diff --git a/Makefile.inc1 b/Makefile.inc1
index 8f140a6ff6d..6a93be9aa8f 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -122,7 +122,7 @@ _CPUTYPE!=	MAKEFLAGS= CPUTYPE=${_TARGET_CPUTYPE} ${MAKE} \
 .error CPUTYPE global should be set with ?=.
 .endif
 .if make(buildworld)
-BUILD_ARCH!=	sysctl -n hw.machine_arch
+BUILD_ARCH!=	uname -m
 .if ${MACHINE_ARCH} != ${BUILD_ARCH}
 .error To cross-build, set TARGET_ARCH.
 .endif
diff --git a/lib/libc/gen/__xuname.c b/lib/libc/gen/__xuname.c
index 4d1be8c04f1..c7965743675 100644
--- a/lib/libc/gen/__xuname.c
+++ b/lib/libc/gen/__xuname.c
@@ -71,6 +71,8 @@ __xuname(int namesize, void *namebuf)
 			rval = -1;
 	}
 	name->sysname[sizeof(name->sysname) - 1] = '\0';
+	if ((p = getenv("UNAME_s")))
+		strncpy(name->sysname, p, sizeof(name->sysname));
 
 	mib[0] = CTL_KERN;
 	mib[1] = KERN_HOSTNAME;
@@ -95,6 +97,8 @@ __xuname(int namesize, void *namebuf)
 			rval = -1;
 	}
 	name->release[sizeof(name->release) - 1] = '\0';
+	if ((p = getenv("UNAME_r")))
+		strncpy(name->release, p, sizeof(name->release));
 
 	/* The version may have newlines in it, turn them into spaces. */
 	mib[0] = CTL_KERN;
@@ -116,6 +120,8 @@ __xuname(int namesize, void *namebuf)
 				*p = '\0';
 		}
 	}
+	if ((p = getenv("UNAME_v")))
+		strncpy(name->version, p, sizeof(name->version));
 
 	mib[0] = CTL_HW;
 	mib[1] = HW_MACHINE;
@@ -128,5 +134,7 @@ __xuname(int namesize, void *namebuf)
 			rval = -1;
 	}
 	name->machine[sizeof(name->machine) - 1] = '\0';
+	if ((p = getenv("UNAME_m")))
+		strncpy(name->machine, p, sizeof(name->machine));
 	return (rval);
 }
diff --git a/lib/libc/gen/getosreldate.c b/lib/libc/gen/getosreldate.c
index 22c400d1c73..03a00c1b6a8 100644
--- a/lib/libc/gen/getosreldate.c
+++ b/lib/libc/gen/getosreldate.c
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/sysctl.h>
+#include <stdlib.h>
 
 #include <osreldate.h>
 
@@ -49,10 +50,14 @@ getosreldate(void)
 	size_t size;
 	int value;
 
+	char *temp;
+
 	mib[0] = CTL_KERN;
 	mib[1] = KERN_OSRELDATE;
 	size = sizeof value;
 	if (sysctl(mib, 2, &value, &size, NULL, 0) == -1)
 		return (-1);
+	if ((temp = getenv("OSVERSION")))
+		value = atoi(temp);
 	return (value);
 }