diff --git a/icu4c/source/common/uprops.c b/icu4c/source/common/uprops.c
index 23de6053322..a50744f1e81 100644
--- a/icu4c/source/common/uprops.c
+++ b/icu4c/source/common/uprops.c
@@ -258,6 +258,14 @@ u_isUWhiteSpace(UChar32 c) {
     return u_hasBinaryProperty(c, UCHAR_WHITE_SPACE);
 }
 
+U_CAPI UBool U_EXPORT2
+uprv_isRuleWhiteSpace(UChar32 c) {
+    /* "white space" in the sense of ICU rule parsers: Cf+White_Space */
+    return
+        u_charType(c)==U_FORMAT_CHAR ||
+        u_hasBinaryProperty(c, UCHAR_WHITE_SPACE);
+}
+
 U_CAPI int32_t U_EXPORT2
 u_getIntPropertyValue(UChar32 c, UProperty which) {
     UErrorCode errorCode;
diff --git a/icu4c/source/common/uprops.h b/icu4c/source/common/uprops.h
index 120a7e03104..bb0ae40adb6 100644
--- a/icu4c/source/common/uprops.h
+++ b/icu4c/source/common/uprops.h
@@ -230,4 +230,11 @@ uprv_comparePropertyNames(const char *name1, const char *name2);
 #define _Pi     FLAG(U_INITIAL_PUNCTUATION)
 #define _Pf     FLAG(U_FINAL_PUNCTUATION)
 
+/**
+ * Is this character a "white space" in the sense of ICU rule parsers?
+ * @internal
+ */
+U_CAPI UBool U_EXPORT2
+uprv_isRuleWhiteSpace(UChar32 c);
+
 #endif
diff --git a/icu4c/source/common/upropset.cpp b/icu4c/source/common/upropset.cpp
index 3fba281bb64..81e27bccd32 100644
--- a/icu4c/source/common/upropset.cpp
+++ b/icu4c/source/common/upropset.cpp
@@ -427,6 +427,20 @@ UnicodeSet* UnicodePropertySet::createBinaryPropertySet(const UnicodeString& nam
     return set;
 }
 
+UnicodeSet
+UnicodePropertySet::getRuleWhiteSpaceSet() {
+    UnicodeSet set;
+    int32_t code;
+
+    /* "white space" in the sense of ICU rule parsers: Cf+White_Space */
+    code = UCHAR_WHITE_SPACE;
+    initSetFromFilter(set, _binaryPropertyFilter, &code);
+
+    set.addAll(getCategorySet(U_FORMAT_CHAR));
+
+    return set; /* return by value */
+}
+
 //----------------------------------------------------------------
 // Utility methods
 //----------------------------------------------------------------
diff --git a/icu4c/source/common/upropset.h b/icu4c/source/common/upropset.h
index a82fd6fb374..e654d5d3a44 100644
--- a/icu4c/source/common/upropset.h
+++ b/icu4c/source/common/upropset.h
@@ -97,6 +97,12 @@ class UnicodePropertySet /* not : public UObject because all methods are static
 
     typedef UnicodeSet* (*SetFactory)(const UnicodeString& valueName);
 
+    /**
+     * "white space" in the sense of ICU rule parsers
+     * @internal
+     */
+    static UnicodeSet getRuleWhiteSpaceSet();
+
  private:
 
     //----------------------------------------------------------------