diff --git a/exports/taskfiles/utils/boost.yaml b/exports/taskfiles/utils/boost.yaml
index d286a3d..d6b1185 100644
--- a/exports/taskfiles/utils/boost.yaml
+++ b/exports/taskfiles/utils/boost.yaml
@@ -2,6 +2,7 @@ version: "3"
 
 includes:
   checksum: "checksum.yaml"
+  misc: "misc.yaml"
   remote: "remote.yaml"
 
 set: ["u", "pipefail"]
@@ -61,9 +62,8 @@ tasks:
   # @param {string} BUILD_DIR Directory in which to build boost.
   # @param {string} INSTALL_PREFIX Path prefix of where the project should be installed.
   # @param {string[]} [EXTRA_ARGS] Any additional arguments to pass to the build command.
-  # @param {int} [JOBS] The maximum number of concurrent processes to use when building. If
-  # omitted, the b2 default number is used. Before 1.76.0, the number was 1. Since 1.76.0, the
-  # default is the number of cores.
+  # @param {int} [JOBS={{default .G_NPROCS (env "TASK_EXTERNAL_TOOL_CONCURRENCY")}}] The maximum
+  # number of concurrent processes to use when building.
   # @param {string} [CMAKE_SETTINGS_DIR] If set, the directory where the project's CMake settings
   # file should be stored.
   build-and-install:
@@ -72,7 +72,7 @@ tasks:
       EXTRA_ARGS:
         ref: "default (list) .EXTRA_ARGS"
       JOBS: >-
-        {{default "" .JOBS}}
+        {{default (default .G_NPROCS (env "TASK_EXTERNAL_TOOL_CONCURRENCY")) .JOBS}}
     requires:
       vars: ["GENERATE_DIR", "BUILD_DIR", "INSTALL_PREFIX"]
     cmds:
@@ -121,9 +121,7 @@ tasks:
   #
   # Boost build-and-install parameters
   # @param {string} [BUILD_DIR={{.WORK_DIR}}/boost-build] Directory in which to build the project.
-  # @param {int} [JOBS] The maximum number of concurrent processes to use when building. If
-  # omitted, the b2 default number is used. Before 1.76.0, the number was 1. Since 1.76.0, the
-  # default is the number of cores.
+  # @param {int} [JOBS] The maximum number of concurrent processes to use when building.
   # @param {string[]} [BUILD_AND_INSTALL_ARGS] Any additional arguments to pass to boost's build
   # and install command.
   # @param {string} [CMAKE_SETTINGS_DIR] If set, the directory where the project's CMake settings
@@ -155,8 +153,6 @@ tasks:
         {{default (printf "%s/boost-build" .WORK_DIR) .BUILD_DIR}}
       BUILD_AND_INSTALL_ARGS:
         ref: "default (list) .BUILD_AND_INSTALL_ARGS"
-      JOBS: >-
-        {{default "" .JOBS}}
       CMAKE_SETTINGS_DIR: >-
         {{default "" .CMAKE_SETTINGS_DIR}}
     requires:
diff --git a/exports/taskfiles/utils/cmake.yaml b/exports/taskfiles/utils/cmake.yaml
index f14699c..39525cf 100644
--- a/exports/taskfiles/utils/cmake.yaml
+++ b/exports/taskfiles/utils/cmake.yaml
@@ -14,8 +14,8 @@ tasks:
   #
   # @param {string} BUILD_DIR Directory containing the generated build system to use.
   # @param {string[]} [EXTRA_ARGS] Any additional arguments to pass to the build command.
-  # @param {int} [JOBS] The maximum number of concurrent processes to use when building. If
-  # omitted, the native build tool's default number is used. See `man cmake`.
+  # @param {int} [JOBS={{default .G_NPROCS (env "TASK_EXTERNAL_TOOL_CONCURRENCY")}}] The maximum
+  # number of concurrent processes to use when building.
   # @param {string[]} [TARGETS] A list of specific targets to build instead of the default target.
   build:
     internal: true
@@ -24,7 +24,7 @@ tasks:
       EXTRA_ARGS:
         ref: "default (list) .EXTRA_ARGS"
       JOBS: >-
-        {{default "" .JOBS}}
+        {{default (default .G_NPROCS (env "TASK_EXTERNAL_TOOL_CONCURRENCY")) .JOBS}}
       TARGETS:
         ref: "default (list) .TARGETS"
     requires:
@@ -153,8 +153,7 @@ tasks:
   # command.
   # @param {string[]} [CMAKE_INSTALL_ARGS] Any additional arguments to pass to the CMake install
   # command.
-  # @param {int} [CMAKE_JOBS] The maximum number of concurrent processes to use when building. If
-  # omitted, the native build tool's default number is used. See `man cmake`.
+  # @param {int} [CMAKE_JOBS] The maximum number of concurrent processes to use when building.
   # @param {string} [CMAKE_SETTINGS_DIR] The directory where the project's CMake settings file
   # should be stored.
   # @param {string} [CMAKE_SOURCE_DIR=.] The path, within the extraction directory, containing the
@@ -172,8 +171,6 @@ tasks:
         ref: "default (list) .CMAKE_GEN_ARGS"
       CMAKE_INSTALL_ARGS:
         ref: "default (list) .CMAKE_INSTALL_ARGS"
-      CMAKE_JOBS: >-
-        {{default "" .CMAKE_JOBS}}
       CMAKE_SETTINGS_DIR: >-
         {{default "" .CMAKE_SETTINGS_DIR}}
       CMAKE_SOURCE_DIR: >-
diff --git a/exports/taskfiles/utils/misc.yaml b/exports/taskfiles/utils/misc.yaml
index 5bd3801..33c1999 100644
--- a/exports/taskfiles/utils/misc.yaml
+++ b/exports/taskfiles/utils/misc.yaml
@@ -3,6 +3,10 @@ version: "3"
 set: ["u", "pipefail"]
 shopt: ["globstar"]
 
+vars:
+  G_NPROCS:
+    sh: "getconf _NPROCESSORS_ONLN"
+
 tasks:
   replace-text:
     desc: "Replaces some text in a file using sed."