diff --git a/infra/README.recipes.md b/infra/README.recipes.md
index c99a1bd..6fa4190 100644
--- a/infra/README.recipes.md
+++ b/infra/README.recipes.md
@@ -93,7 +93,7 @@
 
 Recipe for building GN.
 
-&mdash; **def [RunSteps](/infra/recipes/gn.py#30)(api, repository):**
+&mdash; **def [RunSteps](/infra/recipes/gn.py#101)(api, repository):**
 ### *recipes* / [macos\_sdk:examples/full](/infra/recipe_modules/macos_sdk/examples/full.py)
 
 [DEPS](/infra/recipe_modules/macos_sdk/examples/full.py#5): [macos\_sdk](#recipe_modules-macos_sdk), [recipe\_engine/platform][recipe_engine/recipe_modules/platform], [recipe\_engine/properties][recipe_engine/recipe_modules/properties], [recipe\_engine/step][recipe_engine/recipe_modules/step]
diff --git a/infra/recipes/gn.expected/ci_linux.json b/infra/recipes/gn.expected/ci_linux.json
index 4a301f2..54e55c4 100644
--- a/infra/recipes/gn.expected/ci_linux.json
+++ b/infra/recipes/gn.expected/ci_linux.json
@@ -96,6 +96,213 @@
   },
   {
     "cmd": [],
+    "name": "rpmalloc"
+  },
+  {
+    "cmd": [
+      "git",
+      "init",
+      "[START_DIR]/rpmalloc"
+    ],
+    "name": "rpmalloc.init",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
+      "fetch",
+      "--tags",
+      "https://fuchsia.googlesource.com/third_party/github.com/mjansson/rpmalloc",
+      "6bb6ca97a8d6a72d626153fd8431ef8477a21145"
+    ],
+    "cwd": "[START_DIR]/rpmalloc",
+    "infra_step": true,
+    "name": "rpmalloc.fetch",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
+      "checkout",
+      "FETCH_HEAD"
+    ],
+    "cwd": "[START_DIR]/rpmalloc",
+    "infra_step": true,
+    "name": "rpmalloc.checkout",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "rmtree",
+      "[CLEANUP]/rpmalloc-linux-amd64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.remove sources linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "copytree",
+      "[START_DIR]/rpmalloc",
+      "[CLEANUP]/rpmalloc-linux-amd64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.copy sources linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "name": "rpmalloc.build rpmalloc-linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "[CLEANUP]/rpmalloc-linux-amd64/configure.py",
+      "-c",
+      "release",
+      "-a",
+      "x86-64",
+      "--lto"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-amd64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-amd64.configure",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "[START_DIR]/cipd/ninja",
+      "lib/linux/release/x86-64/librpmallocwrap.a"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-amd64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-amd64.ninja",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "rmtree",
+      "[CLEANUP]/rpmalloc-linux-arm64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.remove sources linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "copytree",
+      "[START_DIR]/rpmalloc",
+      "[CLEANUP]/rpmalloc-linux-arm64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.copy sources linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "name": "rpmalloc.build rpmalloc-linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "[CLEANUP]/rpmalloc-linux-arm64/configure.py",
+      "-c",
+      "release",
+      "-a",
+      "arm64",
+      "--lto"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-arm64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-arm64.configure",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "[START_DIR]/cipd/ninja",
+      "lib/linux/release/arm64/librpmallocwrap.a"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-arm64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-arm64.ninja",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [],
     "name": "debug"
   },
   {
@@ -148,6 +355,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "debug.linux-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -170,7 +385,8 @@
       "-u",
       "[START_DIR]/gn/build/gen.py",
       "--use-lto",
-      "--use-icf"
+      "--use-icf",
+      "--link-lib=[CLEANUP]/rpmalloc-linux-amd64/lib/linux/release/x86-64/librpmallocwrap.a"
     ],
     "cwd": "[START_DIR]/gn",
     "env": {
@@ -208,6 +424,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -233,6 +457,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.upload.build gn/gn/linux-amd64",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
@@ -258,7 +490,8 @@
       "-u",
       "[START_DIR]/gn/build/gen.py",
       "--use-lto",
-      "--use-icf"
+      "--use-icf",
+      "--link-lib=[CLEANUP]/rpmalloc-linux-arm64/lib/linux/release/arm64/librpmallocwrap.a"
     ],
     "cwd": "[START_DIR]/gn",
     "env": {
@@ -312,6 +545,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-arm64.upload.build gn/gn/linux-arm64",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
diff --git a/infra/recipes/gn.expected/ci_mac.json b/infra/recipes/gn.expected/ci_mac.json
index fa8164d..5816d9c 100644
--- a/infra/recipes/gn.expected/ci_mac.json
+++ b/infra/recipes/gn.expected/ci_mac.json
@@ -144,21 +144,14 @@
     "name": "debug"
   },
   {
-    "cmd": [],
-    "name": "debug.mac-amd64",
-    "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@1@@@"
-    ]
-  },
-  {
     "cmd": [
       "xcrun",
       "--show-sdk-path"
     ],
-    "name": "debug.mac-amd64.xcrun sdk-path",
+    "name": "debug.xcrun sdk-path",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[sdk-path]@/some/xcode/path@@@",
       "@@@STEP_LOG_END@raw_io.output[sdk-path]@@@"
     ]
@@ -174,15 +167,22 @@
       "-Wp,-v",
       "-"
     ],
-    "name": "debug.mac-amd64.xcrun toolchain",
+    "name": "debug.xcrun toolchain",
     "stderr": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[toolchain]@[CACHE]/macos_sdk/XCode.app/include/c++/v1@@@",
       "@@@STEP_LOG_END@raw_io.output[toolchain]@@@"
     ]
   },
   {
+    "cmd": [],
+    "name": "debug.mac-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
     "cmd": [
       "python",
       "-u",
@@ -225,6 +225,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path -nostdinc++ -cxx-isystem [CACHE]/macos_sdk/XCode.app/include/c++/v1",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path"
+    },
     "name": "debug.mac-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -235,21 +243,14 @@
     "name": "release"
   },
   {
-    "cmd": [],
-    "name": "release.mac-amd64",
-    "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@1@@@"
-    ]
-  },
-  {
     "cmd": [
       "xcrun",
       "--show-sdk-path"
     ],
-    "name": "release.mac-amd64.xcrun sdk-path",
+    "name": "release.xcrun sdk-path",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[sdk-path]@/some/xcode/path@@@",
       "@@@STEP_LOG_END@raw_io.output[sdk-path]@@@"
     ]
@@ -265,15 +266,22 @@
       "-Wp,-v",
       "-"
     ],
-    "name": "release.mac-amd64.xcrun toolchain",
+    "name": "release.xcrun toolchain",
     "stderr": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[toolchain]@[CACHE]/macos_sdk/XCode.app/include/c++/v1@@@",
       "@@@STEP_LOG_END@raw_io.output[toolchain]@@@"
     ]
   },
   {
+    "cmd": [],
+    "name": "release.mac-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
     "cmd": [
       "python",
       "-u",
@@ -317,6 +325,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path -nostdinc++ -cxx-isystem [CACHE]/macos_sdk/XCode.app/include/c++/v1",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path"
+    },
     "name": "release.mac-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -342,6 +358,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path -nostdinc++ -cxx-isystem [CACHE]/macos_sdk/XCode.app/include/c++/v1",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path"
+    },
     "name": "release.mac-amd64.upload.build gn/gn/mac-amd64",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
@@ -355,21 +379,14 @@
     ]
   },
   {
-    "cmd": [],
-    "name": "release.mac-arm64",
-    "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@1@@@"
-    ]
-  },
-  {
     "cmd": [
       "xcrun",
       "--show-sdk-path"
     ],
-    "name": "release.mac-arm64.xcrun sdk-path",
+    "name": "release.xcrun sdk-path (2)",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[sdk-path]@/some/xcode/path@@@",
       "@@@STEP_LOG_END@raw_io.output[sdk-path]@@@"
     ]
@@ -385,15 +402,22 @@
       "-Wp,-v",
       "-"
     ],
-    "name": "release.mac-arm64.xcrun toolchain",
+    "name": "release.xcrun toolchain (2)",
     "stderr": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[toolchain]@[CACHE]/macos_sdk/XCode.app/include/c++/v1@@@",
       "@@@STEP_LOG_END@raw_io.output[toolchain]@@@"
     ]
   },
   {
+    "cmd": [],
+    "name": "release.mac-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
     "cmd": [
       "python",
       "-u",
@@ -453,6 +477,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=arm64-apple-darwin --sysroot=/some/xcode/path -nostdinc++ -cxx-isystem [CACHE]/macos_sdk/XCode.app/include/c++/v1",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=arm64-apple-darwin --sysroot=/some/xcode/path"
+    },
     "name": "release.mac-arm64.upload.build gn/gn/mac-arm64",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
diff --git a/infra/recipes/gn.expected/ci_win.json b/infra/recipes/gn.expected/ci_win.json
index 88e8edb..842f015 100644
--- a/infra/recipes/gn.expected/ci_win.json
+++ b/infra/recipes/gn.expected/ci_win.json
@@ -199,6 +199,7 @@
     "cmd": [
       "[START_DIR]\\gn\\out\\gn_unittests"
     ],
+    "cwd": "[START_DIR]\\gn",
     "env": {
       "VSINSTALLDIR": "[CACHE]\\windows_sdk"
     },
@@ -269,6 +270,7 @@
     "cmd": [
       "[START_DIR]\\gn\\out\\gn_unittests"
     ],
+    "cwd": "[START_DIR]\\gn",
     "env": {
       "VSINSTALLDIR": "[CACHE]\\windows_sdk"
     },
@@ -302,6 +304,7 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]\\gn",
     "env": {
       "VSINSTALLDIR": "[CACHE]\\windows_sdk"
     },
diff --git a/infra/recipes/gn.expected/cipd_exists.json b/infra/recipes/gn.expected/cipd_exists.json
index d7127c2..b93e7c4 100644
--- a/infra/recipes/gn.expected/cipd_exists.json
+++ b/infra/recipes/gn.expected/cipd_exists.json
@@ -96,6 +96,213 @@
   },
   {
     "cmd": [],
+    "name": "rpmalloc"
+  },
+  {
+    "cmd": [
+      "git",
+      "init",
+      "[START_DIR]/rpmalloc"
+    ],
+    "name": "rpmalloc.init",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
+      "fetch",
+      "--tags",
+      "https://fuchsia.googlesource.com/third_party/github.com/mjansson/rpmalloc",
+      "6bb6ca97a8d6a72d626153fd8431ef8477a21145"
+    ],
+    "cwd": "[START_DIR]/rpmalloc",
+    "infra_step": true,
+    "name": "rpmalloc.fetch",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
+      "checkout",
+      "FETCH_HEAD"
+    ],
+    "cwd": "[START_DIR]/rpmalloc",
+    "infra_step": true,
+    "name": "rpmalloc.checkout",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "rmtree",
+      "[CLEANUP]/rpmalloc-linux-amd64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.remove sources linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "copytree",
+      "[START_DIR]/rpmalloc",
+      "[CLEANUP]/rpmalloc-linux-amd64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.copy sources linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "name": "rpmalloc.build rpmalloc-linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "[CLEANUP]/rpmalloc-linux-amd64/configure.py",
+      "-c",
+      "release",
+      "-a",
+      "x86-64",
+      "--lto"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-amd64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-amd64.configure",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "[START_DIR]/cipd/ninja",
+      "lib/linux/release/x86-64/librpmallocwrap.a"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-amd64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-amd64.ninja",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "rmtree",
+      "[CLEANUP]/rpmalloc-linux-arm64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.remove sources linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "copytree",
+      "[START_DIR]/rpmalloc",
+      "[CLEANUP]/rpmalloc-linux-arm64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.copy sources linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "name": "rpmalloc.build rpmalloc-linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "[CLEANUP]/rpmalloc-linux-arm64/configure.py",
+      "-c",
+      "release",
+      "-a",
+      "arm64",
+      "--lto"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-arm64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-arm64.configure",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "[START_DIR]/cipd/ninja",
+      "lib/linux/release/arm64/librpmallocwrap.a"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-arm64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-arm64.ninja",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [],
     "name": "debug"
   },
   {
@@ -148,6 +355,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "debug.linux-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -170,7 +385,8 @@
       "-u",
       "[START_DIR]/gn/build/gen.py",
       "--use-lto",
-      "--use-icf"
+      "--use-icf",
+      "--link-lib=[CLEANUP]/rpmalloc-linux-amd64/lib/linux/release/x86-64/librpmallocwrap.a"
     ],
     "cwd": "[START_DIR]/gn",
     "env": {
@@ -208,6 +424,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -233,6 +457,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.upload.build gn/gn/linux-amd64",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
@@ -255,6 +487,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.upload.cipd search gn/gn/linux-amd64 git_revision:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
@@ -289,7 +529,8 @@
       "-u",
       "[START_DIR]/gn/build/gen.py",
       "--use-lto",
-      "--use-icf"
+      "--use-icf",
+      "--link-lib=[CLEANUP]/rpmalloc-linux-arm64/lib/linux/release/arm64/librpmallocwrap.a"
     ],
     "cwd": "[START_DIR]/gn",
     "env": {
@@ -343,6 +584,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-arm64.upload.build gn/gn/linux-arm64",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
@@ -365,6 +614,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-arm64.upload.cipd search gn/gn/linux-arm64 git_revision:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
diff --git a/infra/recipes/gn.expected/cipd_register.json b/infra/recipes/gn.expected/cipd_register.json
index 2e09f95..75d38d2 100644
--- a/infra/recipes/gn.expected/cipd_register.json
+++ b/infra/recipes/gn.expected/cipd_register.json
@@ -96,6 +96,213 @@
   },
   {
     "cmd": [],
+    "name": "rpmalloc"
+  },
+  {
+    "cmd": [
+      "git",
+      "init",
+      "[START_DIR]/rpmalloc"
+    ],
+    "name": "rpmalloc.init",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
+      "fetch",
+      "--tags",
+      "https://fuchsia.googlesource.com/third_party/github.com/mjansson/rpmalloc",
+      "6bb6ca97a8d6a72d626153fd8431ef8477a21145"
+    ],
+    "cwd": "[START_DIR]/rpmalloc",
+    "infra_step": true,
+    "name": "rpmalloc.fetch",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
+      "checkout",
+      "FETCH_HEAD"
+    ],
+    "cwd": "[START_DIR]/rpmalloc",
+    "infra_step": true,
+    "name": "rpmalloc.checkout",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "rmtree",
+      "[CLEANUP]/rpmalloc-linux-amd64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.remove sources linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "copytree",
+      "[START_DIR]/rpmalloc",
+      "[CLEANUP]/rpmalloc-linux-amd64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.copy sources linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "name": "rpmalloc.build rpmalloc-linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "[CLEANUP]/rpmalloc-linux-amd64/configure.py",
+      "-c",
+      "release",
+      "-a",
+      "x86-64",
+      "--lto"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-amd64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-amd64.configure",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "[START_DIR]/cipd/ninja",
+      "lib/linux/release/x86-64/librpmallocwrap.a"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-amd64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-amd64.ninja",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "rmtree",
+      "[CLEANUP]/rpmalloc-linux-arm64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.remove sources linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "copytree",
+      "[START_DIR]/rpmalloc",
+      "[CLEANUP]/rpmalloc-linux-arm64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.copy sources linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "name": "rpmalloc.build rpmalloc-linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "[CLEANUP]/rpmalloc-linux-arm64/configure.py",
+      "-c",
+      "release",
+      "-a",
+      "arm64",
+      "--lto"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-arm64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-arm64.configure",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "[START_DIR]/cipd/ninja",
+      "lib/linux/release/arm64/librpmallocwrap.a"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-arm64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-arm64.ninja",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [],
     "name": "debug"
   },
   {
@@ -148,6 +355,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "debug.linux-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -170,7 +385,8 @@
       "-u",
       "[START_DIR]/gn/build/gen.py",
       "--use-lto",
-      "--use-icf"
+      "--use-icf",
+      "--link-lib=[CLEANUP]/rpmalloc-linux-amd64/lib/linux/release/x86-64/librpmallocwrap.a"
     ],
     "cwd": "[START_DIR]/gn",
     "env": {
@@ -208,6 +424,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -233,6 +457,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.upload.build gn/gn/linux-amd64",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
@@ -255,6 +487,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.upload.cipd search gn/gn/linux-amd64 git_revision:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
@@ -278,6 +518,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.upload.register gn/gn/linux-amd64",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
@@ -303,7 +551,8 @@
       "-u",
       "[START_DIR]/gn/build/gen.py",
       "--use-lto",
-      "--use-icf"
+      "--use-icf",
+      "--link-lib=[CLEANUP]/rpmalloc-linux-arm64/lib/linux/release/arm64/librpmallocwrap.a"
     ],
     "cwd": "[START_DIR]/gn",
     "env": {
@@ -357,6 +606,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-arm64.upload.build gn/gn/linux-arm64",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
@@ -379,6 +636,14 @@
       "-json-output",
       "/path/to/tmp/json"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-arm64.upload.cipd search gn/gn/linux-arm64 git_revision:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@3@@@",
diff --git a/infra/recipes/gn.expected/cq_linux.json b/infra/recipes/gn.expected/cq_linux.json
index 75b64a4..2593ed3 100644
--- a/infra/recipes/gn.expected/cq_linux.json
+++ b/infra/recipes/gn.expected/cq_linux.json
@@ -123,6 +123,213 @@
   },
   {
     "cmd": [],
+    "name": "rpmalloc"
+  },
+  {
+    "cmd": [
+      "git",
+      "init",
+      "[START_DIR]/rpmalloc"
+    ],
+    "name": "rpmalloc.init",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
+      "fetch",
+      "--tags",
+      "https://fuchsia.googlesource.com/third_party/github.com/mjansson/rpmalloc",
+      "6bb6ca97a8d6a72d626153fd8431ef8477a21145"
+    ],
+    "cwd": "[START_DIR]/rpmalloc",
+    "infra_step": true,
+    "name": "rpmalloc.fetch",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
+      "checkout",
+      "FETCH_HEAD"
+    ],
+    "cwd": "[START_DIR]/rpmalloc",
+    "infra_step": true,
+    "name": "rpmalloc.checkout",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "rmtree",
+      "[CLEANUP]/rpmalloc-linux-amd64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.remove sources linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "copytree",
+      "[START_DIR]/rpmalloc",
+      "[CLEANUP]/rpmalloc-linux-amd64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.copy sources linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "name": "rpmalloc.build rpmalloc-linux-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "[CLEANUP]/rpmalloc-linux-amd64/configure.py",
+      "-c",
+      "release",
+      "-a",
+      "x86-64",
+      "--lto"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-amd64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-amd64.configure",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "[START_DIR]/cipd/ninja",
+      "lib/linux/release/x86-64/librpmallocwrap.a"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-amd64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-amd64.ninja",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "rmtree",
+      "[CLEANUP]/rpmalloc-linux-arm64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.remove sources linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[recipe_engine::file]/resources/fileutil.py",
+      "--json-output",
+      "/path/to/tmp/json",
+      "copytree",
+      "[START_DIR]/rpmalloc",
+      "[CLEANUP]/rpmalloc-linux-arm64"
+    ],
+    "infra_step": true,
+    "name": "rpmalloc.copy sources linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [],
+    "name": "rpmalloc.build rpmalloc-linux-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "[CLEANUP]/rpmalloc-linux-arm64/configure.py",
+      "-c",
+      "release",
+      "-a",
+      "arm64",
+      "--lto"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-arm64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-arm64.configure",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "[START_DIR]/cipd/ninja",
+      "lib/linux/release/arm64/librpmallocwrap.a"
+    ],
+    "cwd": "[CLEANUP]/rpmalloc-linux-arm64",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=aarch64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
+    "name": "rpmalloc.build rpmalloc-linux-arm64.ninja",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@2@@@"
+    ]
+  },
+  {
+    "cmd": [],
     "name": "debug"
   },
   {
@@ -175,6 +382,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "debug.linux-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -197,7 +412,8 @@
       "-u",
       "[START_DIR]/gn/build/gen.py",
       "--use-lto",
-      "--use-icf"
+      "--use-icf",
+      "--link-lib=[CLEANUP]/rpmalloc-linux-amd64/lib/linux/release/x86-64/librpmallocwrap.a"
     ],
     "cwd": "[START_DIR]/gn",
     "env": {
@@ -235,6 +451,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-linux-gnu --sysroot=[START_DIR]/cipd/sysroot -static-libstdc++"
+    },
     "name": "release.linux-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -253,7 +477,8 @@
       "-u",
       "[START_DIR]/gn/build/gen.py",
       "--use-lto",
-      "--use-icf"
+      "--use-icf",
+      "--link-lib=[CLEANUP]/rpmalloc-linux-arm64/lib/linux/release/arm64/librpmallocwrap.a"
     ],
     "cwd": "[START_DIR]/gn",
     "env": {
diff --git a/infra/recipes/gn.expected/cq_mac.json b/infra/recipes/gn.expected/cq_mac.json
index c1d51f5..3965438 100644
--- a/infra/recipes/gn.expected/cq_mac.json
+++ b/infra/recipes/gn.expected/cq_mac.json
@@ -171,21 +171,14 @@
     "name": "debug"
   },
   {
-    "cmd": [],
-    "name": "debug.mac-amd64",
-    "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@1@@@"
-    ]
-  },
-  {
     "cmd": [
       "xcrun",
       "--show-sdk-path"
     ],
-    "name": "debug.mac-amd64.xcrun sdk-path",
+    "name": "debug.xcrun sdk-path",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[sdk-path]@/some/xcode/path@@@",
       "@@@STEP_LOG_END@raw_io.output[sdk-path]@@@"
     ]
@@ -201,15 +194,22 @@
       "-Wp,-v",
       "-"
     ],
-    "name": "debug.mac-amd64.xcrun toolchain",
+    "name": "debug.xcrun toolchain",
     "stderr": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[toolchain]@[CACHE]/macos_sdk/XCode.app/include/c++/v1@@@",
       "@@@STEP_LOG_END@raw_io.output[toolchain]@@@"
     ]
   },
   {
+    "cmd": [],
+    "name": "debug.mac-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
     "cmd": [
       "python",
       "-u",
@@ -252,6 +252,14 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path -nostdinc++ -cxx-isystem [CACHE]/macos_sdk/XCode.app/include/c++/v1",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path"
+    },
     "name": "debug.mac-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
@@ -262,21 +270,14 @@
     "name": "release"
   },
   {
-    "cmd": [],
-    "name": "release.mac-amd64",
-    "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@1@@@"
-    ]
-  },
-  {
     "cmd": [
       "xcrun",
       "--show-sdk-path"
     ],
-    "name": "release.mac-amd64.xcrun sdk-path",
+    "name": "release.xcrun sdk-path",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[sdk-path]@/some/xcode/path@@@",
       "@@@STEP_LOG_END@raw_io.output[sdk-path]@@@"
     ]
@@ -292,15 +293,22 @@
       "-Wp,-v",
       "-"
     ],
-    "name": "release.mac-amd64.xcrun toolchain",
+    "name": "release.xcrun toolchain",
     "stderr": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[toolchain]@[CACHE]/macos_sdk/XCode.app/include/c++/v1@@@",
       "@@@STEP_LOG_END@raw_io.output[toolchain]@@@"
     ]
   },
   {
+    "cmd": [],
+    "name": "release.mac-amd64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
     "cmd": [
       "python",
       "-u",
@@ -344,27 +352,28 @@
     "cmd": [
       "[START_DIR]/gn/out/gn_unittests"
     ],
+    "cwd": "[START_DIR]/gn",
+    "env": {
+      "AR": "[START_DIR]/cipd/bin/llvm-ar",
+      "CC": "[START_DIR]/cipd/bin/clang",
+      "CFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path -nostdinc++ -cxx-isystem [CACHE]/macos_sdk/XCode.app/include/c++/v1",
+      "CXX": "[START_DIR]/cipd/bin/clang++",
+      "LDFLAGS": "--target=x86_64-apple-darwin --sysroot=/some/xcode/path"
+    },
     "name": "release.mac-amd64.test",
     "~followup_annotations": [
       "@@@STEP_NEST_LEVEL@2@@@"
     ]
   },
   {
-    "cmd": [],
-    "name": "release.mac-arm64",
-    "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@1@@@"
-    ]
-  },
-  {
     "cmd": [
       "xcrun",
       "--show-sdk-path"
     ],
-    "name": "release.mac-arm64.xcrun sdk-path",
+    "name": "release.xcrun sdk-path (2)",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[sdk-path]@/some/xcode/path@@@",
       "@@@STEP_LOG_END@raw_io.output[sdk-path]@@@"
     ]
@@ -380,15 +389,22 @@
       "-Wp,-v",
       "-"
     ],
-    "name": "release.mac-arm64.xcrun toolchain",
+    "name": "release.xcrun toolchain (2)",
     "stderr": "/path/to/tmp/",
     "~followup_annotations": [
-      "@@@STEP_NEST_LEVEL@2@@@",
+      "@@@STEP_NEST_LEVEL@1@@@",
       "@@@STEP_LOG_LINE@raw_io.output[toolchain]@[CACHE]/macos_sdk/XCode.app/include/c++/v1@@@",
       "@@@STEP_LOG_END@raw_io.output[toolchain]@@@"
     ]
   },
   {
+    "cmd": [],
+    "name": "release.mac-arm64",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@"
+    ]
+  },
+  {
     "cmd": [
       "python",
       "-u",
diff --git a/infra/recipes/gn.expected/cq_win.json b/infra/recipes/gn.expected/cq_win.json
index 164b245..7e4424b 100644
--- a/infra/recipes/gn.expected/cq_win.json
+++ b/infra/recipes/gn.expected/cq_win.json
@@ -226,6 +226,7 @@
     "cmd": [
       "[START_DIR]\\gn\\out\\gn_unittests"
     ],
+    "cwd": "[START_DIR]\\gn",
     "env": {
       "VSINSTALLDIR": "[CACHE]\\windows_sdk"
     },
@@ -296,6 +297,7 @@
     "cmd": [
       "[START_DIR]\\gn\\out\\gn_unittests"
     ],
+    "cwd": "[START_DIR]\\gn",
     "env": {
       "VSINSTALLDIR": "[CACHE]\\windows_sdk"
     },
diff --git a/infra/recipes/gn.py b/infra/recipes/gn.py
index 5c767b1..bac3233 100644
--- a/infra/recipes/gn.py
+++ b/infra/recipes/gn.py
@@ -26,10 +26,84 @@
     'repository': Property(kind=str, default='https://gn.googlesource.com/gn'),
 }
 
+# On select platforms, link the GN executable against rpmalloc for a small 10% speed boost.
+RPMALLOC_GIT_URL = 'https://fuchsia.googlesource.com/third_party/github.com/mjansson/rpmalloc'
+RPMALLOC_REVISION = '6bb6ca97a8d6a72d626153fd8431ef8477a21145'
+
+# Used to convert os and arch strings to rpmalloc format
+RPMALLOC_MAP = {
+    'amd64': 'x86-64',
+    'mac': 'macos',
+}
+
+
+def _get_libcxx_include_path(api):
+  # Run the preprocessor with an empty input and print all include paths.
+  lines = api.step(
+      'xcrun toolchain', [
+          'xcrun', '--toolchain', 'clang', 'clang++', '-xc++', '-fsyntax-only',
+          '-Wp,-v', '-'
+      ],
+      stderr=api.raw_io.output(name='toolchain', add_output_log=True),
+      step_test_data=lambda: api.raw_io.test_api.stream_output(
+          str(api.macos_sdk.sdk_dir.join('include', 'c++', 'v1')),
+          stream='stderr')).stderr.splitlines()
+  # Iterate over all include paths and look for the SDK libc++ one.
+  sdk_dir = str(api.macos_sdk.sdk_dir)
+  for line in lines:
+    line = line.strip()
+    if line.startswith(sdk_dir) and 'include/c++/v1' in line:
+      return line
+  return None  # pragma: no cover
+
+
+def _get_compilation_environment(api, target, cipd_dir):
+  if target.is_linux:
+    triple = '--target=%s' % target.triple
+    sysroot = '--sysroot=%s' % cipd_dir.join('sysroot')
+    env = {
+        'CC': cipd_dir.join('bin', 'clang'),
+        'CXX': cipd_dir.join('bin', 'clang++'),
+        'AR': cipd_dir.join('bin', 'llvm-ar'),
+        'CFLAGS': '%s %s' % (triple, sysroot),
+        'LDFLAGS': '%s %s -static-libstdc++' % (triple, sysroot),
+    }
+  elif target.is_mac:
+    triple = '--target=%s' % target.triple
+    sysroot = '--sysroot=%s' % api.step(
+        'xcrun sdk-path', ['xcrun', '--show-sdk-path'],
+        stdout=api.raw_io.output(name='sdk-path', add_output_log=True),
+        step_test_data=lambda: api.raw_io.test_api.stream_output(
+            '/some/xcode/path')).stdout.strip()
+    stdlib = cipd_dir.join('lib', 'libc++.a')
+    cxx_include = _get_libcxx_include_path(api)
+    env = {
+        'CC':
+            cipd_dir.join('bin', 'clang'),
+        'CXX':
+            cipd_dir.join('bin', 'clang++'),
+        'AR':
+            cipd_dir.join('bin', 'llvm-ar'),
+        'CFLAGS':
+            '%s %s -nostdinc++ -cxx-isystem %s' %
+            (triple, sysroot, cxx_include),
+        # TODO(phosek): Use the system libc++ temporarily until we
+        # have universal libc++.a for macOS that supports both x86_64
+        # and arm64.
+        'LDFLAGS':
+            '%s %s' % (triple, sysroot),
+    }
+  else:
+    env = {}
+
+  return env
+
 
 def RunSteps(api, repository):
   src_dir = api.path['start_dir'].join('gn')
 
+  # TODO: Verify that building and linking rpmalloc works on OS X and Windows as
+  # well.
   with api.step.nest('git'), api.context(infra_steps=True):
     api.step('init', ['git', 'init', src_dir])
 
@@ -84,85 +158,98 @@
           'name': 'release',
           'args': ['--use-lto', '--use-icf'],
           'targets': release_targets(),
+          # TODO: Enable this for OS X and Windows.
+          'use_rpmalloc': api.platform.is_linux
       },
   ]
 
-  def get_libcxx_include_path():
-    # Run the preprocessor with an empty input and print all include paths.
-    lines = api.step(
-        'xcrun toolchain', [
-            'xcrun', '--toolchain', 'clang', 'clang++', '-xc++',
-            '-fsyntax-only', '-Wp,-v', '-'
-        ],
-        stderr=api.raw_io.output(name='toolchain', add_output_log=True),
-        step_test_data=lambda: api.raw_io.test_api.stream_output(
-            str(api.macos_sdk.sdk_dir.join('include', 'c++', 'v1')),
-            stream='stderr')).stderr.splitlines()
-    # Iterate over all include paths and look for the SDK libc++ one.
-    sdk_dir = str(api.macos_sdk.sdk_dir)
-    for line in lines:
-      line = line.strip()
-      if line.startswith(sdk_dir) and 'include/c++/v1' in line:
-        return line
-    return None  # pragma: no cover
+  # True if any config uses rpmalloc.
+  use_rpmalloc = any(c.get('use_rpmalloc', False) for c in configs)
 
   with api.macos_sdk(), api.windows_sdk():
+    # Build the rpmalloc static libraries if needed.
+    if use_rpmalloc:
+      # Maps a target.platform string to the location of the corresponding
+      # rpmalloc static library.
+      rpmalloc_static_libs = {}
+
+      # Get the list of all target platforms that are listed in `configs`
+      # above. Note that this is a list of Target instances, some of them
+      # may refer to the same platform string (e.g. linux-amd64).
+      #
+      # For each platform, a version of rpmalloc will be built if necessary,
+      # but doing this properly requires having a valid target instance to
+      # call _get_compilation_environment. So create a { platform -> Target }
+      # map to do that later.
+      all_config_platforms = {}
+      for c in configs:
+        if not c.get('use_rpmalloc', False):
+          continue
+        for t in c['targets']:
+          if t.platform not in all_config_platforms:
+            all_config_platforms[t.platform] = t
+
+      rpmalloc_src_dir = api.path['start_dir'].join('rpmalloc')
+      with api.step.nest('rpmalloc'):
+        api.step('init', ['git', 'init', rpmalloc_src_dir])
+        with api.context(cwd=rpmalloc_src_dir, infra_steps=True):
+          api.step(
+              'fetch',
+              ['git', 'fetch', '--tags', RPMALLOC_GIT_URL, RPMALLOC_REVISION])
+          api.step('checkout', ['git', 'checkout', 'FETCH_HEAD'])
+
+        for platform in all_config_platforms:
+          # Convert target architecture and os to rpmalloc format.
+          rpmalloc_os, rpmalloc_arch = platform.split('-')
+          rpmalloc_os = RPMALLOC_MAP.get(rpmalloc_os, rpmalloc_os)
+          rpmalloc_arch = RPMALLOC_MAP.get(rpmalloc_arch, rpmalloc_arch)
+
+          # The rpmalloc build system doesn't support out-of-tree builds, and
+          # trying to build binaries for multiple target architectures doesn't
+          # work unless one cleans the build. To work around these issues,
+          # simply copy the source tree into a new clean directory.
+          rpmalloc_build_dir = api.path['cleanup'].join('rpmalloc-' + platform)
+          api.file.rmtree('remove sources ' + platform, rpmalloc_build_dir)
+          api.file.copytree('copy sources ' + platform, rpmalloc_src_dir,
+                            rpmalloc_build_dir)
+
+          env = _get_compilation_environment(api,
+                                             all_config_platforms[platform],
+                                             cipd_dir)
+          with api.step.nest('build rpmalloc-' + platform), api.context(
+              env=env, cwd=rpmalloc_build_dir):
+            api.python(
+                'configure',
+                rpmalloc_build_dir.join('configure.py'),
+                args=['-c', 'release', '-a', rpmalloc_arch, '--lto'])
+
+            # NOTE: Only build the static library.
+            rpmalloc_static_lib = api.path.join('lib', rpmalloc_os, 'release',
+                                                rpmalloc_arch,
+                                                'librpmallocwrap.a')
+            api.step('ninja', [cipd_dir.join('ninja'), rpmalloc_static_lib])
+
+          rpmalloc_static_libs[platform] = rpmalloc_build_dir.join(
+              rpmalloc_static_lib)
+
     for config in configs:
       with api.step.nest(config['name']):
         for target in config['targets']:
-          with api.step.nest(target.platform):
-            if target.is_linux:
-              triple = '--target=%s' % target.triple
-              sysroot = '--sysroot=%s' % cipd_dir.join('sysroot')
-              env = {
-                  'CC': cipd_dir.join('bin', 'clang'),
-                  'CXX': cipd_dir.join('bin', 'clang++'),
-                  'AR': cipd_dir.join('bin', 'llvm-ar'),
-                  'CFLAGS': '%s %s' % (triple, sysroot),
-                  'LDFLAGS': '%s %s -static-libstdc++' % (triple, sysroot),
-              }
-            elif target.is_mac:
-              triple = '--target=%s' % target.triple
-              sysroot = '--sysroot=%s' % api.step(
-                  'xcrun sdk-path', ['xcrun', '--show-sdk-path'],
-                  stdout=api.raw_io.output(
-                      name='sdk-path', add_output_log=True),
-                  step_test_data=lambda: api.raw_io.test_api.stream_output(
-                      '/some/xcode/path')).stdout.strip()
-              stdlib = cipd_dir.join('lib', 'libc++.a')
-              cxx_include = get_libcxx_include_path()
-              assert cxx_include, 'cannot find C++ header directory'
-              env = {
-                  'CC':
-                      cipd_dir.join('bin', 'clang'),
-                  'CXX':
-                      cipd_dir.join('bin', 'clang++'),
-                  'AR':
-                      cipd_dir.join('bin', 'llvm-ar'),
-                  # TODO(phosek): temporarily use XCode C++ headers to make
-                  # sure these are compatible with the system libc++.
-                  'CFLAGS':
-                      '%s %s -nostdinc++ -cxx-isystem %s' %
-                      (triple, sysroot, cxx_include),
-                  # TODO(phosek): Use the system libc++ temporarily until we
-                  # have universal libc++.a for macOS that supports both x86_64
-                  # and arm64.
-                  'LDFLAGS':
-                      '%s %s' % (triple, sysroot),
-              }
-            else:
-              env = {}
+          env = _get_compilation_environment(api, target, cipd_dir)
+          with api.step.nest(target.platform), api.context(
+              env=env, cwd=src_dir):
+            args = config['args']
+            if config.get('use_rpmalloc', False):
+              args = args[:] + [
+                  '--link-lib=%s' % rpmalloc_static_libs[target.platform]
+              ]
 
-            with api.context(env=env, cwd=src_dir):
-              api.python(
-                  'generate',
-                  src_dir.join('build', 'gen.py'),
-                  args=config['args'])
+            api.python('generate', src_dir.join('build', 'gen.py'), args=args)
 
-              # Windows requires the environment modifications when building too.
-              api.step('build',
-                       [cipd_dir.join('ninja'), '-C',
-                        src_dir.join('out')])
+            # Windows requires the environment modifications when building too.
+            api.step('build',
+                     [cipd_dir.join('ninja'), '-C',
+                      src_dir.join('out')])
 
             if target.is_host:
               api.step('test', [src_dir.join('out', 'gn_unittests')])