diff --git a/Sources/XCTest/Private/WallClockTimeMetric.swift b/Sources/XCTest/Private/WallClockTimeMetric.swift
index 2fe945a346..64361647b1 100644
--- a/Sources/XCTest/Private/WallClockTimeMetric.swift
+++ b/Sources/XCTest/Private/WallClockTimeMetric.swift
@@ -30,7 +30,7 @@ internal final class WallClockTimeMetric: PerformanceMetric {
         measurements.append(stopTime-startTime)
     }
 
-    private let maxRelativeStandardDeviation = 10.0
+    private let maxRelativeStandardDeviation = ProcessInfo.processInfo.environment["XCTEST_MEASURE_MAX_STDDEV"].flatMap({ Double($0) }) ?? 10.0
     private let standardDeviationNegligibilityThreshold = 0.1
 
     func calculateResults() -> String {