diff --git a/icu4c/source/common/unicode/unistr.h b/icu4c/source/common/unicode/unistr.h
index a992bf073a..15948627ee 100644
--- a/icu4c/source/common/unicode/unistr.h
+++ b/icu4c/source/common/unicode/unistr.h
@@ -4162,9 +4162,12 @@ UnicodeString::getTerminatedBuffer() {
   } else {
     UChar *array = getArrayStart();
     int32_t len = length();
+#ifndef U_VALGRIND
     if(len < getCapacity() && array[len] == 0) {
       return array;
-    } else if(cloneArrayIfNeeded(len+1)) {
+    }
+#endif
+    if(cloneArrayIfNeeded(len+1)) {
       array = getArrayStart();
       array[len] = 0;
       return array;
diff --git a/icu4c/source/test/intltest/ustrtest.cpp b/icu4c/source/test/intltest/ustrtest.cpp
index 77da82737e..3934921627 100644
--- a/icu4c/source/test/intltest/ustrtest.cpp
+++ b/icu4c/source/test/intltest/ustrtest.cpp
@@ -1090,7 +1090,15 @@ UnicodeStringTest::TestMiscellaneous()
 
     test1.setTo(TRUE, u, -1);
     q=test1.getTerminatedBuffer();
-    if(q!=u || test1.length()!=4 || q[3]!=8 || q[4]!=0) {
+#ifndef U_VALGRIND
+    // The VALGRIND option always copies the buffer for getTerminatedBuffer(),
+    //    to avoid reading uninitialized memory when checking for the termination.
+    if(q!=u) {
+        errln("UnicodeString(u[-1]).getTerminatedBuffer() returns a bad buffer");
+    }
+#endif
+
+    if(test1.length()!=4 || q[3]!=8 || q[4]!=0) {
         errln("UnicodeString(u[-1]).getTerminatedBuffer() returns a bad buffer");
     }