXME: Remove lld.darwinnew here once it's the only MachO lld.
+      // FIXME: Remove LinkerIsLLDDarwinNew once there's only one MachO lld.
       if (LinkerIsLLD)
-        *LinkerIsLLD = UseLinker == "lld" || UseLinker == "lld.darwinnew";
+        *LinkerIsLLD = UseLinker == "lld" || UseLinker == "lld.darwinold";
       if (LinkerIsLLDDarwinNew)
-        *LinkerIsLLDDarwinNew = UseLinker == "lld.darwinnew";
+        *LinkerIsLLDDarwinNew = UseLinker == "lld";
       return LinkerPath;
     }
   }
diff --git a/clang/test/Driver/Inputs/lld/ld64.lld.darwinnew b/clang/test/Driver/Inputs/lld/ld64.lld.darwinold
rename from clang/test/Driver/Inputs/lld/ld64.lld.darwinnew
rename to clang/test/Driver/Inputs/lld/ld64.lld.darwinold
diff --git a/clang/test/Driver/darwin-infer-simulator-sdkroot.c b/clang/test/Driver/darwin-infer-simulator-sdkroot.c
--- a/clang/test/Driver/darwin-infer-simulator-sdkroot.c
+++ b/clang/test/Driver/darwin-infer-simulator-sdkroot.c
@@ -4,9 +4,9 @@
 //
 // RUN: rm -rf %t/SDKs/iPhoneOS8.0.0.sdk
 // RUN: mkdir -p %t/SDKs/iPhoneOS8.0.0.sdk
-// RUN: env SDKROOT=%t/SDKs/iPhoneOS8.0.0.sdk %clang %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/iPhoneOS8.0.0.sdk %clang -fuse-ld= %s -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-IPHONE %s
-// RUN: env SDKROOT=%t/SDKs/iPhoneOS8.0.0.sdk IPHONEOS_DEPLOYMENT_TARGET=8.0 %clang %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/iPhoneOS8.0.0.sdk IPHONEOS_DEPLOYMENT_TARGET=8.0 %clang -fuse-ld= %s -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-IPHONE %s
 // CHECK-IPHONE: clang
 // CHECK-IPHONE: "-cc1"
@@ -17,7 +17,7 @@
 //
 // RUN: rm -rf %t/SDKs/iPhoneSimulator8.0.sdk
 // RUN: mkdir -p %t/SDKs/iPhoneSimulator8.0.sdk
-// RUN: env SDKROOT=%t/SDKs/iPhoneSimulator8.0.sdk %clang -arch x86_64 %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/iPhoneSimulator8.0.sdk %clang -fuse-ld= -arch x86_64 %s -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-SIMULATOR %s
 //
 // CHECK-SIMULATOR: clang
@@ -29,7 +29,7 @@
 //
 // RUN: rm -rf %t/SDKs/iPhoneSimulator14.0.sdk
 // RUN: mkdir -p %t/SDKs/iPhoneSimulator14.0.sdk
-// RUN: env SDKROOT=%t/SDKs/iPhoneSimulator14.0.sdk %clang -arch arm64 %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/iPhoneSimulator14.0.sdk %clang -fuse-ld= -arch arm64 %s -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-SIMULATOR-ARM64 %s
 //
 // CHECK-SIMULATOR-ARM64: clang
@@ -41,9 +41,9 @@
 //
 // RUN: rm -rf %t/SDKs/WatchOS3.0.sdk
 // RUN: mkdir -p %t/SDKs/WatchOS3.0.sdk
-// RUN: env SDKROOT=%t/SDKs/WatchOS3.0.sdk %clang %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/WatchOS3.0.sdk %clang %s -fuse-ld= -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-WATCH %s
-// RUN: env WATCHOS_DEPLOYMENT_TARGET=3.0 %clang %s -isysroot %t/SDKs/WatchOS3.0.sdk -mlinker-version=400 -### 2>&1 \
+// RUN: env WATCHOS_DEPLOYMENT_TARGET=3.0 %clang %s -fuse-ld= -isysroot %t/SDKs/WatchOS3.0.sdk -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-WATCH %s
 //
 // CHECK-WATCH: clang
@@ -55,7 +55,7 @@
 //
 // RUN: rm -rf %t/SDKs/WatchSimulator3.0.sdk
 // RUN: mkdir -p %t/SDKs/WatchSimulator3.0.sdk
-// RUN: env SDKROOT=%t/SDKs/WatchSimulator3.0.sdk %clang -arch x86_64 %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/WatchSimulator3.0.sdk %clang -fuse-ld= -arch x86_64 %s -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-WATCH-SIMULATOR %s
 //
 // CHECK-WATCH-SIMULATOR: clang
@@ -67,7 +67,7 @@
 //
 // RUN: rm -rf %t/SDKs/WatchSimulator7.0.sdk
 // RUN: mkdir -p %t/SDKs/WatchSimulator7.0.sdk
-// RUN: env SDKROOT=%t/SDKs/WatchSimulator7.0.sdk %clang -arch arm64 %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/WatchSimulator7.0.sdk %clang -fuse-ld= -arch arm64 %s -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-WATCH-SIMULATOR-ARM64 %s
 //
 // CHECK-WATCH-SIMULATOR-ARM64: clang
@@ -79,7 +79,7 @@
 //
 // RUN: rm -rf %t/SDKs/AppleTVOS10.0.sdk
 // RUN: mkdir -p %t/SDKs/AppleTVOS10.0.sdk
-// RUN: env SDKROOT=%t/SDKs/AppleTVOS10.0.sdk %clang %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/AppleTVOS10.0.sdk %clang %s -fuse-ld= -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-TV %s
 //
 // CHECK-TV: clang
@@ -91,7 +91,7 @@
 //
 // RUN: rm -rf %t/SDKs/AppleTVSimulator10.0.sdk
 // RUN: mkdir -p %t/SDKs/AppleTVSimulator10.0.sdk
-// RUN: env SDKROOT=%t/SDKs/AppleTVSimulator10.0.sdk %clang -arch x86_64 %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/AppleTVSimulator10.0.sdk %clang -fuse-ld= -arch x86_64 %s -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-TV-SIMULATOR %s
 //
 // CHECK-TV-SIMULATOR: clang
@@ -103,7 +103,7 @@
 //
 // RUN: rm -rf %t/SDKs/AppleTVSimulator14.0.sdk
 // RUN: mkdir -p %t/SDKs/AppleTVSimulator14.0.sdk
-// RUN: env SDKROOT=%t/SDKs/AppleTVSimulator14.0.sdk %clang -arch arm64 %s -mlinker-version=400 -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/AppleTVSimulator14.0.sdk %clang -fuse-ld= -arch arm64 %s -mlinker-version=400 -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-TV-SIMULATOR-ARM64 %s
 //
 // CHECK-TV-SIMULATOR-ARM64: clang
diff --git a/clang/test/Driver/darwin-ld-demangle-lld.c b/clang/test/Driver/darwin-ld-demangle-lld.c
--- a/clang/test/Driver/darwin-ld-demangle-lld.c
+++ b/clang/test/Driver/darwin-ld-demangle-lld.c
@@ -1,12 +1,13 @@
 // With -fuse-ld=lld, -demangle is always passed to the linker on Darwin.
 // REQUIRES: shell
 
+// FIXME: Remove this test case when we remove the lld.darwinold backend.
 // RUN: %clang --target=x86_64-apple-darwin -### \
-// RUN:   -fuse-ld=lld -B%S/Inputs/lld -mlinker-version=0 %s 2>&1 \
+// RUN:   -fuse-ld=lld.darwinold -B%S/Inputs/lld -mlinker-version=0 %s 2>&1 \
 // RUN:   | FileCheck %s
-// FIXME: Remove ld.darwinnew once it's the default (and only) mach-o lld.
+
 // RUN: %clang --target=x86_64-apple-darwin -### \
-// RUN:   -fuse-ld=lld.darwinnew -B%S/Inputs/lld -mlinker-version=0 %s 2>&1 \
+// RUN:   -fuse-ld=lld -B%S/Inputs/lld -mlinker-version=0 %s 2>&1 \
 // RUN:   | FileCheck %s
 
 // CHECK: "-demangle"
diff --git a/clang/test/Driver/darwin-ld-lto.c b/clang/test/Driver/darwin-ld-lto.c
--- a/clang/test/Driver/darwin-ld-lto.c
+++ b/clang/test/Driver/darwin-ld-lto.c
@@ -5,7 +5,7 @@
 // RUN: mkdir -p %t/bin
 // RUN: mkdir -p %t/lib
 // RUN: touch %t/lib/libLTO.dylib
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -fuse-ld= -target x86_64-apple-darwin10 -### %s \
 // RUN:   -ccc-install-dir %t/bin -mlinker-version=133 2> %t.log
 // RUN: FileCheck -check-prefix=LINK_LTOLIB_PATH %s -input-file %t.log
 //
@@ -14,7 +14,7 @@
 
 // Also pass -lto_library even if the file doesn't exist; if it's needed at
 // link time, ld will complain instead.
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -fuse-ld= -target x86_64-apple-darwin10 -### %s \
 // RUN:   -ccc-install-dir %S/dummytestdir -mlinker-version=133 2> %t.log
 // RUN: FileCheck -check-prefix=LINK_LTOLIB_PATH %s -input-file %t.log
 
diff --git a/clang/test/Driver/darwin-ld-platform-version-ios.c b/clang/test/Driver/darwin-ld-platform-version-ios.c
--- a/clang/test/Driver/darwin-ld-platform-version-ios.c
+++ b/clang/test/Driver/darwin-ld-platform-version-ios.c
@@ -1,6 +1,6 @@
 // RUN: touch %t.o
 
-// RUN: %clang -target arm64-apple-ios12.3 -fuse-ld= \
+// RUN: %clang -target arm64-apple-ios12.3 -fuse-ld=lld.darwinold \
 // RUN:   -isysroot %S/Inputs/iPhoneOS13.0.sdk -mlinker-version=0 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-OLD %s
@@ -12,7 +12,7 @@
 // RUN:   -isysroot %S/Inputs/iPhoneOS13.0.sdk -mlinker-version=520 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-NEW %s
-// RUN: %clang -target arm64-apple-ios12.3 -fuse-ld=lld.darwinnew \
+// RUN: %clang -target arm64-apple-ios12.3 -fuse-ld=lld \
 // RUN:   -isysroot %S/Inputs/iPhoneOS13.0.sdk -mlinker-version=0 \
 // RUN:   -### %t.o -B%S/Inputs/lld 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-NEW  %s
@@ -20,7 +20,7 @@
 // RUN:   -isysroot %S/Inputs/iPhoneOS13.0.sdk -mlinker-version=520 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=SIMUL %s
-// RUN: %clang -target x86_64-apple-ios13-simulator -fuse-ld=lld.darwinnew \
+// RUN: %clang -target x86_64-apple-ios13-simulator -fuse-ld=lld \
 // RUN:   -isysroot %S/Inputs/iPhoneOS13.0.sdk -mlinker-version=0 \
 // RUN:   -### %t.o -B%S/Inputs/lld 2>&1 \
 // RUN:   | FileCheck --check-prefix=SIMUL %s
diff --git a/clang/test/Driver/darwin-ld-platform-version-macos.c b/clang/test/Driver/darwin-ld-platform-version-macos.c
--- a/clang/test/Driver/darwin-ld-platform-version-macos.c
+++ b/clang/test/Driver/darwin-ld-platform-version-macos.c
@@ -1,10 +1,10 @@
 // RUN: touch %t.o
 
-// RUN: %clang -target x86_64-apple-macos10.13 -fuse-ld= \
+// RUN: %clang -target x86_64-apple-macos10.13 -fuse-ld=lld.darwinold \
 // RUN:   -isysroot %S/Inputs/MacOSX10.14.sdk -mlinker-version=0 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-OLD %s
-// RUN: %clang -target x86_64-apple-macos10.13 -fuse-ld=lld.darwinnew \
+// RUN: %clang -target x86_64-apple-macos10.13 -fuse-ld=lld \
 // RUN:   -isysroot %S/Inputs/MacOSX10.14.sdk -mlinker-version=0 \
 // RUN:   -### %t.o -B%S/Inputs/lld 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-NEW %s
@@ -21,7 +21,7 @@
 // RUN:   -isysroot %S/Inputs/MacOSX10.14.sdk -mlinker-version=400 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=ARM64_OLD %s
-// RUN: %clang -target arm64-apple-macos10.13 -fuse-ld=lld.darwinnew \
+// RUN: %clang -target arm64-apple-macos10.13 -fuse-ld=lld \
 // RUN:   -isysroot %S/Inputs/MacOSX10.14.sdk -mlinker-version=400 \
 // RUN:   -### %t.o -B%S/Inputs/lld 2>&1 \
 // RUN:   | FileCheck --check-prefix=ARM64_NEW %s
diff --git a/clang/test/Driver/darwin-ld-platform-version-tvos.c b/clang/test/Driver/darwin-ld-platform-version-tvos.c
--- a/clang/test/Driver/darwin-ld-platform-version-tvos.c
+++ b/clang/test/Driver/darwin-ld-platform-version-tvos.c
@@ -1,6 +1,6 @@
 // RUN: touch %t.o
 
-// RUN: %clang -target arm64-apple-tvos12.3 -fuse-ld= \
+// RUN: %clang -target arm64-apple-tvos12.3 -fuse-ld=lld.darwinold \
 // RUN:   -isysroot %S/Inputs/iPhoneOS13.0.sdk -mlinker-version=0 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-OLD %s
@@ -8,7 +8,7 @@
 // RUN:   -isysroot %S/Inputs/iPhoneOS13.0.sdk -mlinker-version=400 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-OLD %s
-// RUN: %clang -target arm64-apple-tvos12.3 -fuse-ld=lld.darwinnew \
+// RUN: %clang -target arm64-apple-tvos12.3 -fuse-ld=lld \
 // RUN:   -isysroot %S/Inputs/iPhoneOS13.0.sdk -mlinker-version=0 \
 // RUN:   -### %t.o -B%S/Inputs/lld 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-NEW %s
diff --git a/clang/test/Driver/darwin-ld-platform-version-watchos.c b/clang/test/Driver/darwin-ld-platform-version-watchos.c
--- a/clang/test/Driver/darwin-ld-platform-version-watchos.c
+++ b/clang/test/Driver/darwin-ld-platform-version-watchos.c
@@ -1,6 +1,6 @@
 // RUN: touch %t.o
 
-// RUN: %clang -target arm64_32-apple-watchos5.2 -fuse-ld= \
+// RUN: %clang -target arm64_32-apple-watchos5.2 -fuse-ld=lld.darwinold \
 // RUN:   -isysroot %S/Inputs/WatchOS6.0.sdk -mlinker-version=0 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-OLD %s
@@ -8,7 +8,7 @@
 // RUN:   -isysroot %S/Inputs/WatchOS6.0.sdk -mlinker-version=400 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-OLD %s
-// RUN: %clang -target arm64_32-apple-watchos5.2 -fuse-ld=lld.darwinnew \
+// RUN: %clang -target arm64_32-apple-watchos5.2 -fuse-ld=lld \
 // RUN:   -isysroot %S/Inputs/WatchOS6.0.sdk -mlinker-version=0 \
 // RUN:   -### %t.o -B%S/Inputs/lld 2>&1 \
 // RUN:   | FileCheck --check-prefix=LINKER-NEW %s
diff --git a/clang/test/Driver/darwin-sdkroot.c b/clang/test/Driver/darwin-sdkroot.c
--- a/clang/test/Driver/darwin-sdkroot.c
+++ b/clang/test/Driver/darwin-sdkroot.c
@@ -43,7 +43,7 @@
 //
 // RUN: rm -rf %t/SDKs/iPhoneOS8.0.0.sdk
 // RUN: mkdir -p %t/SDKs/iPhoneOS8.0.0.sdk
-// RUN: env SDKROOT=%t/SDKs/iPhoneOS8.0.0.sdk %clang -target arm64-apple-darwin -mlinker-version=400 --sysroot="" %s -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/iPhoneOS8.0.0.sdk %clang -fuse-ld= -target arm64-apple-darwin -mlinker-version=400 --sysroot="" %s -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-IPHONE %s
 //
 // CHECK-IPHONE: clang
@@ -55,7 +55,7 @@
 //
 // RUN: rm -rf %t/SDKs/iPhoneSimulator8.0.sdk
 // RUN: mkdir -p %t/SDKs/iPhoneSimulator8.0.sdk
-// RUN: env SDKROOT=%t/SDKs/iPhoneSimulator8.0.sdk %clang -target x86_64-apple-darwin -mlinker-version=400 --sysroot="" %s -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/iPhoneSimulator8.0.sdk %clang -fuse-ld= -target x86_64-apple-darwin -mlinker-version=400 --sysroot="" %s -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-SIMULATOR %s
 //
 // CHECK-SIMULATOR: clang
@@ -66,7 +66,7 @@
 //
 // RUN: rm -rf %t/SDKs/MacOSX10.10.0.sdk
 // RUN: mkdir -p %t/SDKs/MacOSX10.10.0.sdk
-// RUN: env SDKROOT=%t/SDKs/MacOSX10.10.0.sdk %clang -target x86_64-apple-darwin -mlinker-version=400 --sysroot="" %s -### 2>&1 \
+// RUN: env SDKROOT=%t/SDKs/MacOSX10.10.0.sdk %clang -fuse-ld= -target x86_64-apple-darwin -mlinker-version=400 --sysroot="" %s -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-MACOSX %s
 //
 // CHECK-MACOSX: clang
diff --git a/clang/test/Driver/target-triple-deployment.c b/clang/test/Driver/target-triple-deployment.c
--- a/clang/test/Driver/target-triple-deployment.c
+++ b/clang/test/Driver/target-triple-deployment.c
@@ -1,16 +1,16 @@
 // RUN: touch %t.o
-// RUN: %clang -target x86_64-apple-macosx10.4 -mlinker-version=400 -### %t.o 2> %t.log
-// RUN: %clang -target x86_64-apple-darwin9 -mlinker-version=400 -### %t.o 2>> %t.log
-// RUN: %clang -target x86_64-apple-macosx10.7 -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target x86_64-apple-macosx10.4 -mlinker-version=400 -### %t.o 2> %t.log
+// RUN: %clang -fuse-ld= -target x86_64-apple-darwin9 -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target x86_64-apple-macosx10.7 -mlinker-version=400 -### %t.o 2>> %t.log
 //
-// RUN: %clang -target armv7-apple-ios -mlinker-version=400 -### %t.o 2>> %t.log
-// RUN: %clang -target armv7-apple-ios0.0 -mlinker-version=400 -### %t.o 2>> %t.log
-// RUN: %clang -target armv7-apple-ios1.2.3 -mlinker-version=400 -### %t.o 2>> %t.log
-// RUN: %clang -target armv7-apple-ios5.0 -mlinker-version=400 -### %t.o 2>> %t.log
-// RUN: %clang -target armv7-apple-ios7.0 -mlinker-version=400 -### %t.o 2>> %t.log
-// RUN: %clang -target arm64-apple-ios -mlinker-version=400 -### %t.o 2>> %t.log
-// RUN: %clang -target arm64e-apple-ios13.0 -mlinker-version=400 -### %t.o 2>> %t.log
-// RUN: %clang -target arm64e-apple-ios14.1 -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target armv7-apple-ios -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target armv7-apple-ios0.0 -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target armv7-apple-ios1.2.3 -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target armv7-apple-ios5.0 -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target armv7-apple-ios7.0 -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target arm64-apple-ios -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target arm64e-apple-ios13.0 -mlinker-version=400 -### %t.o 2>> %t.log
+// RUN: %clang -fuse-ld= -target arm64e-apple-ios14.1 -mlinker-version=400 -### %t.o 2>> %t.log
 //
 // RUN: FileCheck %s < %t.log